auto repair

Table of Contents

1. Auto Mechanic

2. Automobile

3. Art Car

4. Art Bike

5. Car Modding

6. Cut Down

7. Engine Tuning

8. Transmission

9. Suspension of a Vehicle

10. Different Types of Suspension

11. Dashpot

12. RLC Circuit

13. Shock Absorber

14. Multi-Link Suspension

15. Car Handling

16. Steering

17. Mechanical Engineering

18. Vehicle Dynamics

19. Some Important Guidelines for your Vehicle

Auto mechanic

A mechanic working on the rear end of a car.

An auto mechanic is a mechanic who specializes in automobile maintenance, repair, and sometimes modification and design. Education is usually post-secondary or secondary vocational education, although apprenticeship under a master mechanic is also an accepted method of learning the trade. A good mechanic must be proficient in mathematics, physics, electronics and computer science as well as logical processes used for diagnosing problems. Most reputable mechanics are ASE certified, which is a standardized method of testing skill level. The technology used in automobiles changes very rapidly and the mechanic must be prepared to learn these new technologies and systems. The auto mechanic has a physically demanding job, often exposed to temperature extremes and well as lifting heavy objects and staying in uncomfortable positions for extended periods as well as exposure to gasoline, solvents and other toxic chemicals. Related jobs include motorcycle repair and small engine repair.

Auto 'mechanics' are today professionally referred to as 'technicians', due to the level of technological competency now required to diagnose and perform needed repairs. Fading quickly is the day of the 'shadetree mechanic', who needed little knowledge of today's computerized systems. Today's technician must have knowledge of these systems, as well as more basic mechanical principles.

Due to the increasingly labyrinthine nature of the technology that is now incorporated into automobiles, most automobile dealerships now provide sophisticated diagnostic computers to each technician, without which they would be unable to diagnose or repair a multitude of common failures.

Mechanic

Mechanic at steam pump in electric power house

A mechanic is a person who uses tools to repair things (generally machinery) or works to keep things operating properly.

Many mechanics are specialised in a particular field such as auto mechanics, boiler mechanics, industrial maintenance mechanics (millwrights), air conditioning and refrigeration mechanics and aircraft mechanics.

Mechanics possess many skills in technical, electrical/electronic and other vocational areas. Being a good repair technician is more than just "fixing things". A good sound repair requires troubleshooting skills which at times requires the tech to teach themselves how a particuar system operates; often in a timely manner.

Automobile

Karl Benz's "Velo" model (1894) - entered into the first automobile race

An automobile is a wheeled passenger vehicle that carries its own motor. Most definitions of the term specify that automobiles are designed to run primarily on roads, to have seating for one to six people, typically have four wheels and be constructed principally for the transport of people rather than goods. However, the term is far from precise.

As of 2002 there were 590 million passenger cars worldwide (roughly one car for every eleven people), of which 140 million in the U.S. (roughly one car for every two people). .

History

An automobile powered by the Otto gasoline engine was invented in Germany by Karl Benz in 1885. Benz was granted a patent dated 29 January 1886 in Mannheim for that automobile. Even though Benz is credited with the invention of the modern automobile, several other German engineers worked on building automobiles at the same time. In 1886, Gottlieb Daimler and Wilhelm Maybach in Stuttgart patented the first motor bike, built and tested in 1885, and in 1886 they built a converted horse-drawn stagecoach. In 1870, German-Austrian inventor Siegfried Marcus assembled a motorized handcart, though Marcus' vehicle did not go beyond the experimental stage.

Automobile history eras

1890s 1900s 1910s 1920s 1930s 1940s 1950s 1960s1970s

1980s 1990s

2000s

Veteran Brass or Edwardian Vintage Pre-War

Antique

Post-War

Classic

Modern

Internal combustion engine powered vehicles

Animation of a 4-stroke overhead-cam internal combustion engine

In 1806 François Isaac de Rivaz, a Swiss, designed the first internal combustion engine (sometimes abbreviated "ICE" today). He subsequently used it to develop the world's first vehicle to run on such an engine that used a mixture of hydrogen and oxygen to generate energy. The design was not very successful, as was the case with the British inventor, Samuel Brown, and the American inventor, Samuel Morey, who produced vehicles powered by clumsy internal combustion engines about 1826.

Etienne Lenoir produced the first successful stationary internal combustion engine in 1860, and within a few years, about four hundred were in operation in Paris. About 1863, Lenoir installed his engine in a vehicle. It seems to have been powered by city lighting-gas in bottles, and was said by Lenoir to have "travelled more slowly than a man could walk, with breakdowns being frequent." Lenoir, in his patent of 1860, included the

provision of a carburettor, so liquid fuel could be substituted for gas, particularly for mobile purposes in vehicles. Lenoir is said to have tested liquid fuel, such as alcohol, in his stationary engines; but it does not appear that he used them in his own vehicle. If he did, he most certainly did not use gasoline, as this was not well-known and was considered a waste product.

The next innovation occurred in the late 1860s, with Siegfried Marcus, a German working in Vienna, Austria. He developed the idea of using gasoline as a fuel in a two-stroke internal combustion engine. In 1870, using a simple handcart, he built a crude vehicle with no seats, steering, or brakes, but it was remarkable for one reason: it was the world's first vehicle using an internal combustion engine fueled by gasoline. It was tested in Vienna in September of 1870 and put aside. In 1888 or 1889, he built a second automobile, this one with seats, brakes, and steering, and included a four-stroke engine of his own design. That design may have been tested in 1890. Although he held patents for many inventions, he never applied for patents for either design in this category.

The four-stroke engine already had been documented and a patent was applied for in 1862 by the Frenchman Beau de Rochas in a long-winded and rambling pamphlet. He printed about three hundred copies of his pamphlet and they were distributed in Paris, but nothing came of this, with the patent application expiring soon afterward and the pamphlet disappearing into obscurity.

Most historians agree that Nikolaus Otto of Germany built the world's first four-stroke engine although his patent was voided. He knew nothing of Beau de Rochas's patent or idea, and invented the concept independently. In fact, he began thinking about the concept in 1861, but abandoned it until the mid-1870s.

In 1883, Edouard Delamare-Deboutteville and Leon Malandin of France installed an internal combustion engine powered by a tank of city gas on a tricycle. As they tested the vehicle, the tank hose came loose, resulting in an explosion. In 1884, Delamare-Deboutteville and Malandin built and patented a second vehicle. This one consisted of two four-stroke, liquid-fueled engines mounted on an old four-wheeled horse cart. The patent, and presumably the vehicle, contained many innovations, some of which would not be used for decades. However, during the vehicle's first test, the frame broke apart, the vehicle literally "shaking itself to pieces," in Malandin's own words. No more vehicles were built by the two men. Their venture went completely unnoticed and their

patent unexploited. Knowledge of the vehicles and their experiments was obscured until years later.

Production of automobiles begins

Karl Benz

Replica of the Benz Patent Motorwagen built in 1886

Internal combustion engine automobiles were first produced in Germany by Karl Benz in 1885-1886, and Gottlieb Daimler between 1886-1889.

Karl Benz began to work on new engine patents in 1878. At first he concentrated on creating a reliable two-stroke gas engine, based on Nikolaus Otto's design of the four-stroke engine. A patent on the design by Otto had been declared void. Benz finished his engine on New Year's Eve and was granted a patent for it in 1879. Benz built his first three-wheeled automobile in 1885 and it was granted a patent in Mannheim, dated January of 1886. This was the first automobile designed and built as such, rather than a converted carriage, boat, or cart. Among other items Benz invented are the speed

regulation system known also as an accelerator, ignition using sparks from a battery, the spark plug, the clutch, the gear shift, and the water radiator. He built improved versions in 1886 and 1887 and went into production in 1888: the world's first automobile production. His wife, Bertha, made significant suggestions for innovation that he included in that model. Approximately twenty-five were built before 1893, when his first four-wheeler was introduced. They were powered with four-stroke engines of his own design. Emile Roger of France, already producing Benz engines under license, now added the Benz automobile to his line of products. Because France was more open to the early automobiles, more were built and sold in France through Roger than Benz sold in Germany.

In 1886 Gottlieb Daimler fitted a horse carriage with his four-stroke engine. In 1889, he built two vehicles from scratch as automobiles, with several innovations. From 1890 to 1895 about thirty vehicles were built by Daimler and his assistant, Wilhelm Maybach, either at the Daimler works or in the Hotel Hermann, where they set up shop after falling out with their backers. Benz and Daimler, seem to have been unaware of each other's early work and worked independently. Daimler died in 1900. During the First World War, Benz suggested a co-operative effort between the two companies, but it was not until 1926 that the they united under the name of Daimler-Benz with a commitment to remain together under that name until the year 2000.

In 1890, Emile Levassor and Armand Peugeot of France began producing vehicles with Daimler engines, and so laid the foundation of the motor industry in France. They were inspired by Daimler's Stahlradwagen of 1889, which was exhibited in Paris in 1889.

The first American car with a gasoline internal combustion engine supposedly was designed in 1877 by George Baldwin Selden of Rochester, New York, who applied for a patent on an automobile in 1879. Selden did not build an automobile until 1905, when he was forced to do so, due to a lawsuit threatening the legality of his patent because the subject had never been built. After building the 1877 design in 1905, Selden received his patent and later sued the Ford Motor Company for infringing upon his patent. Henry Ford was notorious for opposing the American patent system and Selden's case against Ford went all the way to the Supreme Court, which ruled that Ford, and anyone else, was free to build automobiles without paying royalties to Selden, since automobile technology had improved so significantly since the design of Selden's patent, that no one was building according to his early designs.

In Britain there had been several attempts to build steam cars with varying degrees of success with Thomas Rickett even attempting a production run in 1860.One of the major problems was the poor state of the road network. Santler from Malvern is recognised by the Veteran Car Club of Great Britain as having made the first petrol powered car in the country in 1894 followed by Frederick William Lanchester in 1895 but these were both one-offs. The first production vehicles came from the Daimler Motor Company founded in 1896 and making their first cars made in 1897.

Innovation

Ford Model T, 1927

Nicolas-Joseph Cugnot, a French inventor, is credited for having built the world's first self-propelled mechanical vehicle or automobile in 1765. The first automobile patent in the United States was granted to Oliver Evans in 1789 for his "Amphibious Digger". It was a harbor dredge scow designed to be powered by a steam engine and he built wheels to attach to the bow. In 1804 Evans demonstrated his first successful self-propelled vehicle, which not only was the first automobile in the US but was also the first amphibious vehicle, as his steam-powered vehicle was able to travel on wheels on land as he demonstrated once, and via a paddle wheel in the water. It was not successful and eventually was sold as spare parts.

The Benz Motorwagen, built in 1885, was patented on 29 January 1886 by Karl Benz as the first automobile powered by an internal combustion engine. In 1888, a major breakthrough came when Bertha Benz drove an automobile that her husband had built for a distance of more than 106 km (about 65 miles). This event demonstrated the practical usefulness of the automobile and gained wide publicity, which was the promotion she thought was needed to advance the invention. The Benz vehicle was the first automobile put into production and sold commercially. Bertha Benz's historic drive is celebrated as an annual holiday in Germany with rallies of antique automobiles.

In 1892 Rudolf Diesel got a patent for a "New Rational Combustion Engine" by modifying the Carnot Cycle. And in 1897 he built the first Diesel Engine.

On 5 November 1895, George B. Selden was granted a United States patent for a two-stroke automobile engine (U.S. Patent 549160). This patent did more to hinder than encourage development of autos in the United States. Steam, electric, and gasoline powered autos competed for decades, with gasoline internal combustion engines achieving dominance in the 1910s.

Ransom E. Olds, the creator of the first automobile assembly line

The large-scale, production-line manufacturing of affordable automobiles was debuted by Ransom Eli Olds at his Oldsmobile factory in 1902. This assembly line concept was then greatly expanded by Henry Ford in the 1910s. Development of automotive technology was rapid, due in part to the hundreds of small manufacturers competing to gain the world's attention. Key developments included electric ignition and the electric self-starter (both by Charles Kettering, for the Cadillac Motor Company in 1910-1911), independent suspension, and four-wheel brakes.

Although various pistonless rotary engine designs have attempted to compete with the conventional piston and crankshaft design, only Mazda's version of the Wankel engine has had more than very limited success.

Model changeover and design change

Since the 1920s nearly all cars have been mass-produced to meet market needs, so marketing plans have often heavily influenced automobile design. It was Alfred P. Sloan who established the idea of different makes of cars produced by one firm, so that buyers could "move up" as their fortunes improved. The makes shared parts with one another so that the larger production volume resulted in lower costs for each price range. For example, in the 1950s, Chevrolet shared hood, doors, roof, and windows with Pontiac;

the LaSalle of the 1930s, sold by Cadillac, used the cheaper mechanical parts made by the Oldsmobile division.

Production statistics

In 2005, 63 million cars and light trucks were produced worldwide.

Top 15 Motor Vehicle Producing Countries 2005 edit Car and Light Commercial Vehicle Production (1,000 units)

1,000 2,000 3,000 4,000 5,000 6,0007,000 8,0009,000 10,000 11,000 12,000

United States 11,524 Japan 10,064 Germany 5,543 China 5,067 South Korea 3,657 France 3,495 Spain 2,677 Canada 2,624 Brazil 2,375 United Kingdom 1,783

Mexico 1,607 India 1,406 Russia 1,264 Thailand 1,110 Italy 995

Large free trade areas like EU, NAFTA and MERCOSUR attract manufacturers worldwide to produce their products within them reducing currency risks and customs controls and additionally being close to their customers. Thus the production figures do not show the technological ability or business skill of the areas. In fact much, if not most, of Third World countries car production uses Western technology and car models and sometimes complete Western factories are shipped to such countries. This is reflected in patent statistics as well as the location of R&D centers.

The automobile industry is dominated by relatively few large corporations (not to be confused with the much more numerous brands), the biggest of which (by numbers of cars produced) are currently General Motors, Toyota and Ford Motor Company. It is expected that Toyota will reach the No.1 position in 2006. The most profitable per-unit car-maker of recent years has been Porsche due to its premium price tag

Top 15 Motor Vehicle Manufacturing Companies 2005 edit Car and Light Commercial Vehicle Production (1,000 units)

1,000 2,000 3,000 4,000 5,000 6,000 7,000 8,0009,000 10,000

General Motors 9,040 Toyota 7,100 Ford 6,418 Volkswagen Group 5,173 DaimlerChrysler 4,319 PSA Peugeot Citroën 3,375 Honda 3,373 Nissan 3,348 Hyundai-Kia 2,853 Renault-Dacia-Samsung 2,617 Suzuki-Maruti 2,072 Fiat 1,934 Mitsubishi 1,327 BMW 1,323 Mazda 1,285 Total global production: 67,265

Future of the car

The hydrogen powered FCHV (Fuel Cell Hybrid Vehicle) was developed by Toyota in 2005

There have been many efforts to innovate automobile design funded by the NHTSA, including the work of the NavLab group at Carnegie Mellon University. Recent efforts include the highly publicized DARPA Grand Challenge race.

Relatively high transportation fuel prices do not significantly reduce car usage but do make it more expensive. One environmental benefit of high fuel prices is that it is an incentive for the production of more efficient (and hence less polluting) car designs and the development of alternative fuels. At the beginning of 2006, 1 liter of gasoline cost approximately $0.60 USD in the United States and in Germany and other European countries nearly $1.80 USD. With fuel prices at these levels there is a strong incentive for consumers to purchase lighter, smaller, more fuel-efficient cars. Greenpeace, however, demonstrated with the highly fuel efficient SmILE that car manufacturers aren't delivering what they could and thus not supplying for any such demand [citation needed]. Nevertheless, individual mobility is highly prized in modern societies so the demand for automobiles is inelastic. Alternative individual modes of transport, such as Personal rapid transit, could serve as an alternative to automobiles if they prove to be cheaper and more energy efficient.

Lexus LF-A concept car at the 2006 Greater Los Angeles Auto Show

Electric cars operate a complex drivetrain and transmission would not be needed. However, despite this the electric car is held back by battery technology - a cell with comparable energy density to a tank of liquid fuel is a long way off, and there is no infrastructure in place to support it. A more practical approach may be to use a smaller internal combustion (IC) engine to drive a generator- this approach can be much more efficient since the IC engine can be run at a single speed, use cheaper fuel such as diesel, and drop the heavy, power wasting drivetrain. Such an approach has worked very well for railway locomotives, but so far has not been scaled down for car use.

Alternative technologies

The Henney Kilowatt, the first modern (transistor-controlled) electric car.

Increasing costs of oil-based fuels and tightening environmental laws with the possibility of further restrictions on greenhouse gas emissions are propelling work on alternative power systems for automobiles.

Many diesel-powered cars can run with little or no modifications on 100% pure biodiesel. The main benefit of Diesel combustion engines is its 50% fuel burn efficiency compared

with 23% in the best gasoline engines. Most modern gasoline engines are capable of running with up to 15% ethanol mixed into the gasoline fuel - older vehicles may have seals and hoses that could be harmed by ethanol. With a small amount of redesign, gasoline-powered vehicles can run on ethanol concentrations as high as 85%. 100% ethanol is used in some parts of the world using vehicles that must be started on pure gasoline and switched over to ethanol once the engine is running. Most gasoline fuelled cars can also run on LPG with the addition of a heavy propane tank for fuel storage and carburation modifications to heat the liquid to its boiling point before injection into the engine to avoid carburettor icing. LPG produces non-toxic emissions and is a popular fuel for fork lift trucks that have to operate inside buildings.

The first electric cars were built in the late 1800s, prior to combustion engine automobiles, nevertheless attempts at building viable, modern battery-powered electric vehicle began with the introduction of the first modern (transistor controlled) electric car.

Current research and development is centered on "hybrid" vehicles that use both electric power and internal combustion. Research into alternative forms of power also focus on developing fuel cells, Homogeneous Charge Compression Ignition (HCCI), and even using the stored energy of compressed air or liquid nitrogen.

Alternative forms of combustion such as Gasoline Direct Injection (GDI) are starting to appear in production vehicles. GDI is employed in the 2007 BMW MINI.

Design

The 1955 Citroën DS; revolutionary visual design and technological innovation.

The design of modern cars is typically handled by a large team of designers and engineers from many different disciplines. As part of the product development effort the

team of designers will work closely with teams of design engineers responsible for all aspects of the vehicle. These engineering teams include: chassis, body and trim, powertrain, electrical and production. The design team under the leadership of the design director will typically comprise of an exterior designer, an interior designer (usually referred to as stylists) and a color and materials designer. A few other designers will be involved in detail design of both exterior and interior. For example, a designer might be tasked with designing the rear light clusters or the steering wheel. The color and materials designer will work closely with the exterior and interior designers in developing exterior color paints, interior colors, fabrics, leathers, carpet, wood trim and so on.

In 1924 the American national automobile market began reaching saturation. To maintain unit sales, General Motors instituted annual model-year design changes in order to convince car owners that they needed to buy a new replacement each year. Since 1935 automotive form has been driven more by consumer expectations than by engineering improvement.

Safety

Automobile accidents are almost as old as automobiles themselves. Early examples include, Joseph Cugnot, who crashed his steam-powered "Fardier" against a wall in 1771, Mary Ward, who became one of the first document automobile fatalites on August-31, 1869 in Parsonstown, Ireland, and Henry Bliss, one of the United State's first automobile casulties 1899-09-13 in New York City, NY.

Cars have two basic safety problems: They have human drivers who make mistakes, and the wheels lose traction when braking or turning forces are close to a half gravity.

Early safety research focused on increasing the reliability of brakes and reducing the flammability of fuel systems. For example, modern engine compartments are open at the bottom so that fuel vapors, which are heavier than air, vent to the open air. Brakes are hydraulic and dual circuit so that failures are slow leaks, rather than abrupt cable breaks. Systematic research on crash safety started in 1958 at Ford Motor Company. Since then, most research has focused on absorbing external crash energy with crushable panels and reducing the motion of human bodies in the passenger compartment.

Significant reductions in death and injury have come from the addition of Safety belts and laws in many countries to require vehicle occupants to wear them. Airbags and specialised child restraint systems have improved on that.

There are standard tests for safety in new automobiles, like the EuroNCAP and the US NCAP tests. There are also tests run by organizations such as IIHS and backed by the insurance industry.

Despite technological advances, there is still significant loss of life from car accidents: About 40,000 people die every year in the U.S., with similar figures in Europe. This figure increases annually in step with rising population and increasing travel if no measures are taken, but the rate per capita and per mile travelled decreases steadily. The death toll is expected to nearly double worldwide by 2020. A much higher number of accidents result in injury or permanent disability. The highest accident figures are reported in China and India. The European Union has a rigid program to cut the death toll in the EU in half by 2010 and member states have started implementing measures.

Automated control has been seriously proposed and successfully prototyped. Shoulder-belted passengers could tolerate a 32G emergency stop (reducing the safe intervehicle gap 64-fold) if high-speed roads incorporated a steel rail for emergency braking. Both safety modifications of the roadway are thought to be too expensive by most funding authorities, although these modifications could dramatically increase the number of vehicles that could safely use a high-speed highway.

Economics and societal impact

The economics of personal automobile ownership go beyond the initial cost of the vehicle and includes repairs, maintenance, fuel, depreciation, the cost of borrowing, parking fees, tire replacement, taxes and insurance. Additionally, there are indirect societal costs such as the costs of maintaining roads and other infrastructure, pollution, health care costs due to accidents and the cost of finally desposing of the vehicle at the end of it's life. The ability for humans to move rapidly from place to place has far reaching implications for the nature of our society. People can now live far from their workplaces, the design of our cities is determined as much by the need to get vehicles into and out of the city as the nature of the buildings and public spaces within the city.

Further reading

Articles relating to Automobile configurations

Car body style and classification

2 plus 2, Antique car, Cabrio coach, Cabriolet, City car, Classic car, Compact car, Compact performance car, Compact SUV, Convertible, Coupé, Coupé convertible, Coupe Utility, Crossover SUV, Custom car, Drophead coupe, Fastback, Full-size car, Grand tourer, Hardtop, Hatchback, Hot hatch, Hot rod, Large family car, Leisure activity vehicle, Liftback, Limousine, Luxury car, Microcar, Mid-size car, Mini SUV, Minivan, Multi-purpose vehicle, Muscle car, Notchback, Personal luxury car, Pickup truck, Retractable hardtop, Roadster, Sedan, Saloon, Small family car, Sport compact, Sports car, Sport utility vehicle, Spyder, Station wagon, Estate car, Supermini, Targa top, Taxicab, Touring car, Town car, T-top, Ute, Van, Voiturette

Specialised vehicles Amphibious vehicle, Driverless car, Gyrocar, Flying car.

Fuel technologies

Internal combustion engine, Electric vehicle, Neighborhood electric vehicle, Hybrid vehicle, Battery electric vehicle, Hydrogen vehicle, Fuel cell, Plug-in hybrid electric vehicle, Steam car, Alternative fuel cars, Biodiesel, Gasohol, Ethanol, LPG (Propane), Homogeneous Charge Compression Ignition, Liquid Nitrogen, Gasoline Direct Injection

Driven wheels Two-wheel drive, Four-wheel drive, Front-wheel drive, Rear-wheel drive, All-wheel drive

Engine positioning Front engine, Rear engine, Mid engine

Layout FF layout, FR layout, MR layout, MF layout, RR layout

Engine configuration

Internal combustion engine, Straight-6, V engine, Wankel engine, Reciprocating engine, Inline engine, Flat engine, Flathead engine, Diesel engine, Two-stroke cycle, Four-stroke cycle, Pushrod engine, Straight engine, H engine, Turbodiesel, Hybrid vehicle, Rechargeable energy storage system, Electric vehicle, Hydrogen vehicle

Articles relating to Parts of Automobiles

Framework

A-pillar, Bumper, Cabrio coach, Chassis, Crumple zone, Body-on-frame, Dagmar bumpers, Fender, Fender skirts, Grille, Hood, Hood scoop, Monocoque construction, Pontoon fenders, Quarter panel, Shaker scoop, Spoiler, Subframe, Tonneau

Doors Butterfly doors, Gull-wing door, Scissor doors, Suicide door

Glass Sunroof, Greenhouse, Windshield

Body

Other Antenna ball, Bumper sticker, Hood ornament, Japan Black paint, Monsoonshield, Nerf bar, Truck accessory

Lighting Daytime running lamp, Headlamp, Headlight styling, Hidden headlamps, High intensity discharge, Retroreflector, Sealed beam, Trafficators

Exterior Equipment

Other British car number plates, Distance sensor, US and Canadian license plates, Vanity plate, Vehicle registration plate, Windscreen wiper, Windshield washer fluid

Air/Fuel

Air filter, Automatic Performance Control, Blowoff valve, Boost, Boost controller, Butterfly valve, Carburetor, Charge cooler, Centrifugal type supercharger, Cold air intake, Engine management system, Engine Control Unit, Forced induction, Front mounted intercooler, Fuel filter, Fuel injection, Fuel pump, Fuel tank, Gasoline direct injection, Indirect injection, Intake, Intercooler, Manifold, Manifold vacuum, Mass flow sensor, Naturally-aspirated engine, Ram-air intake, Scroll-type supercharger, Short ram air intake, Supercharger, Throttle body, Top mounted intercooler, Turbocharger, Turbocharged Direct Injection, Twin-turbo, Variable Length Intake Manifold, Variable geometry turbocharger. Warm air intake

Car engine

Exhaust Catalytic converter, Emissions control devices, Exhaust pipe, Exhaust system, Glasspack, Muffler, Oxygen sensor

Cooling Aircooling, Antifreeze, Ethylene glycol, Radiator, Thermostat

Ignition system Starter, Car battery, Contact breaker, Distributor, Electrical ballast, Ignition coil, Lead-acid battery, Magneto, Spark-ignition, Spark plug

Other

Balance shaft, Block heater, Crank. Cam, Camshaft, Connecting rod, Combustion chamber, Crank pin, Crankshaft, Crossflow cylinder head, Crossplane, Desmodromic valve, Engine knocking, Compression ratio, Crank sensor, Cylinder, Cylinder bank, Cylinder block, Cylinder head, Cylinder head porting, Dump valve,Engine balance, Oil filter, Firing order, Freeze plug, Gasket, Head gasket, Hypereutectic piston, Hydrolock, Lean burn, Main bearing, Motor oil, Multi-valve, Oil sludge, Overhead camshaft, Overhead valve, PCV valve, Piston, Piston ring, Pneumatic valve gear, Poppet valve, Power band, Redline, Reverse-flow cylinder head, Rocker arm, Seal, Sleeve valve, Starter ring gear, Synthetic oil, Tappet, Timing belt, Timing mark, Top dead centre, Underdrive pulleys, Valve float, Variable valve timing

Instruments

Backup camera, Boost gauge, Buzzer, Car computer, Carputer, Fuel gauge, Global Positioning System, Idiot light, Malfunction Indicator Lamp, Navigation system, Odometer, Speedometer, Tachometer, Trip computer

Controls Bowden cable, Cruise control, Electronic throttle control, Gear stick, Hand brake, Manettino dial, Steering wheel, Throttle,

Motor vehicle theft deterrence

Car alarm, ESITrack, Immobiliser, Klaxon, Vehicle tracking system, VIN etching

Interior equipment

Passenger safety & seating

Airbag, Armrest, Automatic seatbelt, Bench seat, Bucket seat, Child safety lock, Dicky seat, Passive safety, Rumble seat, Seat belt

Other Air conditioning, Ancillary power, Car audio, Car phone, Center console, Dashboard, Motorola connector, Power window, Rear-view mirror, TripSense

Wheels and Tires

All-terrain tyre, Bias-ply tire, Contact patch, Custom wheel, Drive wheel, Hubcap, Magnesium alloy wheel, Mud-terrain tyre, Paddle tires, Radial tire, Rostyle wheel, Run flat tires, Schrader valve, Slick tire, Spinner, Tire code, Tread, Treadwear rating, Whitewall tire, Wire wheels

Transmission

Automatic transmission, Clutch, Continuously variable transmission, Differential, Driveshaft, Electrorheological clutch, Epicyclic gearing, Fluid coupling, Fully-automatic transmission, Gear stick, Gearbox, Hydramatic, Limited slip differential, Locking differential, Manual transmission, Roto Hydramatic, Saxomat, Semi-automatic transmission, Semi-automatic transmission, Super Turbine 300, Tiptronic Torque converter, Transmission (mechanics), Transmission Control Unit, Turbo-Hydramatic, Universal joint

Steering

Ackermann steering geometry, Anti-lock braking system, Camber angle, Car handling, Caster angle, Oversteer, Power steering, Rack and pinion, Toe angle, Torque steering, Understeer

Suspension

Axle, Beam axle, Coil spring, De Dion tube, Double wishbone, Electronic Stability Control, Hydragas, Hydrolastic, Hydropneumatic suspension, Independent suspension, Kingpin, Leaf spring, Live axle, MacPherson strut, Multi-link suspension, Panhard rod, Semi-trailing arm suspension, Shock absorber, Sway bar, Swing axle, Torsion beam suspension, Transaxle, Trailing arm, Unsprung weight, Watt's linkage, Wishbone suspension

Powertrain

Brakes

Anti-lock braking system, Disc brake, Drum brake, Hand brake, Hydraulic brake, Inboard brake, Brake lining, Brake fade, Brake fluid, Hydraulic fluid, Brake bleeding, Engine braking, Electronic brakeforce distribution, Regenerative brake

Art car

"Animal print" art car, with owner dressed in matching motif.

An art car is a vehicle that has its appearance modified as an act of personal artistic expression. Art car owners often dress in a matching motif (much like their previous generation hippie counterparts) when displaying their cars.

Also, well known artists like Roy Lichtenstein, Andy Warhol etc. have designed BMW Art cars, mainly racing cars like the BMW V12.

Overview

seen in Minnesota

Art cars are public and mobile expressions of the artistic need to create. In creating an art car, the

"exteriors and interiors of factory-made automobiles are transformed into expressions of individual ideas, values, beliefs and dreams. The cars range from

imaginatively painted vehicles to extravagant fantasies whose original bodies are concealed beneath newly sculptured shells" (from Petersen Automotive Museum's Spring 2003 Los Angeles, California exhibit Wild Wheels: Art for the Road Gallery Guide)

In the U.S. the Art Car movement is strongest throughout Texas and the Southeast, in the Minnesota/Wisconsin area, and on the west coast. Art Cars are least evident in the Northeast, although there is a large Baltimore show. In Canada, Art Cars are popular in British Columbia and also in the western Canadian plains (see Artcar Society of Canada) with shows in Nanaimo, B.C. and Regina, SK.

History

Humankind's fascination with decorating vehicles probably predates the custom of Roman charioteers adorning their chariots with objects of a personal nature. More recently, in the Roaring Twenties people who wished to express their free spirit often decorated old cars ("flivvers") with sexy or bizarre cartoon characters, such as Betty Boop. One can imagine rows of these raffish vehicles pulled up at a roadhouse where gargantuan drinking bouts would be accompanied by uninhibited jazz, lewd dancing, and eventual trips to the 'back seat.'

There is some disagreement as to what precisely started the modern Art Car Movement. It can be seen as a twining together of several influences - the hippie-themed VWs of the late 1960s, the lowrider, as well as a Merry Pranksters' creation, the day-glo schoolbus known as Furthur.

During the late 1960s, singer Janis Joplin had a psychedelic-painted Porsche 356 and John Lennon, a paisley Rolls Royce. Partly in imitation, the late 1960s/early 1970s counterculture featured many Day-Glo painted VW Buses and customized vehicles (e.g. a customized 1977 Cadillac Fleetwood seen in the film Escape From New York).

Artist Larry Fuente was among the first to take motorized applique to the limit with his "Mad Cad." Later, artists' Jackie Harris and David Best contributed their works to the burgeoning movement.

'Cartistry' truly attained unstoppable momentum as a social and artistic movement in the 1990s, on the spur of movies and books with a wide underground following, and the

development of innovative art display venues such as Burning Man.Among the countless latecomers, yet ever-present, has been filmmaker Harrod Blank, who has not only made 3 full-length documentary films on Art Cars, but has made three outstanding arted vehicles himself, and who founded the U.S.'s second largest Art Car festival in the San Francisco Bay Area (q.v.)

A well known early art car used for commercial advertisement was the Oscar Meyer Wienie Wagon -- Later versions were known as the Wienermobile. These are bus-sized vehicles styled to appear as a hot dog on a bun.

Artistic styles

Later themes have become more widely focused and more satirical or dark in theme: the Latte Mobile, the Copper Car, the Carthedral, the Vain Van, Jahmbi the Tiki Bus, the Camera Van, Mirabilis Statuarius Vehiculum, The Grape (Revenge of the Road Kill), Rocket Van, Titanic Limo. One of the funniest and most inventive entries in recent memory was titled "Student Driver:" it featured a telephone pole laminated through one corner of the cabin; a leg with roller skate still attached projecting from one wheel well; and sundry jokey dents and marks of mayhem all over the vehicle. Science fiction themes (monsters, giant insects from Them!, flying saucers) are common crowd pleasers. Expressions of the Gothic and the sublime are not unknown. Surrealism is commonplace. In parades and shows, shtick often includes 'arted' bicycles or motor-scooters or costumed roller-skaters weaving among the art cars. Many Art Car owners are natural-born hams, and incorporate elements of music or street theater in their presentation.

Art cars have been surfaced with stone, with brick, with computer boards, with pennies, with tree bark. There is an ever-expanding search for new frontiers and new effects: spinning windmills, orifices spewing flames, steam, or smoke, things that light up after dark, random noise generators, mini performance stages on roofs, truck beds, skirts. An art cartist is limited only by his/her imagination. Sympathetic souls often turn up to compensate for gaps in technical expertise, enabling the artist to reach beyond perceived physical limitations and achieve an artistic triumph. Providing an example of the unexpected and wondrous, Art Cars bring surprise and laughter wherever they roam, helping to defuse road rage on the congested highways of the U.S.A. As one Cartist said, "It gets 500 smiles to the gallon."

Some art cars

CaNdid

This 1971 VW Super Beetle was completely repainted by the artist. It took many hours, but CaNdid is covered from top to bottom with the artists comic strip characters; Candid, Mack Duck, and Christof. All of these characters are in various scenarios and costumes on the vehicle. Also a big attraction to the car is the glitter (the bumper, hubcaps, character costumes, etc). The artist says that 'glitter is a poor girls' replacement for diamonds. Previously seen in Seattle's Fremont neighborhood, now CaNdid resides in Newport, OR. *Sorry, I'm not well versed on computer speak, so you're going to have to click to see the pics.

Buddha Buggy

Buddha Buggy

A 1987 Honda CRX, the Buddha Buggy features a 1.6 m high detachable Nepalese Buddhist stupa on the roof, with strings of prayer flags running up to the golden pinnacle of the stupa. In back, a 300 mm golden Buddha, holding a miniature pagoda, is flanked by intent Laptop Buddhas. These are but a few of the 50 golden statuettes, mostly on Buddhist or Asian spiritual themes, that adorn the car and stupa. Adding to the effect are twirling yin-yang hubcaps, psychedelic-era stickers, and the vanity license plates, TOOCOOL. Not visible in the image is a 330 mm high porcelain Amitabha Buddha in its niche in the stupa, and paintings of the Buddha], comic dragons, a cartoon portrait of the owner, comets, a flying saucer with 2 green aliens, and toothy, two-legged fishes. The

car's interior includes a velvet altarcloth-draped dashboard with brass Tibetan incense burners, statues, and gold tassels; a painted explosion of cosmic love inside the doors; and a temporary installation of spiritual beings meditating in a circle in the back cargo area. The Buddha Buggy is the work of its Seattle, Washington owner, Larry Neilson, and his many collaborators. It has appeared at Art Car events all over the western U.S. and Canada, including the Tacoma_Art_Museum and San Jose (CA) Museum of Art.

Camera Van

A van entirely covered with photographic and videocameras and featuring a video display, built by filmmaker and art car guru Harrod Blank. This vehicle has the distinction of being one of the few works of art that actually looks back at the viewer, as it photographs and videotapes them using some of the cameras mounted upon it, and has the ability to play the video back on the external screen, allowing you to watch it - watching you as you are watching it watch you.

Flying Saucer

This is an otherwise conventional VW Beetle but with aluminum arching skirts all around that make the platform completely circular. In place of the sun roof is somewhat hemispherical transparent plastic dome.

Further and Furthur

The Day-Glo painted schoolbus Furthur is a remake of the original, the Merry Pranksters' hippie bus whose destination sign read simply Furthuur and which "tootled the multitudes" in 1964 in 'real life' and in Tom Wolfe's book The Electric Kool Aid Acid Test.

"The painting job, meanwhile, with everybody pitching in in a frenzy of primary colors, yellow, oranges, blues, reds, was sloppy as hell, except for the parts Roy Seburn did, which were nice manic mandalas. Well, it was sloppy, but one thing you had to say for it; it was freaking lurid. The manifest, the destination sign in the front, read: "Furthur," with two u's." -- from The Electric Kool Aid Acid Test

The bus is also prominently mentioned in the Grateful Dead's song "(That's it for) The Other One", as "the bus to never-ever land" with "...Cowboy Neal (Neal Cassady) at the wheel...".

General Carbuncle

This sculpture by artist James Robert Ford involved transforming a second-hand Ford Capri into the General Lee, from the Dukes of Hazzard, by covering it in little toy cars. Over four thousand toy cars were used, many of which were donated to the artist from people all over the world. The donator could leave a little message in the toy car, or mark it in some way, so they actually become part of the art whilst contributing to the sculpture. General Carbuncle official website.

Guitcycle

This art car is fashioned on a motorcycle chassis, and appears to be a large guitar. The Guitcycle is used as a promotional tool to help raise money, for a charity that buys guitars for young music students that need them.

The H-WIng at 20th Century Fox Studios.

H-Wing Carfighter

A "next generation" art car is the H-Wing Carfighter, a science fiction-themed 1995 Honda Civic del Sol SI two-seater. Designed after a Rebel Alliance A-Wing fighter from Star Wars, it features external laser cannons, lighting effects and an automated R2-D2 "Astromech droid". The interior features computers and other gadgetry. Many modifications are made from "found" parts including sports equipment, plumbing fixtures, and toys. The overall design blends elements of real war machines through the

ages, such as World War Two fighter planes, with the fictional. H-Wing is a member of Road Squadron, a collection of science fiction-related art cars, and generated a great deal of web traffic when featured on Fark.com and Slashdot (see Slashdot effect).

The Nevada Car

Built on an International Harvester pickup truck as a community project during Reno, Nevada's Reno Days event under the direction of David Best. Features a "supercharger" on the hood which is actually the motor head unit from a Kirby Sani-Tronic vacuum cleaner. Owned and (formerly) driven by Patrick Dailey of Novato, California, who states: " Wherever we go people are always trying to give us more junk to put on it." and "...we hardly ever have to buy our own gas." As of summer 2005 the Nevada Car is stored in Boulder City, Nevada, in need of engine repairs.

Oh my God!

A 1965 Volkswagen Beetle with the California license plate OMYGAWD, which features exotic plastic fruits and vegetables, a world globe and the phrase "Oh my God" painted in dozens of languages. A creation of Harrod Blank, this Beetle was featured in the 1992 documentary Wild Wheels (the documentary featured a scene in a courtroom where Blank was seen contesting a parking citation on the contention that art cars and their respective artists were usually subjected to police harassment).

Phone Car

"Teleman" and the Phone Car

Created by business owner, Howard Davis (seen here as his alter-ego, Teleman), as a way to promote his business telephone company. It was featured in various magazines including Motor Trend and Weekly World News, and was also in the Petersen Automotive Museum in Los Angeles for its exhibit on art cars.

The Phone Car is built on a 1975 Volkswagen Beetle frame and has a tinted glass windshield which allows the driver to see clearly out of it. It also has a telephone ringer as its horn, so instead of a honk, it rings!

Purple Haze

Purple Haze.

This Rover Mini was painted in 2 days from its original metallic blue paint to this psychedelic paintwork. The twisted ribbons down the sides represent strands of DNA, the CND symbol on the bonnet is contained within the sun, indicating that nuclear power should be replaced with solar energy. Each hubcab featured a different circular design: A smiley face, a mushroom, a spiral and a Yin-Yang symbol. The number 69 was included (in race car style) to represent the year of Woodstock.

Rocket Car

A car that looks like a Buck Rogers style art deco rocket ship, complete with a gauge-filled cockpit interior which appears to be suitable for a jet aircraft.

The Worthington Bottle Car

One of the earliest examples are the Bottle Cars built in the 1920s to advertise Worthington Beer in England. The five cars were fitted out with boiler plate bodies to resemble the shape of a bottle laid on its side - each one weighed about 2.3 tons.

Art bike

An art bike at the Burning Man Festival, Nevada USA

Art bikes are increasingly popular in the Summer Solstice Parade & Pageant, held annually in Fremont, Washington.

An art bike is generally considered to be any bicycle modified for creative purposes while still being ridable. It is considered a type of kinetic sculpture. The degree of artistic creativity and original or new functionality of art bikes varies greatly depending on the artist or designer's intentions (as well as the subjective interpretation of what "art" is by the observer).

Examples

• The annual Burning Man festival (held in the Black Rock desert of Nevada, USA) is a popular setting for members of the art bike community to display and ride their sometimes radically modified and decorated bicycles.

• The Dekochari is a form of art bike indigenous to Japan.

• A cycle rickshaw is a bicycle designed to carry passengers; in countries like Bangladesh, India, Japan and South Africa these cycle rickshaws may feature elaborate decorations and can be considered art bikes.

• Clown bikes and tall bikes are forms of art bikes.

• "Pimp My 'Fahrrad'" is a German TV show featuring "pimped" bicycles especially modified for urban environments.

Clown bicycle A clown bicycle or clown bike is designed for comedic visual effect or stunt riding. Sometimes called a circus bike.

Types of clown bike

• bucking bike (with one or more eccentric wheels); • tall bike (often called an upside down bike, constructed so that the pedals, seat and

handlebars are all higher than normal) • Come-apart bike, (essentially a unicycle, plus a set of handlebars attached to forks

and a wheel).

Some clown bikes are also built that are directly geared, with no freewheeling, so that they may be pedaled either forward or backwards. Some are built very small but are otherwise relatively normal. Pedaling an extremely small bicycle is very difficult and usually much slower than walking, so there is little practical advantage to having a bicycle that will fit in one's purse or pocket.

Some bikes are built so that the frame or other parts appears to be made of junk or found objects: Bongo the Clown built several bikes which were as much kinetic sculptures as transport, used in parades by members of The North Valley Clown Alley.

Tall bike

A modern home constructed tall bicycle

A Tall Bike is an unusually tall bicycle, typically built for the purpose of fun and recreation, though with occasional practical use.

Modern tall bikes are most commonly constructed by individuals from spare parts. Two conventional bicycle frames are connected, by welding, brazing, or other means, one atop the other. The drivetrain is reconfigured to connect to the upper set of pedals, and the controls are moved to the upper handlebar area.

Alternatively, a bicycle can be built by inverting the frame, and inserting the forks from the 'wrong side', flipping the rear wheel, and adding a long gooseneck and tall handlebars, then welding a long seatpost tube to the 'bottom' (now the top) of the frame. This type of tall bike is made with only one bike frame, and is often called an upside-down bike rather than a tall bike, though the seat can be quite high, depending on the frame shape used. This type can be somewhat safer, as there is less tubing between the rider's legs and dismounting in a hurry can be easily accomplished.

Tall bikes are a popular mode of transportation for modern 'bicycle clubs' (SCUL, Rat Patrol, Zoobomb,Black Label Bike Club, Dead Baby Bikes, CHUNK 666, etc.) and activist groups. They are also a mainstay among builders of Clown bikes, art bikes, Clown alleys and parade groups. Bicycle modification is considered a fun and cheap hobby, and never fails to attract a lot of attention. Most modern cities contain large quantities of unused or abandoned bicycles that provide the raw materials for tall bikes and other mutant cycles.

Practical Uses

Tall bikes can be used for general transportation and recreation, just like other bicycles. Regular tall-bike commuters note that both their increased visibility and the simple 'wow factor' gives them a safety advantage in automobile traffic over 'short bikes.'

A Giraffe Lamplighter Bicycle, manufactured in 1898

Historically, one of the the first practical uses of the tall bike was as a late 1800's lamp lighting system, by which a worker would mount a specialized tall bicycle while equipped with a torch for lighting gas lamps. As the worker rode to each lamp, they would lean against the lamp post, light the lamp, and then ride to the next. Upon completing the circuit of lamps, an assistant would help the rider dismount.

Sporting

Tall bike jousting is a popular sport among bicycle hackers. Combatants arm themselves with lances, and attempt to score points by dislodging the other rider. Rules vary by area, and with the mood of the combatants. Like the ancient sport of jousting, this is a sport where honor plays a role and dishonorable wins are frowned upon.

Gentle rules: Foam pool noodles can be used as lances, and points may be scored by delivering a touch to the chest.

More intense rules: PVC pipe with foam covering can be used as lances, and points may be scored by causing the other rider to fall off their tall bike.

Very intense rules: Metal pipes or pieces of wood may be used as lances, and points may be scored by knocking the other rider off their bicycle, and/or damaging their bicycle or causing an injury.

Fire jousting: The foam ends of the lances are set alight. A dangerous and spectacular variation.

Jar Rules: Riders mount tall bike with a lance, metal or wood, with a jam jar placed on the tip called a jarry. Points are scored when the jar is broken. Riders then can choose to battle with the broken jam jar, or replace it. Battle continues until all the jars are broken, or an opponent is retired.

Design Considerations

Tall bikes present some interesting design considerations, and different localities tend to have different methods of dealing with them.

One consistent issue is that the seat tends to end up in line with, or behind, the rear axle, which creates a powerful tendency to lift the front wheel of the bicycle on acceleration. Some bicycle builders simply accept this tendency, but others solve the problem by moving the seat post forward, lowering the handlebars, or by using a smaller wheel in front, typically a 24" instead of a 26".

Stability can also be negatively affected, and enhancements such as extended wheelbase by welding extensions on the front and rear dropouts can benefit stability. Contest holders often place restrictions on such modification to prevent unfair advantages.

Car modding

Tuned Kia Rio, with bespoke alloys, spoiler and tinted glass

Car modding is when a vehicle (usually a passenger car) is modified in an attempt to make it look better, to have better performance, or both. Major areas of modification include engine performance tuning, suspension enhancement or modification, exterior modification, and interior modification.

Areas of modification

Engine tuning

Engine tuning involves modifications designed to increase the power of the engine. These modifications can range from a simple chip tuning, to adding nitrous injection, to a complete engine swap.

"Tuning an engine" has many different meanings today. Traditionally, to actually tune an engine meant adjusting the timing and the air/fuel ratios. Today, many people consider tuning to be adding cold air intakes, exhaust systems, turbochargers, or any other part that could conceivably make the car faster. It is important to note that the two different meanings behind the word tuning refer to two completely different methods of making a car faster.

Adjusting engine timing and air/fuel ratios generally improves power and reliability of an engine without any futher modifications. On the other hand, tuning an engine becomes incredibly beneficial after already heavily modifying the engine with upgrades, like forced induction (including nitrous) or adjusting the internal parts to increase engine compression.

The second meaning is actually an incorrect use of the word tuning. Adding parts to increase horsepower and torque is not actually tuning, but physically modifying the vehicle and its engine.

Suspension tuning

Suspension tuning involves modifying the feathers/springs and shock absorbers of a vehicle. Here shorter feathers/springs and stronger shock absorbers are mostly used, in order to reduce body roll during cornering. Often the vehicle is lowered somewhat, reducing the vehicle's clearance.

For offroad vehicles, the emphasis is on lengthening the suspension to increase clearance.

Lowriders with hydraulic suspensions are another unique kind of suspension tuning.

Body tuning

Body tuning involves adding or modifying spoilers and a body kit. Sometimes this is done to improve the aerodynamic performance of a vehicle. More often, these modifications are done mainly to improve a vehicle's appearance.

Interior modifications

Interior modifications often call for a change or upgrade from factory-installed equipment. Seats may be upgraded for performance or styling reasons. Some car modifiers add such products as lava lamps or electric balls to make the car look classy or different to other modified cars.

One common type of interior modification is the addition of multimedia devices, for example amplifiers, speakers and subwoofers, DVD players, etc. Another type of multimedia is small television playing.

Terms

"Pimped" cars are usually classic convertibles.

"Streeted" cars are Japanese imports, such as a Toyota Supra or Lancer Evolution series, these cars are most commonly modified with the more expensive mods available. The most popular modifications include neon lights and vinyl stickers.

"Tasteless" car modifications

Cars are often modified in a manner that is considered to be "tasteless or unsightly ", an example of this being bright colors and low-cost exterior/interior modifications. Tasteless car modifications are one of the components of the British stereotype of the "chav". Note that the crucial aspect of car modding associated with this stereotype is its superfical nature (Bean can tail pipes, cheap "blow-over" paint jobs, redundant spoilers etc.). Other British subcultures engage in car modding, with the focus on "under the hood" modifications (customised engines, brakes etc.), without incurring the same criticism or condescension.

Cutdown

Skinhead with Cutdown

Cutdown is a term referring to a customised scooter (usually Vespa or Lambretta), which has had parts of the bodywork removed or cut away.

Cutdowns were popular in the 1970s and 1980s with skinheads and scooterboys. Many of the scooters are cut down to improve power to weight ratio, and tuned (much like a four-wheeled hot rod). Some cutdowns are used to drag race.

Power-to-weight ratio Power-to-weight ratio (sometimes referred to as the more general Specific power) and its inverse weight-to-power ratio are measures commonly used when comparing various vehicles (or engines), including automobiles, motorcycles, aircraft, and armoured fighting vehicles. It is the power the engine generates, divided by the vehicle's (or engine) weight or vice versa:

Units are usually horsepower per tonne (hp/tonne - PtW) or kilograms per horsepower (kg/hp - WtP), although nowadays watts are used for power in most countries that adopted the metric system

The power-to-weight ratio is often used as an indication of likely performance. The larger the PtW (the smaller the WtP) the more performance can be expected. Vehicle weights have relatively little impact on top speed, which is mostly dependent on aerodynamic drag (see drag equation). Acceleration (a), on the other hand, is dominated by the Newtonian acceleration term, F = ma, so more force (F - from the engine's torque delivered to the driven wheels or thrust delivered by an aircraft engine), will deliver more acceleration for any given vehicle mass (m = weight/g).

In any vehicle the engine power-to-weight ratio is essential for vehicle power-to-weight ratio. But in an aircraft it is more critical than in any other vehicle because any additional weight requires more lift to be generated by the wings in order to lift it. More lift from the wings automatically means more drag, through a process known as induced drag, slowing the plane down. Thus if any two engines deliver the same power, the lighter one will result in a better plane. Power-to-weight ratio therefore has a much more important impact on overall performance in aircraft, including top speed.

In this usage the power-to-weight ratio is typically used to refer to the weight of the engine alone, as a useful way of comparing various aircraft engines. The term applying to the aircraft as a whole is power loading, and is used especially in helicopter engineering.

Power-to-weight ratio is also often used as a general indicator of the mobility of tanks and other armoured fighting vehicles, usually expressed in horsepower per tonne (hp/t). Such vehicles, weighing up to seventy tons, must be able to achieve relatively high speeds quickly, while overcoming a great deal of inertia and mechanical resistance even on hard surfaces, and also travel at high speeds over soft ground and up steep slopes.

Porting (engine) In motor racing, porting is the modification of the shape and size of the engine's ports (that portion of the intake and exhaust systems which is within the engine castings) for enhanced aerodynamic flow. This allows for greater volumes of air/fuel mixture to be smoothly entered into the compression chamber.

Car tuning

It has been suggested that Car modding be merged into this article or section. (Discuss)

Car tuning is both an industry and a popular hobby, in which a car is modified in order to improve its performance.

Car tuning is related to auto racing, but most performance cars never compete. Rather they are built for display at motor shows and club meetings, or just for the pleasure of owning and driving such a vehicle.

The focus of many car tuners is the engine (see engine tuning), but the transmission, suspension and brakes are often modified as well.

Another major part of tuning a car is the body work. This includes changing front, side and rear bumpers, adding spoilers, alloy wheels window tinting, neon lights, sound systems, seats and just about everything else that you can change in a car.

Engine tunings Engine tuning or engine building is the adjustment, modification or design of internal combustion engines to yield more performance, either in terms of power output or economy. It is a popular pastime with amateur mechanics or "gearheads" and "petrolheads". It has a long history, almost as long as the development of the car in general, originating with the development of early racing cars, and later, with the post-war hot-rod movement.

Tuning can describe a wide variety of adjustments and modifications, from the routine adjustment of the carburetor and ignition system to significant engine modifications. On older engines, setting the idling speed, mixture, carburetor balance, spark plug and distributor point gaps and ignition timing were both regular tasks on all engines and the final but essential steps in setting up a racing engine. On modern engines some or all of these tasks are automated.

At the other end of the scale, performance tuning of an engine can involve revisiting some of the design decisions taken at quite an early stage in the development of the engine.

Performance tuning

Performance tuning focusses on the tuning of an engine for motor sport, although many cars built by hobbyists never compete but are rather built for display at motor shows or the simple pleasure of owning and driving such a car. In this context (and depending on the particular event), the power output, torque and responsiveness of the engine are of premium importance, but reliability and economy are also relevant. To win, a car must complete the event. This means the engine must be strong enough to do so, often far stronger than the production design on which it is based, and also that the vehicle must carry sufficient fuel. The weight of this fuel will affect the overall performance of the car, so fuel economy is a competitive advantage.

This also means that the performance tuning of an engine should take place in the context of the development of the overall vehicle. In particular, transmission, suspension and brakes must match the performance of the engine, otherwise the car will be unreliable, uncompetitive, and perhaps extremely dangerous.

In most cases, people are interested in increasing the power output of an engine. Many well tried and tested techniques have been devised to achieve this, but essentially all operate to increase the rate (and to a lesser extent efficiency) of combustion in a given engine. This is achieved by putting more fuel/air mixture into the engine, using a fuel with higher energy content, burning it more rapidly, and getting rid of the waste products more rapidly - this increases volumetric efficiency. The specific ways this is done include:

• Increasing the engine displacement. This can be done by "boring" - increasing the diameter of the cylinders and pistons, or by "stroking" - using a crankshaft with a longer stroke (in combination with pistons of shorter compression height, to maintain the original compression ratio), or both.

• Using larger or multiple carburetors, to create more fuel/air mixture to burn, and to get it into the engine more quickly. In modern engines, fuel injection is more often used, and may be modified in a similar manner.

• Increasing the size of the valves in the engine, thus decreasing the restriction in the path of the fuel/air mixture entering, and the exhaust gases leaving the cylinder. Using multiple valves per cylinder results in the same thing - it is often more practical to have several small valves than have larger single valves.

• Using larger bored, smoother, less contorted intake and exhaust manifolds. This helps maintain the velocity of gases. Similarly, the ports in the cylinder can be enlarged and smoothed to match. This is termed "Cylinder head porting", usually with the aid of an air flow bench for testing and verifying the efficacy of the modifications.

• The larger bore may extend right through the complete exhaust system, using larger diameter piping and low back pressure mufflers, and through the intake system, with larger diameter airboxes, high-flow, high-efficiency air filters. Muffler modifications will change the sound of the car's engine, usually making it louder; for some tuners this is in itself a desirable property.

• Increasing the valve opening height (lift), by changing the profiles of the camshaft or the lift (lever) ratio of the valve rockers (OHV engines), or cam followers (OHC engines).

• Optimising the valve timing to improve burning efficiency - usually this increases power at one range of operating RPM at the expense of reducing it at others. For many applications this compromise is acceptable. Again this is usually achieved by a differently profiled camshaft. Four-stroke cycle#Valve Timing, variable valve timing.

• Raising the compression ratio, which makes more efficient use of the cylinder pressure developed and leading to more rapid burning of fuel, by using larger compression height pistons or thinner head gasket or by milling "shaving" the cylinder head.

• Supercharging; adding a supercharger or turbocharger. The fuel/air mass entering the cylinders is increased by compressing the air first, (usually) mechanically.

• Using a fuel with higher energy content or by adding an oxidiser such as nitrous oxide.

• Changing the tuning characteristics electronically, by changing the firmware of the engine management system (EMS). This chip tuning often works because modern engines are designed to give a great deal of raw power, which is then reduced by the engine management system to make the engine operate smoothly over a wider RPM range, with low emissions. By analogy with an operational amplifier, the EMS acts as a feedback loop around an engine with a great deal of open loop gain. Many modern engines are now of this type, and are amenable to this form of tuning. Naturally many other design parameters are sacrificed in the pursuit of power.

The choice of modification depends greatly on the degree of performance enhancement desired, budget, and the characteristics of the engine to be modified. Intake, exhaust, and chip upgrades are usually amongst the first modifications made as they are the cheapest, make reasonably general improvements (whereas a different camshaft, for instance, requires trading off performance at low engine speeds for improvements at high engine speeds), can often actually improve fuel economy, generally do not affect engine reliability too much (because no moving parts are modified), and are in any case essential to take full advantage of any further upgrades.

• Manufacturer Detuned Engines - Changing the tuning characteristics electronically, by changing the firmware of the engine management system (EMS). This chip tuning also works because many manufacturers produce one engine which is used in a range of models and the power and torque characteristics are determined solely by the engine management system software. This allows the manufacturers to sell cars in various markets with different tax and emissions regulations without the huge development cost of designing different engines. Cross platform engine sharing also allows for a single engine to be used by different brands, tuned to suit their particular market.

Examples of models using one engine with different ECU software providing varying specifications:

Volvo V70 D5 Euro IV available as 126 bhp, 163 bhp, 185 bhp, all sharing the same 2.4 turbo diesel engine. Mini One and Mini Cooper available as 90 bhp and 127 bhp respectively, both sharing the same 1.6 normally aspirated engine. Ford Focus ST225 and Volvo S40 T5 both sharing the Volvo 2.5 turbo petrol engines, with different power outputs controlled by the engine management system.

Transmission (mechanics) In mechanics, a transmission or gearbox is the gear and/or hydraulic system that transmits mechanical power from a prime mover (which can be an engine or electric motor), to some form of useful output device.

Explanation

Transmission types

Manual

Automatic

• Tiptronic

Semi-automatic

• Twin-clutch Gearbox

Continuously-variable Multitronic Derailleur gears Hub gears

Early transmissions (gearboxes) included right-angle drives and other gearing in windmills, horse-powered devices, and steam engines, mainly in support of pumping, milling, and hoisting. Most modern gearboxes will either reduce an unsuitable high speed and low torque of the prime mover output shaft to a more useable lower speed with higher torque, or do the opposite and provide a mechanical advantage (i.e increase in torque) to allow higher forces to be generated. However, some of the simplest gearboxes merely change the physical direction in which power is transmitted.

Many systems, such as typical automobile transmissions, include the ability to select one of several different gear ratios. In this case, most of the gear ratios (simply called "gears") are used to slow down the output speed of the engine and increase torque. However, the highest gear(s) may be an "overdrive" type that increases the output speed.

Uses

Gearboxes have found use in a wide variety of different—often stationary—applications. Transmissions are also used in agricultural, industrial, construction, and mining equipment. In addition to ordinary transmission equipped with gears, such equipment makes extensive use of the hydrostatic drive and electrical Adjustable Speed Drives.

Simple transmission

The simplest transmissions, often called gearboxes to reflect their simplicity (although complex systems are also called gearboxes on occasion), provide gear reduction (or, more rarely, an increase in speed), sometimes in conjunction with a right-angle change in direction of the shaft. These are often used on PTO-powered agricultural equipment, since the axial PTO shaft is at odds with the usual need for the driven shaft, which is either vertical (as with rotary mowers), or horizontally extending from one side of the implement to another (as with manure spreaders, flail mowers, and forage wagons). More complex equipment, such as silage choppers and snowblowers, have drives with outputs in more than one direction.

Regardless of where they are used, these simple transmissions all share an important feature: the gear ratio cannot be changed during use. It is fixed at the time the transmission is constructed.

Multi-ratio systems

Many applications require the availability of multiple gear ratio. Often, this is to ease the starting and stopping of a mechanical system, though another important need is that of maintaining good fuel economy.

Automotive basics

The need for a transmission in an automobile is a consequence of the characteristics of the internal combustion engine. Engines typically operate over a range of 600 to about 6000 revolutions per minute (though this varies from design to design and is typically less for diesel engines), while the car's wheels rotate between 0 rpm and around 2500 rpm.

Furthermore, the engine provides its highest torque outputs approximately in the middle of its range, while often the greatest torque is required when the vehicle is moving from rest or travelling slowly. Therefore, a system that transforms the engine's output so that it can supply high torque at low speeds, but also operate at highway speeds with the motor still operating within its limits, is required. Transmissions perform this transformation.

Most transmissions and gears used in automotive and truck applications are contained in a cast iron case, though sometimes aluminum is used for lower weight. There are three shafts: a mainshaft, a countershaft, and an idler shaft.

The mainshaft extends outside the case in both directions: the input shaft towards the engine, and the output shaft towards the rear axle (on rear wheel drive cars). The shaft is suspended by the main bearings, and is split towards the input end. At the point of the split, a pilot bearing holds the shafts together. The gears and clutches ride on the mainshaft, the gears being free to turn relative to the mainshaft except when engaged by the clutches.

Manual transmission

Manual transmissions come in two basic types: a simple unsynchronized system where gears are spinning freely and must be synchronized by the operator to avoid noisy and damaging "gear clash", and synchronized systems that will automatically "mesh" while changing gears. The former type is only used on some rally cars and heavy-duty trucks nowadays.

Manual transmissions dominate the car market outside of North America. They are cheaper, lighter, usually give better performance, and fuel efficiency (although the latest sophisticated automatic transmissions may yield results slightly closer to the ones yielded by manual transmissions), and it is customary for new drivers to learn, and be tested, on a car with a manual gearchange. In Japan, Germany, the UK, Ireland, Sweden and France at least, a test pass using an automatic car does not entitle the driver to use a manual car on the public road unless a second manual test is taken. In most of the other European nations like Italy and the Netherlands, obtaining a driver's license is only possible by passing a driver's test driving a car with manual transmission. Manual transmissions are much more common than automatic transmissions in Asia & Europe.

Automatic transmission

North American cars have an automatic transmission that will select an appropriate gear ratio without any operator intervention. They primarily use hydraulics to select gears, depending on pressure exerted by fluid within the transmission assembly. Rather than using a clutch to engage the transmission, a torque converter is put in between the engine and transmission. It is possible for the driver to control the number of gears in use or select reverse, though precise control of which gear is in use is usually not possible.

Automatic transmissions are easy to use. In the past, automatic transmissions of this type have had a number of problems; they were complex and expensive, sometimes had reliability problems (which sometimes caused more expenses in repair), have often been less fuel-efficient than their manual counterparts and their shift time was slower than a manual making them uncompetitive for racing. With the advancement of modern automatic transmissions this has changed. With computer technology, considerable effort has been put into designing gearboxes based on the simpler manual systems that use electronically-controlled actuators to shift gears and manipulate the clutch, resolving many of the drawbacks of a hydraulic automatic transmission.

Automatic transmissions have always been extremely popular in the United States, where perhaps 19 of 20 new cars are sold with them (many vehicles are not available with manual gearboxes anymore). In Europe automatic transmissions are gaining popularity as well.

Attempts to improve the fuel efficiency of automatic transmissions include the use of torque converters which lock-up beyond a certain speed eliminating power loss, and overdrive gears which automatically actuate above certain speeds; in older transmissions both technologies could sometimes become intrusive, when conditions are such that they repeatedly cut in and out as speed and such load factors as grade or wind vary slightly. Current computerized transmissions possess very complex programming to both maximize fuel efficiency and eliminate any intrusiveness.

For certain applications, the slippage inherent in automatic transmissions can be advantageous; for instance, in drag racing, the automatic transmission allows the car to be stopped with the engine at a high rpm (the "stall speed") to allow for a very quick launch when the brakes are released; in fact, a common modification is to increase the stall speed of the transmission. This is even more advantageous for turbocharged engines, where the turbocharger needs to be kept spinning at high rpm by a large flow of exhaust in order to

keep the boost pressure up and eliminate the turbo lag that occurs when the engine is idling and the throttle is suddenly opened.

Semi-automatic transmission

The creation of computer control also allowed for a sort of half-breed transmission where the car handles manipulation of the clutch automatically, but the driver can still select the gear manually if desired. This is sometimes called "clutchless manual". Many of these transmissions allow the driver to give full control to the computer.

There are some specific types of this transmission, including Tiptronic, Geartronic, and Direct-Shift Gearbox.

There are also sequential transmissions which use the rotation of a drum to switch gears.

Bicycle gearing

Bicycles usually have a system for selecting different gear ratios as well. There are two main types, derailleur gears and hub gears. The derailleur type is the most common, and the most visible, using a number of sprocket gears. Typically there are several gears available on the rear sprocket assembly, attached to the rear wheel. A few more sprockets are usually added to the front assembly as well. Multiplying the number of sprocket gears in front with the number to the rear gives the number of different gear ratios, often called "speeds". A 21-speed bike will have three sprocket wheels in front and seven in back.

Hub gears use epicyclic gearing and are enclosed within the axle of the rear wheel. Because of the small space, they typically only offer a handful of different speeds, although at least one has reached the level of 14 different gear ratios.

Note: add content for bicycle automatic transmissions, ie. (browning transmission, shimano electronic transmission, and modifications of derailer type ala landrider and others.)

Uncommon types

Continuously-variable transmission

The mechanical systems described above only allow a few different gear ratios to be selected, but there does exist a type of transmission that essentially has an infinite number of ratios available. The continuously variable transmission allows the relationship between the speed of the engine and the speed of the wheels to be varied constantly. This can provide even better fuel economy if the engine is constantly running at a single speed. However, this is somewhat disconcerting to drivers, who are accustomed to hearing and feeling the rise and fall in speed of an engine, and the jerk felt when changing gears. Changes to software in the computer control system can simulate these effects, however.

Hydrostatic transmission

Hydrostatic transmissions transmit all power with hydraulics; there is no solid coupling of the input and output. One half of the transmission is a variable displacement pump and the other half is a hydraulic motor. A movable swash plate controls the piston stroke to change the pump's displacement.

They are used in the drive train of some types of heavy equipment, diesel multiple unit trains, and applications requiring continuously variable control (such as riding lawnmowers and lawn tractors). Their disadvantages are high cost and sensitivity to contamination.

Electric transmission

Electric transmissions convert the mechanical power of the engine(s) to electricity with electric generators and convert it back to mechanical power with electric motors. If the generators are driven by turbines, such arrangements are called turbo-electric. Likewise installations powered by diesel-engines are called diesel-electric. Diesel-electric arrangements are used on many railway locomotives.

Suspension (vehicle)

The front suspension components of a Ford Model T.

Suspension is the term given to the system of springs, shock absorbers and linkages that connects a vehicle to its wheels. Suspension systems serve a dual purpose - contributing to the car's handling and braking for good active safety and driving pleasure, and keeping vehicle occupants comfortable and reasonably well isolated from road noise, bumps, and vibrations. These goals are generally at odds, so the tuning of suspensions involves finding the right compromise. The suspension also protects the vehicle itself and any cargo or luggage from damage and wear. The design of front and rear suspension of a car may be different.

Important properties

Spring rate

Spring rate is a major component in setting the vehicles ride height or its location in the suspension stroke. Vehicles which carry heavy loads will often have heavier than desired springs to compensate for the additional weight that would otherwise collapse a vehicle to the bottom of its travel (stroke). Heavier springs are also used in performance applications when the suspension is constantly forced to the bottom of its stroke causing a reduction in the useful amount of suspension travel which may lead to harsh bottoming. This may vary with deflection. For active suspensions, it may depend on other things. The softer the springs, the more important the other requirements are. Spring rate is often a compromise between comfort and handling, but when other things are compromised instead, as in the 1960s Lotus Elan, both may be achieved.

Spring rates typically have units of lbf/in. or N/mm. An example of a linear spring rate is 500 lbf/in. For every inch the spring is compressed, it exerts 500 lbf. A non-linear spring rate (typically increasing) is one that the force exerted increasess exponentially. For example, the first inch exerts 500 lbf, the second inch exerts an additional 550 lbf (for a total of 1050 lbf), the third inch exerts another 600 lbf (for a total of 1650 lbf). In contrast a linear spring compressed to 3 inches will only exert 1500 lbf.

Travel

Travel is the measure of distance from the bottom of the suspension stroke (such as when the vehicle is on a jack and the wheel hangs freely), to the top of the suspension stroke (such as when the vehicles wheel can no longer travel in an upward direction toward the vehicle). Bottoming or lifting a wheel can cause serious control problems or directly cause damage. "Bottoming" can be either the suspension, tires, fenders, etc. running out of space to move or the body or other components of the car hitting the road. The control problems caused by lifting a wheel are less severe if the wheel lifts when the spring reaches its unloaded shape than they are if travel is limited by contact of suspension members.

Damping

Damping (not to be confused with dampening) is the control of motion or oscillation, as seen with the use of hydraulic gates and valves in a vehicles shock absorber. This may also vary, intentionally or unintentionally. Like spring rate, the optimal damping for comfort may be less than for control.

Damping controls the travel speed and resistance of the vehicles suspension. An undamped car will oscillate up and down. With proper damping levels, the car will settle back to a normal state in a minimal amount of time. Most damping in modern vehicles can be controlled by increasing or decreasing the resistance to fluid flow in the shock absorber.

Camber control

Camber changes with wheel travel and with body roll. A tire wears and brakes best perpendicular to the road. Depending on the tire, it may hold the road best at a slightly different angle. Small changes in camber, front and rear, are used to tune handling.

Roll Center Height

This is important to body roll and to relative weight transfer, front and rear. It may affect tendency to rollover. All other things being equal the end of the car with the higher roll center will have more weight transfer and therefore more slip in a turn. However, the roll moment distribution in most cars is set more by the antiroll bars than the RCH.

Flexibility and vibration modes of the suspension elements

In modern cars, the flexibility is mainly in the rubber bushings.

Isolation from high frequency shock

For most purposes, the weight of the suspension components is unimportant, but at high frequencies, caused by road surface roughness, the parts isolated by rubber bushings act as a multistage filter to suppress noise and vibration better than can be done with only the tires and springs. (The springs work mainly in the vertical direction.)

Contribution to unsprung weight and total weight

These are usually small, except that the suspension is related to whether the brakes and differential(s) are sprung.

Space occupied

Designs differ as to how much space they take up and where it is located.

Force distribution

The suspension attachment must match the frame design in geometry, strength and rigidity.

Air resistance (Drag)

Certain modern vehicles have height adjustable suspension in order to improve aerodynamics and fuel efficiency.

Cost

Production methods improve, but cost is always a factor. The continued use of the solid rear axle, with unsprung differential, especially on heavy vehicles, seems to be the most obvious example.

Springs and dampers

All suspensions use springs to absorb impacts and dampers (or shock absorbers) to control spring motions. A number of different types of each have been used:

Passive, Semi Active, and Active Suspensions

Traditional springs and dampers are referred to as passive suspensions. If the suspension is externally controlled then it is a semi-active or active suspension.

Semi-active suspensions include devices such as air springs and switchable shock absorbers, various self-levelling solutions, as well as systems like Hydropneumatic, Hydrolastic, and Hydragas suspensions. Delphi currently sells shock absorbers filled with a magneto-rheological fluid, whose viscousity can be changed electromagnetically, thereby giving variable control without switching valves, which is faster and thus more effective, along with being cheaper. An Australian company, Kinetic, is having (as of 2005) some success with various semi-active systems, which provide adjustable roll control and damping, by using cross linked shock absorbers, and other methods. They have now been bought out by Tenneco and Alcorn.

For example, a hydropneumatic Citroën will "know" how far off the ground the car is supposed to be and constantly reset to achieve that level, regardless of load. It will not instantly compensate for body roll due to cornering however. Citroën's system adds about 1% to the cost of the car versus passive steel springs.

Fully active suspensions use electronic monitoring of vehicle conditions, coupled with the means to impact vehicle suspension and behavior in real time to directly control the motion of the car. Lotus Cars developed several prototypes, and introduced them to F1, where they have been fairly effective, but have now been banned. Nissan introduced a low bandwidth active suspension in circa 1990 as an option that added an extra 20% to the price of luxury models. Citroën has also developed several active suspension models (see Hydractive).

A recently publicised fully-active system from Bose Corporation uses linear electric motors, ie solenoids, in place of hydraulic or pneumatic actuators that have generally been used up until recently.

Springs

• Leaf spring - AKA Hotchkiss, Cart, or semi-elliptical spring • Torsion beam suspension • Coil spring • Rubber bushing • Air spring

Dampers or shock absorbers

The shock absorbers damp out the, otherwise resonant, motions of a vehicle up and down on its springs. They also must damp out much of the wheel bounce when the unsprung weight of a wheel, hub, axle and sometimes brakes and differential bounces up and down on the springiness of a tire. The regular bumps found on dirt roads (nicknamed "corduroy", but properly washboarding) are caused by this wheel bounce. These bumps are more common on US dirt roads, where solid rear axles are common, than they are in e.g. French dirt roads, where unsprung weight tends to be low and suspensions well damped.

Suspension types

Suspension systems can be broadly classified into two subgroups - dependent and independent. These terms refer to the ability of opposite wheels to move independently of each other.

A dependent suspension normally has a live axle (a simple beam or 'cart' axle) that holds wheels parallel to each other and perpendicular to the axle. When the camber of one wheel changes, the camber of the opposite wheel changes in the same way.

An independent suspension allows wheels to rise and fall on their own without affecting the opposite wheel. Suspensions with other devices, such as anti-roll bars that link the wheels in some way are still classed as independent.

A third type is a semi-dependent suspension. In this case, jointed axles are used, on drive wheels, but the wheels are connected with a solid member, most often a deDion axle. This differs from "dependent" mainly in unsprung weight.

Interconnected suspensions (mechanically interconnected, such as anti-roll bars; and hydraulically or pneumatically interconnected, e.g., SAE 2005-01-3593, SAE 2003-01-0312) have also been used to achieve a better compromise among vertical, roll and pitch properties.

Dependent suspensions

Dependent systems may be differentiated by the system of linkages used to locate them, both longitudinally and transversely. Often both functions are combined in a set of linkages.

Examples of location linkages include:

• Trailing arms • Satchell link • Panhard rod • Watt's linkage • WOBLink • Mumford linkage • leaf springs used for location (transverse or longitudinal)

o Fully elliptical springs usually need supplementary location links and are no longer in common use

o Longitudinal semi-elliptical springs used to be common and still are used on some US cars and on trucks. They have the advantage that the spring rate can easily be made progressive (non-linear)

o A single transverse leaf spring for both front wheels and/or both back wheels, supporting solid axles was used by Ford Motor Company, before and soon after World War II, even on expensive models. It had the advantages of simplicity and low unsprung weight (compared to other solid axle designs), as well as the other advantages of solid axles.

In a front engine rear drive vehicle, dependent rear suspension is either "live axle" or deDion axle, depending on whether or not the differential is carried on the axle. Live axle is simpler but the unsprung weight contributes to wheel bounce.

Because it assures constant camber, dependent (and semi-independent) suspension is most common on vehicles that need to cary large loads, as a proportion of the vehicle weight, that have relatively soft springs and that do not (for cost and simplicity reasons) use active suspensions. However the use of dependent front suspension has become limited to a few trucks.

Independent suspensions

The variety of independent systems is greater and includes:

• Swing axle • MacPherson strut/Chapman strut • A arm or wishbone suspension • multi-link suspension • semi-trailing arm suspension • swinging arm • leaf springs

o Two transverse leaf springs, or four quarter elliptics on one end of a car are similar to wishbones in geometry, but are more compliant. Examples are the front of the Panhard Dyna Z and the early examples of Peugeot 403 and the back of the AC Ace and AC Aceca.

Because the wheels are not constrained to remain perpendicular to a flat road surface in turning, braking and varying load conditions, control of the wheel camber is an important issue. Swinging arm was common in small cars that were sprung softly and could carry large loads, because the camber is independent of load. Some active and semi-active suspensions maintain the ride hight, and therefore the camber, independent of load. In sports cars, optimal camber change when turning is more important.

Wishbone and multi-link allow the engineer more control over the geometry, to arrive at the best compromise, than swing axle, MacPherson strut or swinging arm do; however the cost and space requirements may be greater. Semi-trailing arm is in between, being a variable compromize between the geometries of swinging arm and swing axle.

Armoured fighting vehicle suspension

This Grant I tank's suspension has road wheels mounted on wheel trucks, or bogies.

Military AFVs, including tanks, have specialized suspension requirements. They can weigh more than seventy tons and are required to move at high speed over very rough ground. Their suspension components must be protected from land mines and antitank weapons. Tracked AFVs can have as many as nine road wheels on each side. Many wheeled AFVs have six or eight wheels, to help them ride over rough and soft ground.

The earliest tanks of the Great War had fixed suspensions—with no movement whatsoever. This unsatisfactory situation was improved with leaf spring suspensions adopted from agricultural machinery, but even these had very limited travel.

Speeds increased due to more powerful engines, and the quality of ride had to be improved. In the 1930s, the Christie suspension was developed, which allowed the use of coil springs inside a vehicle's armoured hull, by redirecting the direction of travel using a bell crank. Horstmann suspension was a variation which used a combination of bell crank and exterior coil springs, in use from the 1930s to the 1990s.

By the Second World War the other common type was torsion-bar suspension, getting spring force from twisting bars inside the hull—this had less travel than the Christie type, but was significantly more compact.

Torsion bar suspensions have been the dominant heavy armored vehicle suspension since the Second World War, sometimes but not always including shock absorbers.

Dashpot

A dashpot is a mechanical device, a damper which resists motion via viscous friction. The resulting force is proportional to the velocity, but acts in the opposite direction, slowing the motion and absorbing energy. It is commonly used in conjunction with a spring (which acts to resist displacement). The diagram symbol for a dashpot is pictured at right.

Types

Two common types of dashpots exist - linear and rotary. Linear dashpots are generally specified by stroke (amount of linear displacement) and damping coefficient (force per velocity). Rotary dashpots will have damping coeffients in torque per angular velocity.

A less common type of dashpot is an eddy current damper, which uses a large magnet inside of a tube constructed out of a non-magnetic but conducting material (such as aluminum or 316 stainless steel). Like a common viscous damper, the eddy current damper produces a resistive force proportional to velocity.

Applications

dashpot in a Stromberg carburetor

A dashpot is a common component in a door closer to prevent it from slamming shut. A spring applies force to close the door and the dashpot, implemented by requiring fluid to flow through a narrow channel between reservoirs (often with a size adjustable by a screw), slows down the motion of the door.

Dashpots are commonly used in dampers and shock absorbers. The hydraulic cylinder in an automobile shock absorber is a dashpot.

RLC circuit An RLC circuit (also known as a resonant circuit or a tuned circuit) is an electrical circuit consisting of a resistor (R), an inductor (L), and a capacitor (C), connected in series or in parallel.

Tuned circuits have many applications particularly for oscillating circuits and in radio and communication engineering. They can be used to select a certain narrow range of frequencies from the total spectrum of ambient radio waves. For example, AM/FM radios with analog tuners typically use an RLC circuit to tune a radio frequency. Most commonly a variable capacitor is attached to the tuning knob, which allows you to change the value of C in the circuit and tune to stations on different frequencies.

An RLC circuit is called a second-order circuit as any voltage or current in the circuit can be described by a second-order differential equation for circuit analysis.

Configurations

Every RLC circuit consists of two components: a power source and resonator. There are two types of power sources – Thévenin and Norton. Likewise, there are two types of resonators – series LC and parallel LC. As a result, there are four configurations of RLC circuits:

• Series LC with Thévenin power source • Series LC with Norton power source • Parallel LC with Thévenin power source • Parallel LC with Norton power source.

Similarities and differences between series and parallel circuits

The expressions for the bandwidth in the series and parallel configuration are inverses of each other. This is particularly useful for determining whether a series or parallel configuration is to be used for a particular circuit design. However, in circuit analysis, usually the reciprocal of the latter two variables are used to characterize the system instead. They are known as the resonant frequency and the Q factor respectively.

Fundamental Parameters

There are two fundamental parameters that describe the behavior of RLC circuits: the resonant frequency and the damping factor. In addition, other parameters derived from these first two are discussed below.

Resonant frequency

The undamped resonance or natural frequency of an RLC circuit (in radians per second) is:

In the more familiar unit hertz, the natural frequency becomes

Resonance occurs when the complex impedance ZLC of the LC resonator becomes zero:

ZLC = ZL + ZC = 0

Both of these impedances are functions of complex angular frequency s:

ZL = Ls

Setting these expressions equal to one another and solving for s, we find:

where the resonance frequency ωo is given in the expression above.

Damping factor

The damping factor of the circuit (in radians per second) is:

For applications in oscillator circuits, it is generally desirable to make the damping factor as small as possible, or equivalently, to increase the quality factor (Q) as much as possible. In practice, this requires decreasing the resistance R in the circuit to as small as physically possible. In this case, the RLC circuit becomes a good approximation to an ideal LC circuit, which is not realizable in practice. (Even if the resistor is removed from the circuit, there is always a small but non-zero amount of resistance in the wiring and interconnects between the other circuit elements that can never be eliminated entirely).

Alternatively, for applications in bandpass filters, the value of the damping factor is chosen based on the desired bandwidth of the filter. For a wider bandwidth, a larger value of the damping factor is required (and vice versa). In practice, this requires adjusting the relative values of the resistor R and the inductor L in the circuit.

Derived Parameters

The derived parameters include Bandwidth, Q factor, and damped resonance frequency.

Bandwidth

The RLC circuit may be used as a bandpass or band-stop filter, and the bandwidth (in radians per second) is

Alternatively, the bandwidth in hertz is

The bandwidth is a measure of the width of the frequency response at the two half-power frequencies. As a result, this measure of bandwidth is sometimes called the full-width at

half-power. Since electrical power is proportional to the square of the circuit voltage (or

current), the frequency response will drop to at the half-power frequencies.

Quality or Q factor

The Quality of the series tuned circuit, or Q factor, is calculated as the ratio of the resonance frequency ωo to the bandwidth ∆ω (in radians per second):

Or in hertz:

For the parallel tuned circuit:

Q is a dimensionless quantity.

Resonance Damping

The damped resonance frequency derives from the natural frequency and the damping factor. If the circuit is underdamped, meaning

then we can define the damped resonance as

In an oscillator circuit

.

As a result

(approx).

See discussion of underdamping, overdamping, and critical damping, below.

Circuit Analysis

Series RLC with Thévenin power source

In this circuit, the three components are all in series with the voltage source.

Series RLC Circuit notations:

v - the voltage of the power source (measured in volts V) i - the current in the circuit (measured in amperes A) R - the resistance of the resistor (measured in ohms = V/A); L - the inductance of the inductor (measured in henries = H = V·s/A) C - the capacitance of the capacitor (measured in farads = F = C/V = A·s/V)

Given the parameters v, R, L, and C, the solution for the current i using Kirchhoff's voltage law (KVL) is:

For a time-changing voltage v(t), this becomes

Rearranging the equation gives the following second order differential equation:

We now define two key parameters:

and

both of which are measured as radians per second.

Substituting these parameters into the differential equation, we obtain:

or

The Zero Input Response (ZIR) solution

Setting the input (voltage sources) to zero, we have:

with the initial conditions for the inductor current, iL(0), and the capacitor voltage, vC(0). In order to solve the equation properly, the initial conditions needed are i(0) and i'(0).

The first one we already have since the current in the main branch is also the current in the inductor, therefore

The second one is obtained employing KVL again:

So

and

We have now a homogeneous second order differential equation with two initial conditions. Substituting the two parameters ζ and ω0, we have

We now form the equation’s characteristic polynomial

Using the quadratic formula, we find the roots as

Depending on the values of ζ and ω0, there are three possible cases:

Over-damping

RLC series Over-Damped Response

In this case, the characteristic polynomial's solutions are both negative real numbers.

Two negative real roots, the solutions are:

This is called "over-damping".

Critical damping

RLC series Critically Damped

In this case, the characteristic polynomial's solutions are identical negative real numbers.

The two roots are identical (λ1 = λ2 = λ), the solutions are:

I(t) = (A + Bt)eλt for arbitrary constants A and B

This is called "critical damping".

Under-damping

RLC series Under-Damped

In this case, the characteristic polynomial's solutions are complex conjugate and have negative real parts. The solution consists of two conjugate roots

λ1 = − ζ + iωc

and

λ2 = − ζ − iωc

where

The solutions are:

for arbitrary constants A and B.

Using Euler's formula, we can simplify the solution to

for arbitrary constants C and D.

This is called "under-damping" and results in oscillations or ringing in the circuit.

These solutions are characterized by exponentially decaying sinusoidal response. The time required for the oscillations to "die out" depends on the Quality of the circuit, or Q factor. The higher the Quality, the longer it takes for the oscillations to decay. As before, for a series RLC circuit,

which is a dimensionless parameter.

The Zero State Response (ZSR) solution

This time we set the initial conditions to zero and have:

with the initial condition

i(0 − ) = i'(0 − ) = 0

There are two approaches we can take to finding the ZSR: (1) the Laplace transform, and (2) the convolution integral.

Laplace Transform

We first take the Laplace transform of the second order differential equation:

or

where v(s) is the Laplace transform of the input signal:

We then solve for the complex admittance Y(s) (in siemens):

We can then use the admittance Y(s) and the Laplace transform of the input voltage v(s) to find the complex electrical current i(s):

I(s) = Y(s)v(s)

Finally, we can find the electrical current in the time domain by taking the inverse Laplace transform:

Example:

Suppose v(t) = Au(t)

where u(t) is the Heaviside step function.

Then

Convolution Integral

A single closed solution for every possible function for v(t) is impossible. However, there is a way to find a formula for i(t) using convolution. In order to do that, we need a solution for a basic input, the Dirac delta function.

To find the solution more easily we will start solving for the Heaviside step function and then use the fact that our circuit is a linear system, so its derivative will be the solution for the delta function.

The equation will be therefore, for t>0:

Assuming λ1 and λ2 are the roots of

then as in the ZIR solution, we have 3 cases here:

Over-damping

Two negative real roots. The solution is:

Critical damping

The two roots are identical (λ1 = λ2 = λ), the solution is:

Under-damping

Two conjugate roots ( ), the solution is:

(to be continued...)

Frequency Domain

The series RLC can be analyzed in the frequency domain using complex impedance relations. If the voltage source above produces a complex exponential wave form with amplitude v(s) and angular frequency s = σ + iω , KVL can be applied:

where i(s) is the complex current through all components. Solving for i:

And rearranging, we have

Complex Admittance

Next, we solve for the complex admittance Y(s):

Finally, we simplify using parameters α and ωo

Notice that this expression for Y(s) is the same as the one we found for the Zero State Response.

Poles and Zeros

The zeros of Y(s) are those values of s such that Y(s) = 0:

s = 0 and

The poles of Y(s) are those values of s such that :

Notice that the poles of Y(s) are identical to the roots λ1 and λ2 of the characteristic polynomial.

Sinusoidal Steady State

If we now let s = iω....

Taking the magnitude of the above equation:

Next, we find the magnitude of current as a function of ω

| I(iω) | = | Y(iω) | | V(iω) |

If we choose values where R = 1 ohm, C = 1 farad, L = 1 henry, and V = 1.0 volt, then the graph of magnitude of the current i (in amperes) as a function of ω (in radians per second) is:

Sinusoidal steady-state analysis

Note that there is a peak at imag(ω) = 1. This is known as the resonant frequency. Solving for this value, we find:

Parallel RLC circuit

A much more elegant way of recovering the circuit properties of an RLC circuit is through the use of nondimensionalization.

Parallel RLC Circuit notations:

V - the voltage of the power source (measured in volts V) I - the current in the circuit (measured in amperes A) R - the resistance of the resistor (measured in

ohms = V/A); L - the inductance of the inductor (measured in henries = H = V·s/A) C - the capacitance of the capacitor (measured in farads = F = C/V = A·s/V)

For a parallel configuration of the same components, where Φ is the magnetic flux in the system

with substitutions

The first variable corresponds to the maximum magnetic flux stored in the circuit. The second corresponds to the period of resonant oscillations in the circuit.

Shock absorber

Gasfilled Shock absorber.

A shock absorber in common parlance (or damper in technical use) is a mechanical device designed to smooth out or damp a sudden shock impulse and dissipate kinetic energy. It is analogous to a resistor in an electric RLC circuit.

Explanation

Shock absorbers must absorb or dissipate energy. One design consideration, when designing or choosing a shock absorber is where that energy will go. In most dashpots, energy is converted to heat inside the viscous fluid. In hydraulic cylinders, the hydraulic fluid will heat up. In air cylinders, the hot air is usually exhausted to the atmosphere. In other types of dashpots, such as electromagnetic ones, the dissipated energy can be stored and used later.

Description

Pneumatic and hydraulic shock absorbers commonly take the form of a cylinder with a sliding piston inside. The cylinder is filled with a fluid, such as hydraulic fluid or air. This fluid filled piston/cylinder combination is a dashpot.

Applications

Shock absorbers are an important part of automobile suspensions, aircraft landing gear, and the supports for many industrial machines. Large shock absorbers have also been used in architecture and civil engineering to reduce the susceptibility of structures to earthquake damage and resonance.

Vehicles suspension

In a vehicle, it reduces the effect of travelling over rough ground. Without shock absorbers, the vehicle would have a bouncing ride, as energy is stored in the spring and then released to the vehicle, possibly exceeding the allowed range of suspension movement. Control of excessive suspension movement without shock absorption requires stiffer (higher rate) springs, which would in turn give a harsh ride. Shock absorbers allow the use of soft (lower rate) springs while controlling the rate of suspension movement in response to bumps. They also, along with hysteresis in the tire itself, damp the motion of the unsprung weight up and down on the springiness of the tire. Since the tire is not as soft as the springs, effective wheel bounce damping may require stiffer shocks than would be ideal for the vehicle motion alone.

Spring-based shock absorbers commonly use coil springs or leaf springs, though torsion bars can be used in torsional shocks as well. Ideal springs alone, however, are not shock absorbers as springs only store and do not dissipate or absorb energy. Vehicles typically employ both springs or torsion bars as well as hydraulic shock absorbers. In this combination, "shock absorber" is reserved specifically for the hydraulic piston that absorbs and dissipates vibration.

Structures

Applied to a structure such as a building or bridge it may be part of a seismic retrofit or as part of new, earthquake resistant construction. In this application it allows yet restrains motion and absorbs resonant energy, which can cause excessive motion and eventual structural failure.

Types of shock absorbers

There are several commonly-used approaches to shock absorption:

• Hysteresis of structural material, for example the compression of rubber disks, stretching of rubber bands and cords, bending of steel springs, or twisting of torsion bars. Hysteresis is the tendency for otherwise elastic materials to rebound with less force than was required to deform them. Simple vehicles with no separate shock absorbers are damped, to some extent, by the hysteresis of their springs and frames.

• Dry friction as used in wheel brakes, but using disks (classically made of leather) at the pivot of a lever, with friction forced by springs. Used in early automobiles such as the Ford Model T, up through some British cars of the 1940s. Although now considered obsolete, an advantage of this system is its mechanical simplicity; the degree of damping can be easily adjusted by tightening or loosening the screw clamping the disks, and it can be easily rebuilt with simple hand tools. A disadvantage is that the damping force tends not to increase with the speed of the vertical motion.

• Fluid friction, for example the flow of fluid through a narrow orifice (hydraulics), constitute the vast majority of automotive shock absorbers. An advantage of this type is that using special internal valving the absorber may be made relatively soft to compression (allowing a soft response to a bump) and relatively stiff to extension, controlling "jounce", which is the vehicle response to energy stored in the springs; similarly, a series of valves controlled by springs can change the degree of stiffness according to the velocity of the impact or rebound. Specialized shock absorbers for racing purposes may allow the front end of a dragster to rise with minimal resistance under acceleration, then strongly resist letting it settle, thereby maintaining a desirable rearward weight distribution for enhanced traction. Some shock absorbers allow tuning of the ride via control of the valve by a manual adjustment provided at the shock absorber. In more expensive vehicles the valves may be remotely adjustable, offering the driver control of the ride at will while the vehicle is operated. The ultimate control is provided by dynamic valve control via computer in response to sensors, giving both a smooth ride and a firm suspension when needed. Many shock absorbers contain compressed

nitrogen, to reduce the tendency for the oil to foam under heavy use. Foaming temporarily reduces the damping ability of the unit. In very heavy duty units used for racing and/or off-road use, there may even be a secondary cylinder connected to the shock absorber to act as a reservoir for the oil and pressurized gas.

• Compression of a gas, for example pneumatic shock absorbers, which can act like springs as the air pressure is building to resist the force on it. Once the air pressure reaches the necessary maximum, air dashpots will act like hydraulic dashpots. In aircraft landing gear air dashpots may be combined with hydraulic dampening to reduce bounce. Such struts are called "oleo" struts (combining oil and air) .

• Magnetic effects. Eddy current dampers are dashpots that are constructed out of a large magnet inside of a non-magnetic, eclectically conductive tube. Furthermore, many modern hybrid automobiles have regenerative braking, which uses a reversed electric motor to dampen and eventually stop the motion of the car.

• Inertial resistance to acceleration, for example the Citroën 2CV has an additional pair of rear shock absorbers that damp wheel bounce with no external moving parts. The energy is absorbed by hydraulic fluid friction, but their operation depends on the inertia of an internal weight. These are essentially small versions of the tuned mass dampers used on tall buildings

• Composite hydropneumatic devices which combine in a single device spring action, shock absorption, and often also ride-height control, as in some models of the Citroën automobile.

• Conventional shock absorbers combined with composite pneumatic springs with which allow ride height adjustment or even ride height control, seen in some large trucks and luxury sedans such as certain Lincoln automobiles. Ride height control is especially desirable in highway vehicles intended for occasional rough road use, as a means of improving handling and reducing aerodynamic drag by lowering the vehicle when operating on improved high speed roads.

• The effect of a shock absorber at high (sound) frequencies is usually limited by using a compressible gas as the working fluid and/or mounting it with rubber bushings.

Multi-link suspension

Multi-link rear suspension of the 5-link type (rear view above, top view below)

A multi-link suspension is a type of vehicle suspension design typically used in independent suspensions, using three or more lateral arms, and one or more longitudinal arms. These arms do not have to be of equal length, and may be angled away from their 'obvious' direction.

Typically each arm has a spherical joint (ball joint) or rubber bushing at each end. Consequently they react loads along their own length, in tension and compression, but not in bending. Some multi-links do use a swing arm or wishbone, which has two bushings at one end.

On a front suspension one of the lateral arms is replaced by the tie-rod, which connects the rack or steering box to the wheel hub.

In order to simplify understanding it is usual to consider the function of the arms in each of three orthogonal planes.

Plan view

The arms have to control toe/steer and lateral compliance. This needs a pair of arms longitudinally separated.

Front view

The arms have to control camber, particularly the way that the camber changes as the wheel moves up (into jounce, or bump) and down into rebound or droop.

Side view

The arms have to react traction and braking loads, usually accomplished via a longitudinal link. They also have to control caster. Note that brake torques also have to be reacted - either by a second longitudinal link, or by rotating the hub, which forces the lateral arms out of plane, so allowing them to react 'spin' forces, or by rigidly fixing the longitudinal link to the hub.

Advantages of multi-link suspension

In its simplest form the multi-link suspension is orthogonal - that is, it is possible to alter one parameter in the suspension at a time, without affecting anything else.

This is in direct contrast to say a double wishbone suspension where moving a hardpoint or changing a bushing compliance will affect two or more parameters.

Advantages also extend to off road driving. A multi-link suspension will allow the vehicle to flex more, this means simply that the suspension will be able to move more easily to conform to the varying angles of off roading. This being said, multi-link equipped vehicles are ideally suited for sports such as rock crawling, and desert racing. A side note to the use of multi-link suspension use in desert racing, the use of a good sway bar is needed to counter body roll.

Disadvantages of multi-link suspension

It is difficult to tune the geometry without a full 3D analysis. Compliance under load can have an important effect and must be checked using a multibody simulation software

Trailing arm A trailing-arm suspension is an automobile suspension design in which one or more arms (or "links") are connected between (and perpendicular to) the axle and the chassis. Simple trailing-arm designs in live axle setups often use just two or three links and a Panhard rod to locate the wheel laterally.

A semi-trailing arm suspension is an independent rear suspension system for automobiles in which each wheel hub is located only by a large, roughly triangular arm that pivots at two points. Viewed from the top, the line formed by the two pivots is somewhere between parallel and perpendicular to the car's longitudinal axis; it is generally parallel to the ground.

Trailing-arm and multilink suspension designs are much more commonly used for the rear wheels of a vehicle where they can allow for a flatter floor and more cargo room. Many small vehicles feature a MacPherson strut front suspension and trailing-arm rear axle.

Car handling Car handling and vehicle handling is a description of the way wheeled vehicles perform transverse to their direction of motion, particularly during cornering and swerving. It also includes their stability when moving in a straight line. Handling and braking are the major components of a vehicle's "active" safety. The maximum lateral acceleration is sometimes discussed separately as "road holding". Handling is an esoteric performance area because rapid and violent manoeuvres are often only used in unforeseen circumstances. (This discussion is directed at road vehicles with at least three wheels, but some of it may apply to other ground vehicles.)

Cars, for use on public roads, whose engineering requirements emphasise handling above passenger space and comfort, are called sports cars.

Factors that affect a car's handling

Driver

Handling is a property of the car, but different characteristics will work well with different drivers.

Familiarity

A person learns to control a car much as he learns to control his body, so the more he has driven a car or type of car the better it will handle for him. One needs to take extra care for the first few thousand miles after buying a car, especially if it differs in design from those he is used to. Other things that a driver must adjust to include changes in tyres, tyre pressures and load. That is, handling is not just good or bad; it is also the same or different.

Weather

Weather affects handling by making the road slippery. Different tyres do best in different weather. Deep water is an exception to the rule that wider tyres improve road holding.

Road condition

Cars with relatively soft suspension and with low unsprung weight are least affected by uneven surfaces, while on flat smooth surfaces the stiffer the better. Unexpected water, ice, oil, etc. are hazards.

Weight distribution

Center of gravity height

The center (centre) of gravity height, relative to the track, determines load transfer, also called weight transfer, from side to side and causes body lean. Centrifugal force acts at the center of gravity to lean the car toward the outside of the curve, increasing downward force on the outside tyres.

The centre of gravity height, relative to the wheelbase, determines load transfer between front and rear. The car's momentum acts at its center of gravity to twist the car forward or backward, respectively during braking and acceleration. Since it is only the downward force that changes and not the location of the center of gravity, the effect on over/under steer is opposite to that of an actual change in the center of gravity. When a car is braking, the downward load on the front tyres increases and that on the rear decreases, with corresponding change in their ability to take sideways load, causing oversteer.

Lower center of gravity is the principle performance advantage of sports cars, compared to sedans and (especially) SUVs. Some cars have light materials in their roofs, partly for this reason. It is also part of the reason that traditional sports cars are open or convertible.

Body lean can also be controlled by the springs, anti-roll bars or the roll center heights.

Roll angular inertia

This increases the time it takes to settle down and follow the steering. It depends on the (square of) the height and width, and (for a uniform mass distribution) can be approximately calculated by the equation: I = M(height2 + width2) / 12-.

Greater width, then, though it counteracts centre of gravity height, hurts handling by increasing angular inertia. Some high performance cars have light materials in their fenders and roofs partly for this reason.

Center of gravity forward or back

In steady-state cornering, front heavy cars tend to understeer and rear heavy cars to oversteer, all other things being equal. This can be compensated, at least mostly, by using wheels and tyres with size (width times diameter) proportional to the weight carried by each end.

When all four wheels and tyres are of equal size, as is most often the case with passenger cars, a weight distribution close to "50/50" (i.e. the centre of mass is mid-way between the front and rear axles) produces the preferred handling compromise.

The rearward weight bias preferred by sports and racing cars results from handling effects during the transition from straight-ahead to cornering. During corner entry the front tyres, in addition to generating part of the lateral force required to accelerate the car's centre of mass into the turn, also generate a torque about the car's vertical axis that starts the car rotating into the turn. However, the lateral force being generated by the rear tyres is acting in the opposite torsional sense, trying to rotate the car out of the turn. For this reason, a car with "50/50" weight distribution will understeer on initial corner entry. To avoid this problem, sports and racing cars often have a more rearward weight distribution. In the case of pure racing cars, this is typically between "45/55" and "40/60." This gives the front tyres an advantage in overcoming the car's moment of inertia (yaw angular inertia), thus reducing corner-entry understeer.

Once a car is designed, weight distribution can be changed by using different diameter tyres or jacking the car up higher or lower at the suspension springs. Jacking is frequently done with screws or shims at the springs.

Yaw and pitch angular inertia (polar moment)

Unless the vehicle is very short, compared to its height or width, these are about equal. Angular inertia determines the rotational inertia of an object for a given rate of rotation. The yaw angular inertia tends to keep the direction the car is pointing changing at a constant rate. This makes it slower to swerve or go into a tight curve, and it also makes it slower to turn straight again. The pitch angular inertia detracts from the ability of the suspension to keep front and back tyre loadings constant on uneven surfaces and therefore contributes to bump steer. Angular inertia is an integral over the square of the distance from the centre of gravity, so it favors small cars even though the lever arms (wheelbase and track) also increase with scale. (Since cars have reasonable symmetrical shapes, the off-diagonal terms of the angular inertia tensor can usually be ignored.) Mass

near the ends of a car can be avoided, without re-designing it to be shorter, by the use of light materials for bumpers and fenders or by deleting them entirely.

Suspension

Automobile suspensions have many variable characteristics, which are generally different in the front and rear and all of which affect handling. Some of these are: spring rate, damping, straight ahead camber angle, camber change with wheel travel, roll centre height and the flexibility and vibration modes of the suspension elements. Suspension also affects unsprung weight.

Many cars have suspension that connects the wheels on the two sides, either by a sway bar and/or by a solid axle. The Citroën 2CV has interaction between the front and rear suspension.

The flexing of the frame interacts with the suspension. (See below.)

Tyres and wheels

In general, larger tyres, softer rubber, higher hysteresis rubber and stiffer cord configurations increase road holding and improve handling. On most types of poor surfaces, large diameter wheels perform better than lower wider wheels. The fact that larger tyres, relative to weight, stick better is the main reason that front heavy cars tend to understeer and rear heavy to oversteer. The depth of tread remaining greatly affects aquaplaning (riding over deep water without reaching the road surface). Increasing tyre pressures reduces their slip angle, but (for given road conditions and loading) there is an optimum pressure for road holding.

Track and wheelbase

The track provides the resistance to sideways weight transfer and body lean. The wheelbase provides resistance to front/back weight transfer and to pitch angular inertia, and provides the torque lever arm to rotate the car when swerving. The wheelbase, however, is less important than angular inertia (polar moment) to the vehicle's ability to swerve quickly.

Unsprung weight

Ignoring the flexing of other components, a car can be modelled as the sprung weight, carried by the springs, carried by the unsprung weight, carried by the tyres, carried by the road. Without the unsprung weight, the force of a tyre on the road would come from the vehicle weight and motion, transmitted by the spring. But the unsprung weight is cushioned from uneven road surfaces only by the springiness of the tyres (and wire wheels if fitted). To aggravate this (for fuel economy and to avoid overheating at high speed) tyres have limited internal damping. So the "wheel bounce" or resonant motion of the unsprung weight moving up and down on the springiness of the tyre is only poorly damped, mainly by the dampers or Shock absorbers of the suspension. For these reasons, high unsprung weight reduces road holding and increases unpredictable changes in direction on rough surfaces (as well as degrading ride comfort and increasing mechanical loads).

This unsprung weight includes the wheels and tyres, usually the brakes, plus some percentage of the suspension, depending on how much of the suspension moves with the body and how much with the wheels; for instance a solid axle is completely unsprung. The main factors that improve unsprung weight are a sprung differential (as opposed to live axle) and inboard brakes. (The De Dion tube suspension operates much as a live axle does, but represents an improvement because it is lighter, thereby reducing the unsprung weight.) Aluminium wheels also help. Magnesium wheels are even lighter but corrode easily.

Since only the brakes on the driving wheels can easily be inboard, the Citroën 2CV had additional dampers on its rear wheel hubs to damp only wheel bounce.

Aerodynamics

Aerodynamic forces are generally proportional to the square of the air speed, therefore car aerodynamics become rapidly more important as speed increases. Like darts, aeroplanes, etc., cars can be stabilised by fins and other rear aerodynamic devices. However, in addition to this cars also use downforce or "negative lift" to improve road holding. This is prominent on many types of racing cars, but is also used on most passenger cars to some degree, if only to counteract the tendency for the car to otherwise produce positive lift.

In addition to providing increased adhesion, car aerodynamics are frequently designed to compensate for the inherent increase in oversteer as cornering speed increases. When a car corners, it must rotate about its vertical axis as well as translate its centre of mass in an arch. However, in a tight-radius (lower speed) corner the angular velocity of the car is high, while in a longer-radius (higher speed) corner the angular velocity is much lower. Therefore, the front tyres have a more difficult time overcoming the car's moment of inertia during corner entry at low speed, and much less difficulty as the cornering speed increases. So the natural tendency of any car is to understeer on entry to low-speed corners and oversteer on entry to high-speed corners. To compensate for this unavoidable effect, car designers often bias the car's handling toward less corner-entry understeer (such as by lowering the front roll center), and add rearward bias to the aerodynamic downforce to compensate in higher-speed corners. The rearward aerodynamic bias may be achieved by an airfoil or "spoiler" mounted near the rear of the car, but a useful effect can also be achieved by careful shaping of the body as a whole, particularly the aft areas

Delivery of power to the wheels and brakes

The coefficient of friction of rubber on the road limits the magnitude of the vector sum of the transverse and longitudinal force. So the driven wheels or those supplying the most braking tend to slip sideways. This phenomenon is often explained by use of the circle of forces model.

One reason that sports cars are usually rear wheel drive is that power induced oversteer is useful, to a skilled driver, for tight curves. The weight transfer under acceleration has the opposite effect and either may dominate, depending on the conditions. Inducing understeer by applying power in a front wheel drive car is less useful. In any case, this is not an important safety issue, because power is not normally used in emergency situations. Using low gears down steep hills may cause some oversteer.

The effect of braking on handling is complicated by load transfer, which is proportional to the (negative) acceleration times the ratio of the centre of gravity height to the wheelbase. The difficulty is that the acceleration at the limit of adhesion depends on the road surface, so with the same ratio of front to back braking force, a car will understeer under braking on slick surfaces and oversteer under hard braking on solid surfaces. Most modern cars combat this by varying the distribution of braking in some way. This is important with a high centre of gravity, but it is also done on low centre of gravity cars, from which a higher level of performance is expected.

Position and support for the driver

Having to take up "g forces" in his/her arms interferes with a driver's precise steering. In a similar manner, a lack of support for the seating position of the driver may cause them to move around as the car undergoes rapid acceleration (through cornering, taking off or braking). This interferes with precise control inputs, making the car more difficult to control.

Being able to reach the controls easily is also an important consideration, especially if a car is being driven hard.

In some circumstances, good support may allow a driver to retain some control, even after a minor accident or after the first stage of an accident.

Steering

Depending on the driver, steering force and transmission of road forces back to the steering wheel and the steering ratio of turns of the steering wheel to tuns of the road wheels affect control and awareness. Play — free rotation of the steering wheel before the wheels rotate — is a common problem, especially in older model and worn cars. Another is friction. Rack and pinion steering is generally considered the best type of mechanism for control effectiveness. The linkage also contributes play and friction. Caster — offset of the steering axis from the contact patch — provides some of the self centring tendency.

Precision of the steering is particularly important on ice or hard packed snow where the slip angle at the limit of adhesion is smaller than on dry roads.

The steering effort depends on the downward force on the steering tyres and on the radius of the contact patch. So for constant tyre pressure, it goes like the 1.5 power of the vehicle's weight. The driver's ability to exert torque on the wheel scales similarly with her size. The wheels must be rotated farther on a longer car to turn with a given radius. Power steering reduces the required force at the expense of feel. It is useful, mostly in parking, when the weight of a front-heavy vehicle exceeds about ten or fifteen times the driver's weight, for physically impaired drivers and when there is much friction in the steering mechanism.

Four-wheel steering has begun to be used on road cars (Some WW II reconnaissance vehicles had it). It relieves the effect of angular inertia by starting the whole car moving before it rotates toward the desired direction. It can also be used, in the other direction, to reduce the turning radius. Some cars will do one or the other, depending on the speed.

Steering geometry changes due to bumps in the road may cause the front wheels to steer in a different directions together or independent of each other. The steering linkage should be designed to minimise this effect.

Suspension travel

The severe handling vice of the TR3 and related cars was caused by running out of suspension travel. (See below.) Other vehicles will run out of suspension travel with some combination of bumps and turns, with similarly catastrophic effect. Excessively modified cars also may encounter this problem.

Electronic stability control

Since automobile safety is mainly a control issue, one should expect a largely electronic solution. Apparently there has already been some advance in this direction.

On the other hand, since stability control works by reducing sudden manoeuvres, until the electronics helps to detect the danger sooner, it can never take the place of a low centre of gravity, which provides both stability and fast avoidance. (See Wireless vehicle safety communications.)

The stability control of some cars may not be compatible with some driving techniques, such as power induced over-steer. It is therefore, at least from a sporting point of view, preferable that it can be disabled.

Alignment of the wheels

Of course things should be the same, left and right. Camber affects steering because a tyre tends to move in the direction the top of it is leaning.

Rigidity of the frame

The frame may flex with load, especially twisting on bumps. Rigidity is considered to help handling. At least it simplifies the suspension engineers work. Some cars, such as the Mercedes-Benz 300SL have had high doors to allow a stiffer frame.

Common handling problems

When any wheel leaves contact with the road there is a change in handling, so the suspension should keep all four (or three) wheels on the road in spite of hard cornering, swerving and bumps in the road. It is very important for handling, as well as other reasons, not to run out of suspension travel and "bottom" or "top".

It is usually most desirable to have the car adjusted for neutral steer, so that it responds predictably to a turn of the steering wheel and the rear wheels have the same slip angle as the front wheels. However this may not be achievable for all loading, road and weather conditions, speed ranges, or while turning under acceleration or braking. Ideally, a car should carry passengers and baggage near its centre of gravity and have similar tyre loading, camber angle and roll stiffness in front and back to minimise the variation in handling characteristics. A driver can learn to deal with oversteer or understeer, but not if it varies greatly.

The most important common handling failings are;

• Understeer - the front wheels tend to crawl slightly or even slip and drift towards the outside of the turn. The driver can compensate by turning a little more tightly, but road-holding is reduced, the car's behaviour is less predictable and the tyres are liable to wear more quickly.

• Oversteer - the rear wheels tend to crawl or slip towards the outside of the turn more than the front. The driver must correct by steering away from the corner, otherwise the car is liable to spin, if pushed to its limit. Oversteer is sometimes useful, to assist in steering, especially if it occurs only when the driver chooses it by applying power.

• Bump steer – Is the effect of irregularity of a road surface on the angle or motion of a car. It may be the result of the kinematic motion of the suspension rising or falling, causing tow-in or toe-out at the loaded wheel, ultimately affecting the yaw angle (heading) of the car. This will always happen under some conditions but depends on suspension, steering linkage, unsprung weight, angular inertia, differential type, frame rigidity, tyres and tyre pressures. If suspension travel is exhausted the wheel either bottoms or loses contact with the road. As with hard turning on flat roads, it is better if the wheel picks up by the spring reaching its neutral shape, rather than by suddenly contacting a limiting structure of the suspension.

• Body roll - the car leans towards the outside of the curve. This interferes with the driver's control, because he must wait for the car to finish leaning before he can fully judge the effect of his steering change. It also adds to the delay before the car moves in the desired direction.

• Weight transfer - the wheels on the outside of a curve are more heavily loaded than those on the inside. This tends to overload the tyres on the outside and therefore reduce road holding. Weight transfer (sum of front and back), in steady cornering, is determined by the ratio of the height of a car's centre of gravity to its track. Differences between the weight transfer in front and back are determined by the relative roll stiffness and contribute to the over or under-steer characteristics.

o When the weight transfer equals half the vehicle's loaded weight, it will start to roll over. This can be avoided by manually or automatically reducing the turn rate, but this causes further reduction in road-holding. (A collision may be preferable to a rollover.)

• Slow response - sideways acceleration does not start immediately when the steering is turned and may not stop immediately when it is returned to centre. This

is partly caused by body roll. Other causes include tyres with high slip angle, and yaw and roll angular inertia. Roll angular inertia aggravates body roll by delaying it. Soft tyres aggravate yaw angular inertia by waiting for the car to reach their slip angle before turning the car.

Compromises

For ordinary production cars, manufactures err towards deliberate understeer as this is safer for inexperienced or inattentive drivers than is oversteer. Other compromises involve comfort and utility, such as preference for a softer smoother ride or more seating capacity. High levels of comfort are incompatible with a low centre of gravity, body roll resistance, low angular inertia, support for the driver, steering feel and other characteristics that make a car handle well. Inboard brakes improve both handling and comfort but take up space and are harder to cool. Large engines, tend to make cars front or rear heavy. In tyres, fuel economy, staying cool at high speeds, ride comfort and long wear all tend to conflict with road holding, while wet, dry, deep water and snow road holding are not exactly compatible. A-arm or wishbone front suspension tends to give better handling, because it provides the engineers more freedom to choose the geometry, and more road holding, because the camber is better suited to radial tyres, than MacPherson strut, but it takes more space. Live solid axle rear suspension is mainly used to reduce cost, but, in general, cost is a relatively less important factor.

In fact, cost may sometimes be negatively correlated with handling, because small size, though it makes little difference in the cost of the car itself, improves both handling and fuel economy (as well as braking, parking, etc.). This may have been true in the US in the late 1950s when many of the European imports undersold the Detroit "dinosaurs". It may again be true in the 2000s, now that large cars, called SUVs or styled as pickups, have regained popularity.

Aftermarket modifications and adjustments to affect handling

Component Reduce Under-steer Reduce Over-steer

Weight distribution centre of gravity towards centre of gravity towards

rear front

Front shock absorber softer stiffer

Rear shock absorber stiffer softer

Front sway bar softer stiffer

Rear sway bar stiffer softer

Front tyre selection1 larger contact area2 smaller contact area

Rear tyre selection smaller contact area larger contact area2

Front wheel rim width or diameter larger2 smaller

Rear wheel rim width or diameter smaller larger2

Front tyre pressure higher pressure lower pressure

Rear tyre pressure lower pressure higher pressure

Front wheel camber increase negative camber reduce negative camber

Rear wheel camber reduce negative camber increase negative camber

Rear spoiler smaller larger

Front height (because these usually affect camber and roll resistance)

lower front end raise front end

Rear height raise rear end lower rear end

Front toe in increase decrease

Rear toe in decrease increase

1) tyre contact area can be increased by using wider tyres, or tyres with fewer grooves in the tread pattern. Of course fewer grooves has the opposite effect in wet weather or other poor road conditions.

2) These also improve road holding, under most conditions.

In addition, lowering the centre of gravity will always help the handling (as well as reduce the chance of roll-over). This can be done to some extent by using plastic windows (or none) and light roof, hood (bonnet) and boot (trunk) lid materials, by reducing the ground clearance, etc. Increasing the track with "reversed" wheels will have a similar effect, but remember that the wider the car the less spare room it has on the road

and the farther you may have to swerve to miss an obstacle. Stiffer springs and/or shocks, both front and rear, will generally improve handling, at the expense of comfort on small bumps. Performance suspension kits are available. Light alloy (mostly aluminium or magnesium) wheels improve handling and ride as well as appearance.

Moment of inertia can be reduced by using lighter bumpers and wings (fenders), or none at all.

Cars with unusual handling problems

• early Porsche 911s — the inside front wheel leaves the road during hard cornering on dry pavement. This causes increasing understeer, but it is still considered to have acceptable handling, even for a sports car. The roll bar stiffness at the front is set to compensate for the rear-heaviness and gives neutral handling in ordinary driving. This compensation starts to give out when the wheel lifts. A skilled driver can use the 911's other features to his/her advantage, making the 911 an extremely capable sports car. Later 911s have had increasingly sophisticated rear suspensions and larger rear tyres, eliminating these problems.

• Triumph TR2, TR3 and TR4 — began to oversteer more suddenly when their inside rear wheel lifted.

• Mercedes-Benz A-Class — early models showed excessive body roll during sharp swerving manoeuvres, most particularly during the Swedish moose test. This was later corrected using Electronic Stability Control and retrofitted at great expense to earlier cars.

• Volkswagen Beetle — (original Beetle) The limitations of the Beetle's handling and roll stability were blamed, by Ralph Nader, on the swing axle suspension. Since its design was based closely on Porsche's Auto Union grand prix car in the 1930s, it is surprising for many to hear that it was neither top heavy (as its appearance would suggest) nor particularly rear-heavy (in fact a well ballanced 42/58). Since they were produced for so long, with stickier tyres and more powerful engines, people who drove them hard fitted reversed wheels and bigger rear tyres and rims.

• The gaudy 1950s American "full size" "dinosaurs" — responded very slowly to steering changes, because of their very large angular inertia, soft but simple

suspension and comfort oriented cross bias tyres. Auto Motor und Sport reported on one of these that they lacked the courage to test it for top speed. Contact with Europe and the 1970s energy crisis have gradually relieved this problem. (Large trucks also cannot be made to respond quickly because of their angular inertia, and therefore usually licensing for their operation requires additional training.)

• When the American government in the early 1970s required new automobiles to withstand a five mile per hour impact without damage to any safety-related systems such as lighting, this was often accomplished by modifying existing designs so that the bumpers were heavier, mounted further out from the body (often on shock-absorbers), or both. This unavoidably increased the vehicles' moments of inertia for yaw and pitch.

• Dodge Omni and Plymouth Horizon — these early American responses to the Volkswagen Rabbit were found "Unacceptable" in their initial testing by Consumer Reports, due to an observed tendency to display an uncontrollable oscillating yaw from side to side under certain steering inputs. While Chrysler's denials of this behaviour were countered by a persistent trickle of independent reports of this behaviour, production of the cars was altered to equip them with both a lighter weight steering wheel and a steering damper, and no further reports of this problem were heard.

• The Suzuki Samurai — was similarly reported by Consumer Reports to exhibit a propensity to tipping over onto two wheels, to the point where they were afraid to continue testing the vehicle without the attachment of outrigger wheels to catch it from completely rolling over; once again, they rated it as "Unacceptable", and once again the manufacturer denied that it was any sort of problem "in the real world", while reports by owners who had experienced such rollovers steadily trickled in. The vehicle was eventually taken off the market before any changes were made to the handling. As SUVs became popular, however, it became evident that their high centre of mass made them more likely to tip over than passenger cars, and some even did so during Consumer Reports' testing; but none other than the Samurai showed such a readiness to roll over that they were rated unacceptable, as theoretically predictable by the Samurai's being exceptionally short and narrow.

• Ford SUVs — then were cited as having a dangerous tendency to blow a rear tyre and flip over. Ford and Firestone, the makers of the tyres, pointed fingers at each other, with the final blame being assigned to quality control practices at a Firestone plant which was undergoing a strike; it was widely surmised, however,

that at least part of the problem was caused by Ford specifying lower than optimum pressures in the tyres in order to induce them to lose traction and slide under sideways forces rather than to grip and force the vehicle to roll over. An internal document dated 1989 states

Engineering has recommended use of tyre pressures below maximum allowable inflation levels for all UN46 tyres. As described previously, the reduced tyre pressures increase understeer and reduce maximum cornering capacity (both 'stabilising' influences). This practice has been used routinely in heavy duty pick-up truck and car station wagon applications to assure adequate understeer under all loading conditions. Nissan (Pathfinder), Toyota, Chevrolet, and Dodge also reduce tyre pressures for selected applications. While we cannot be sure of their reasons, similarities in vehicle loading suggest that maintaining a minimal level of understeer under rear-loaded conditions may be the compelling factor. This contributed to build-up of heat and tyre deterioration under sustained high speed use, and eventual failure of the most highly stressed tyre. Of course, the possibility that slightly substandard tyre construction and slightly higher than average tyre stress, neither of which would be problematic in themselves, would in combination result in tyre failure is quite likely. The controversy continues without unequivocal conclusions, but it also brought public attention to a generally high incidence of rollover accidents involving SUVs, which the manufacturers continue to address in various ways.

(One of the handling advantages of sports cars is that their very lack of carrying capacity allows their standard tyre pressures, as well as sizes, to be optimised for light load.)

• The Jensen GT (hatchback coupe) — was introduced in attempt to broaden the sales base of the Jensen Healey, which had up to that time been a roadster or convertible. Its road test report in Motor Magazine and a very similar one, soon after, in Road & Track concluded that it was no longer fun enough to drive to be worth that much money. They blamed it on minor suspension changes. Much more likely, the change in weight distribution was at fault. The Jensen Healey was a rather low and wide fairly expensive sports car, but the specifications of its suspension were not particularly impressive, having a solid rear axle. Unlike the AC Aceca, with its double transverse leaf rear suspension and aluminium body, the Jensen Healey could not stand the weight of that high up metal and glass and

still earn a premium price for its handling. The changes also included a cast iron exhaust manifold replacing the aluminium one, probably to partly balance the high and far back weight of the top. The car had also suffered reliability problems with engines that Jensen bought from Lotus. The factory building was used to build multi-tub truck frames.

Steering Steering is the term applied to the collection of components, linkages, etc. which allow for a car or other vehicle to follow a course determined by its driver, except in the case of rail transport by which rail tracks combined together with railroad switches provide the steering function.

Part of steering mechanism: tie rod, steering arm, king pin.

Introduction

The most conventional steering arrangement is to turn the front wheels using a hand–operated steering wheel which is positioned in front of the driver, via the steering column, which may contain universal joints to allow it to deviate somewhat from a straight line. Other arrangements are sometimes found on different types of vehicles, for example, a tiller or rear–wheel steering. Tracked vehicles such as tanks usually employ differential steering — that is, the tracks are made to move at different speeds or even in opposite directions to bring about a change of course.

Rack and pinion, recirculating ball, worm and sector

Rack and pinion animation

Many modern cars use rack and pinion steering mechanisms, where the steering wheel turns the pinion gear; the pinion moves the rack, which is a sort of linear gear which meshes with the pinion, from side to side. This motion applies steering torque to the kingpins of the steered wheels via tie rods and a short lever arm called the steering arm.

Older designs often use the recirculating ball mechanism, which is still found on trucks and utility vehicles. This is a variation on the older worm and sector design; the steering column turns a large screw (the "worm gear") which meshes with a sector of a gear, causing it to rotate about its axis as the worm gear is turned; an arm attached to the axis of the sector moves the pitman arm, which is connected to the steering linkage and thus steers the wheels. The recirculating ball version of this apparatus reduces the considerable friction by placing large ball bearings between the teeth of the worm and those of the screw; at either end of the apparatus the balls exit from between the two pieces into a channel internal to the box which connects them with the other end of the apparatus, thus they are "recirculated".

Rack and pinion unit here mounted in the cockpit of an Ariel Atom sports car chassies. For most high volume production this is usually mounted on other side of this panel

The rack and pinion design has the advantages of a large degree of feedback and direct steering "feel"; it also does not normally have any backlash, or slack. A disadvantage is that it is not adjustable, so that when it does wear and develop lash, the only cure is replacement.

The recirculating ball mechanism has the advantage of a much greater mechanical advantage, so that it was found on larger, heavier vehicles while the rack and pinion was originally limited to smaller and lighter ones; due to the almost universal adoption of power steering, however, this is no longer an important advantage, leading to the increasing use of rack and pinion on newer cars. The recirculating ball design also has a perceptible lash, or "dead spot" on center, where a minute turn of the steering wheel in either direction does not move the steering apparatus; this is easily adjustable via a screw on the end of the steering box to account for wear, but it cannot be entirely eliminated or the mechanism begins to wear very rapidly. This design is still in use in trucks and other large vehicles, where rapidity of steering and direct feel are less important than robustness, maintainability, and mechanical advantage. The much smaller degree of feedback with this design can also sometimes be an advantage; drivers of vehicles with rack and pinion steering can have their thumbs broken when a front wheel hits a bump, causing the steering wheel to kick to one side suddenly (leading to driving instructors telling students to keep their thumbs on the front of the steering wheel, rather than wrapping around the inside of the rim). This effect is even stronger with a heavy vehicle like a truck; recirculating ball steering prevents this degree of feedback, just as it prevents desirable feedback under normal circumstances.

The steering linkage connecting the steering box and the wheels usually conforms to a variation of Ackermann steering geometry, to account for the fact that in a turn, the inner wheel is actually traveling a path of smaller radius than the outer wheel, so that the degree of toe suitable for driving in a straight path is not suitable for turns.

Four-wheel steering

The system

Four-wheel steering (or all wheel steering) is a system employed by some vehicles to increase vehicle stability while maneuvering at high speed, or to decrease turning radius at low speed.

In most four-wheel steering systems, the rear wheels are steered by a computer and actuators. The rear wheels generally cannot turn as far as the front wheels.

Sports cars sometimes include 4-wheel steering for stability at high speeds. When performing an abrupt lane change at highway speeds, for example, a car with four-wheel steering will avoid rear suspension loading common in 2-wheel steering cars. Because the rear wheels steer in the same direction as the front wheels, the car is transitioned more gently into turning.

Alternatively, several systems (including Delphi's Quadrasteer and the system in Honda's Prelude line) allow for the rear wheels to be steered in the opposite direction as the front wheels during low speeds. This allows the vehicle to turn in a significantly smaller radius—sometimes critical for large trucks or vehicles with trailers.

Recent application

All four wheels turn at the same time when you steer. There are controls to switch off the rear steer and options to steer only the rear wheel independent of the front wheels. At slow speeds (e.g. parking) the rear wheels turn opposite of the front wheels, reducing the turning radius by up to twenty-five percent, while at higher speeds both front and rear wheels turn alike (electronically controlled), so that the vehicle may change position with less yaw, enhancing straight-line stability. The "Snaking effect" experienced during motorway drives while towing a caravan is thus largely nullified. Four-wheel steering found its most widespread use in monster trucks, where maneuverability in small arenas is critical, and it is also popular in large farm vehicles and trucks.

General Motors offers Delphi's Quadrasteer in their consumer Silverado/Sierra and Suburban/Yukon. However, only 16,500 vehicles have been sold with this system since its introduction in 2002 through 2004. Due to this low demand, GM will not offer the technology on the 2007 update to these vehicles.

Previously, Honda had four-wheel steering as an option in their 1988-1994 Prelude, and Mazda also offered four-wheel steering on the 626 and MX6 in 1988. Neither system was very popular, in that whatever improvement they brought to these already excellent-handling vehicles was offset by an unavoidable decrease in sensitivity caused by the increased weight and complexity.

Some vehicles now offer a form of "passive" four-wheel steering, where the bushings by which the rear suspension attaches to the automobile are designed to compress in a precise direction under the forces of steering, thus slightly altering the rear suspension geometry in such a manner as to enhance stability.

Cars with four wheel steering

• Citroën ZX • GMC Sierra (2002) • Honda Prelude (1988 and

1999) • Honda Accord (1991) • Infiniti M35 • Infiniti Q45 • Jeep Hurricane • Mazda 626 (1988) • Mazda MX-6 (1989-1997) • Mazda RX-7 (1986-1992) • Mitsubishi Galant VR-4 • Mitsubishi GTO (also sold

as the Mitsubishi 3000GT and the Dodge Stealth)

• Nissan Cefiro (A31) • Nissan 240SX (option on SE

models)

• Nissan 300ZX (all Twin-Turbo Z32 models) • Nissan Laurel (later versions) • Nissan Fuga • Nissan Silvia (option on all S13 models) • Nissan Skyline GTS, GTS-R, GTS-X (1986) • Nissan Skyline GT-R • Peugeot 306 • Toyota Aristo (1997) • Toyota Celica (option on 5th and 6th

generation, 1990-1995) • Volvo 850 (this had only passive rear steer

via compliant bushes) • Some German World War II vehicles; the

Schwere Panzerspähwagen (Sd Kfz 231) 8-Rad had both drive and steering on all eight wheels.

Articulated steering

A front loader with articulated steering.

Articulated steering is a system by which a four-wheel drive vehicle is split into front and rear halves which are connected by a vertical hinge. The front and rear halves are connected with one or more hydraulic cylinders that change the angle between the halves, including the front and rear axles and wheels, thus steessring the vehicle. This system does not use steering arms, king pins, tie rods, etc. as does four-wheel steering. If the vertical hinge is placed equidistant between the two axles, it also eliminates the need for a central differential, as both front and rear axles will follow the same path, and thus rotate at the same speed.

Power Steering

Power steering aims to make steering less strenuous for the driver. There are two types of power steering systems—hydraulic and electric/electronic. There is also a hydraulic-electric hybrid system possible.

A hydraulic power steering (HPS) uses hydraulic pressure supplied by an engine-driven pump. Electric power steering (EPS) is more efficient than the hydraulic power steering, since the electric power steering motor only needs to provide assist when the steering wheel is turned, whereas the hydraulic pump must run constantly. In EPS the assist level is easily tunable to the vehicle type, road speed, and even driver preference. An added benefit is the elimination of environmental hazard posed by leakage and disposal of hydraulic power steering fluid.

Steer-By-Wire

The aim of steer-by-wire technology is to completely do away with as many mechanical components (steering shaft, column, gear reduction mechanism, etc.) as possible.

Completely replacing conventional steering system with steer-by-wire holds several advantages, such as:

• The absence of steering column simplifies the car interior design.

• The absence of steering shaft, column and gear reduction mechanism allows much better space utilization in the engine compartment.

• The steering mechanism can be designed and installed as a modular unit.

• Without mechanical connection between the steering wheel and the road wheel, it is less likely that the impact of a frontal crash will force the steering wheel to intrude into the driver's survival space.

• Steering system characteristics can easily and infinitely be adjusted to optimize the steering response and feel.

Safety

For safety reasons all modern cars feature a collapsible steering column which will collapse in the event of a heavy frontal impact to avoid excessive injuries to the driver. This safety feature first appeared on cars built by General Motors after an extensive and very public lobbying campaign enacted by Ralph Nader.

Cycles

Steering is crucial to the stability of bicycles and motorcycles (see article on bicycle).

Mechanical engineering

Mechanical engineers design and build engines and power plants...

...structures and vehicles of all sizes...

...and moving mechanisms, machines, and robots.

Mechanical engineering is a professional engineering discipline that involves the application of principles of physics for analysis, design, manufacturing, and maintenance of mechanical systems. It requires a solid understanding of key concepts including mechanics, kinematics, thermodynamics and energy. Practitioners of mechanical engineering, known as mechanical engineers, use these principles and others in the design and analysis of automobiles, aircraft, heating & cooling systems, buildings and bridges, industrial equipment and machinery, and much more.

Development of mechanical engineering

Before the Industrial Revolution, most engineering was restricted to military and civil uses. Engineers in the military, though not always referred to as such, designed fortification systems and various war machines. Civil engineers were responsible primarily for structures. "During the early 19th century in England mechanical engineering developed as a separate field to provide manufacturing machines and the engines to power them. The first British professional society of civil engineers was formed in 1818; that for mechanical engineers followed in 1847." In the United States, the first mechanical engineering professional society was formed in 1880, making it the third oldest type of engineering behind civil (1852) and mining & metallurgical (1871). "The first schools in the United States to offer an engineering education were the United States Military Academy in 1817, an institution now known as Norwich University in 1819, and Rensselaer Polytechnic Institute in 1825. An engineering education is based on a strong foundation in mathematics and science; this is followed by courses emphasizing the application of this knowledge to a specific field and studies in the social sciences and humanities to give the engineer a broader education."

Education

A Bachelor of Arts (BA) or Bachelor of Science (BS) degree in mechanical engineering is offered at many universities in the United States, and similar programs are offered at universities in most industrialized nations. In the U.S., mechanical engineering programs typically take four to five years and result in a B.S.M.E./B.A.M.E., or Bachelor of Science/Arts in Mechanical Engineering. Most mechanical engineering programs are accredited nationally by ABET to ensure similar course requirements and standards between universities. The ABET website lists 276 accredited mechanical engineering programs as of June 19, 2006.

Some mechanical engineers go on to pursue a postgraduate degree such as a Master of Engineering/Master of Science, a Master of Engineering Management, a Doctor of Philosophy in Engineering or an Engineer's degree. The Master and Engineer's degree may consist of either research, coursework or a mixture of the two. The Doctor of Philosophy consists of a significant research component and is often viewed as the entry point to academia.

Some of the best schools for mechanical engineering include: California Institute of Technology, Massachusetts Institute of Technology, and Georgia Institute of Technology.

After being awarded a degree, engineers may seek licensure by a state government. To become a licensed Practicing Engineer, an engineer must

• pass the comprehensive FE (Fundamentals of Engineering) exam, • work a given number of years as an Engineer in Training (EIT), • pass the PE (Practicing Engineer or Professional Engineer) exam.

The purpose of this process is to ensure that engineers possess the necessary technical knowledge and real-world experience to engineer safely. Not every mechanical engineer chooses to become licensed; those that do can be distinguished as Practicing Engineers by the post-nominal title PE, as in: Jane Doe, PE. A distinction similar to practicing engineer status is the Chartered Engineer ('CEng') status awarded by some European, Asian and Oceanic engineering organizations. "In most modern countries, certain engineering tasks, such as the design of bridges, electric power plants, and chemical plants, must be approved by a Professional Engineer or a Chartered Engineer."

Mechanical engineering coursework

American Universities offering accredited programs in mechanical engineering are required to offer several major subjects of study, as determined by ABET. This is to ensure a minimum level of competence among graduating engineers and to inspire confidence in the engineering profession as a whole. The specific courses required to graduate, however, differ from program to program. Universities will often combine multiple subjects into a single class or split a subject into multiple classes, depending on the faculty available and the University's major area(s) of research. Fundamental subjects of mechanical engineering typically include:

• statics & dynamics • strength of materials • solid mechanics, • instrumentation and measurement, • thermodynamics, heat transfer, energy conversion, and refrigeration / air

conditioning, • fluid mechanics and dynamics, • mechanism design (including kinematics and dynamics), • manufacturing technology or processes, • engineering design,

• mechatronics and/or control theory, • drafting or CAD/CAM.

Mechanical engineers are also expected to understand and be able to apply basic concepts from chemistry, chemical engineering, electrical engineering, and physics. Most mechanical engineering programs include several semesters of calculus, as well as advanced mathematical concepts which may include differential equations and partial differential equations, linear and modern algebra, and differential geometry, among others.

In addition to the core mechanical engineering curriculum, many mechanical engineering programs offer more specialized programs and classes, such as mechatronics / robotics, transport and logistics, cryogenics, fuel technology, automotive engineering, biomechanics, vibration, optics and others, if a separate department does not exist for these subjects.

Most mechanical engineering programs also require varying amounts of research or community projects to gain practical problem-solving experience. Mechanical engineering students usually hold one or more internships while studying, though this is not typically mandated by the university.

Salaries and workforce statistics

The total number of engineers employed in the U.S. in 2004 was roughly 1.4 million. Of these, 226,000 were mechanical engineers (15.6%), second only in size to civil engineers at 237,000 (16.4%). The total number of mechanical engineering jobs in 2004 was projected to grow 9 to 17%, with average starting salaries being $50,236 with a bachelors degree, $59,880 with a masters degree, and $68,299 with a doctorate degree. This places mechanical engineering at 8th of 14 among engineering bachelors degrees, 4th of 11 among masters degrees, and 6th of 7 among doctorate degrees in average annual salary.The median annual earning of mechanical engineers in the U.S. workforce is roughly $63,000. This number is highest when working for the government ($72,500), and lowest when doing general purpose machinery manufacturing in the private sector ($55,850).[9]

Canadian engineers make an average of $28.10 per hour with 3% unemployed. The average for all occupations is $16.91 per hour with 5% unemployed. Eight percent of

these engineers are self-employed, and since 1994 the proportion of female engineers has remained constant at 4%.[10]

Process of Mechanical Engineering

The process of mechanical engineering is optimization: engineers strive to optimize the cost, producibility, durability, safety, and overall usefulness of objects. This process can be as simple as the design of a chair for comfort or as complex as the optimization of a turbocharged engine for speed. It can be as small as the cutting of a nano-sized gear or as large as the assembly of a supertanker used to carry oil around the world.

Tools and Work

Modern analysis and design processes in mechanical engineering are aided by various computational tools including FEA, CFD, and CAD/CAM.

Subdisciplines

The field of mechanical engineering can be thought of as a collection of many mechanical disciplines. Several of these subdisciplines which are typically taught at the undergraduate level are listed below, with a brief explanation and the most common application of each. Some of these subdisciplines are unique to mechanical engineering, while others belong to mechanical engineering and one or more other disciplines. Most work that a mechanical engineer does uses skills and techniques from several of these subdisciplines, as well as specialized subdisciplines. Specialized subdisciplines as defined here are usually the subject of graduate more than undergraduate research. Several specialized subdisciplines are discussed at the end of this section

Mechanics

Mechanics

Mohr's circle, a common tool to study stresses in a mechanical element

Mechanics is, in the most general sense, the study of forces and their effect upon matter. Typically, engineering mechanics is used to analyze and predict the acceleration and deformation (both elastic and plastic) of objects under known forces (also called loads) or stresses. Subdisciplines of mechanics include

• Statics, the study of non-moving bodies under known loads • Dynamics (or kinetics), the study of how forces affect moving bodies • Mechanics of materials, the study of how different materials deform under various

types of stress • Fluid Mechanics, the study of how fluids react to forces. Note that fluid

mechanics can be further split into fluid statics and fluid dynamics, and is itself a subdiscipline of continuum mechanics. The application of fluid mechanics in engineering is called hydraulics.

• Continuum mechanics is a method of applying mechanics that assumes that objects are continuous. It is contrasted by discrete mechanics.

Uses

Mechanical engineers typically use mechanics in the design or analysis phases of engineering. If the engineering project were the design of a vehicle, statics might be employed to design the frame of the vehicle, to evaluate where the stresses will be most intense. Dynamics might be used when designing the car's engine, to evaluate the forces in the pistons and cams as the engine cycles. Mechanics of materials might be used to choose an appropriate material for the frame or engine. Fluid mechanics might be used to design a ventilation system for the vehicle (see HVAC), or to design the intake system for the engine.

Kinematics

Kinematics

Kinematics is the study of the motion of bodies and systems, while ignoring the forces that cause the motion. The movement of a crane and the oscillations of a piston in an engine are both simple kinematic systems. The crane is a type of open kinematic chain, while the piston is part of a closed four bar linkage.

Uses

Mechanical engineers typically use kinematics in the design and analysis of mechanisms. Kinematics can be used to find the possible range of motion for a given mechanism, or, working in reverse, can be used to design a mechanism that has a desired range of motion.

Mechatronics & Robotics

Mechatronics is an interdisplinary branch of mechanical engineering, electrical engineering and software engineering that is concerned with integrating electrical and mechanical engineering to create hybrid systems. In this way, machines can be automated through the use of electric motors, servo-mechanisms, and other electrical systems in conjunction with special software. A common example of a mechatronics system is a CD-ROM drive. Mechanical systems open and close the drive, spin the CD and move the laser, while an optical system reads the data on the CD and converts it to bits. Integrated software controls the process and communicates the contents of the CD to the computer.

Uses

Mechatronics is currently used in the following areas of engineering:

• Automation, and in the area of robotics. • Servo-Mechanics • Sensing and Control Systems • Automotive engineering, in the design of subsystems such as anti-lock braking

systems • Computer engineering, in the design of mechanisms such as hard drives, CD-

ROM drives, etc.

Industrial robots perform repetitive tasks, such as assembling vehicles.

Robotics is the application of mechatronics to create robots, which perform tasks that are dangerous, unpleasant, or repetitive. These robots may be of any shape and size, but all are a) preprogrammed and b) interact physically with the world. To create a robot, an engineer typically employs kinematics (to determine the robot's range of motion) and mechanics (to determine the stresses within the robot).

Uses

Robots are used extensively in Industrial engineering. They allow businesses to save money on labor and perform tasks that are either too dangerous or too precise for humans to perform them economically. Many companies employ assembly lines of robots, and some factories are so reboticized that they can run by themselves. Outside the factory, robots have been employed in bomb disposal, space exploration, and many other fields. Robots are also sold residentially (see Roomba).

Structural failure analysis

Structural failure analysis or just failure analysis is the branch of mechanical engineering devoted to examining not only why but how objects break or otherwise fail. Structural failures occur in two modes: static failure and fatigue failure. Static structural failure occurs when, upon being loaded (having a force applied) the object being analyzed either breaks or is deformed plastically, depending on the criterion for failure. Fatigue failure occurs when an object fails after a number of cycles, or repeated loadings and unloadings. Fatigue failure occurs because of imperfections in the object. A microscopic crack on the surface of the object is one type of imperfection, and it will

grow slightly with each cycle (propagation) until the crack is large enough to cause failure.

Failure is not defined as when a part breaks, however; it is defined as when a part does not operate as intended. Some systems, such as the perforated top sections of some plastic bags, are designed to break. If these systems do not break, failure analysis might be employed to determine the cause.

Uses

Failure analysis is often used by mechanical engineers after a failure has occurred, or while performing maintenance. This differs from the other subdisciplines of mechanical engineering, which are generally employed before any parts have been fabricated. Engineers may use handbooks such as those published by ASM to aid them in determining the type of failure and possible causes.

Failure analysis may be used both in the field, to analyze failed parts, and in laboratories, where parts might undergo controlled failure tests.

Thermodynamics and thermo-science

Thermodynamics is a branch of both mechanical engineering and Chemical Engineering. At its simplest, thermodynamics is the study of how energy moves through a system. Typically, engineering thermodynamics is concerned with changing energy from one form to another. Engines, for instance, change enthalpy, the stored energy in molecules, into heat and then into mechanical work that eventually turns the wheels.

Uses

Thermodynamics principles are used by mechanical engineers in the fields of heat transfer, thermofluids, and energy conversion. Mechanical engineers use thermo-science to design engines and power plants, heating, ventilation, and air-conditioning (HVAC) systems, heat exchangers, heat sinks, radiators, refrigeration, insulation, and others.

Drafting

A CAD model of a mechanical double seal

Technical drawing

Drafting or technical drawing is the mean by which mechanical engineers create instructions for manufacturing parts. A technical drawing can be a computer model or hand-drawn schematic showing all the dimensions necessary to manufacture a part, as well as assembly notes, a list of required materials, and other pertinent information. A U.S. mechanical engineer or skilled worker who creates technical drawings may be referred to as a drafter or draftsman (or, more correctly, draftsperson). Drafting has historically been a two-dimensional process, but recent Computer-Aided Drafting (CAD) programs have begun to allow the designer to create in three dimensions.

Instructions for manufacturing a part must be fed to the necessary machinery, either manually, through programmed instructions, or through the use of a Computer-Aided Manufacturing (CAM) or combined CAD/CAM program. Optionally, an engineer may also manually manufacture a part using the technical drawings, but this is becoming an increasing rarity, except in the areas of applied spray coatings, finishes, and other processes that cannot economically be done by a machine.

Uses

Drafting is used in nearly every subdiscipline of mechanical engineering, and by many other branches of engineering and architecture. Three-dimensional models created using CAD software are also commonly used in Finite element analysis (FEA) and Computational fluid dynamics (CFD).

List of specialized subdisciplines

The following is a list of some additional subdisciplines and topics within mechanical engineering. These topics may be considered specialized because they are not typically

part of undergraduate mechanical engineering requirements, or require training beyond an undergraduate level to be useful.

• Acoustical Engineering • Aerospace Engineering • Alternative Energy • Automotive Engineering • Biomedical Engineering • Computer-Aided Engineering • Heating, Ventilation, and Air Conditioning (HVAC) • Nanotechnology • Nuclear Engineering • Piping • Power Generation • Engineering Based Programming • Robotics*

*Robotics is also listed as a general subdiscipline, but because of the breadth of the subject it may require many years of advanced training to be useful to a particular field.

Frontiers of research in mechanical engineering

Mechanical engineering is not a static field of engineering. Mechanical engineers are constantly pushing the boundaries of what is physically possible in order to produce safer, cheaper, and more efficient machines and mechanical systems. Some technologies at the cutting edge of mechanical engineering are listed below ( exploratory engineering).

Nanotechnology

At the smallest scales, mechanical engineering becomes nanotechnology and molecular engineering - one speculative goal of which is to create a molecular assembler to build molecules and materials via mechanosynthesis. For now this goal remains within exploratory engineering.

Nuclear fusion

Nuclear fusion and Fusion Power

Most nuclear power plants today work on the principle of nuclear fission. An international effort is currently underway to explore the potential of nuclear fusion as a cleaner alternative energy source, and an experimental 500 MW power plant known as ITER is currently under construction in France.[11]

Electronic Stability Control

Electronic Stability Control (ESC) is the generic term for systems designed to improve a vehicle's handling, particularly at the limits where the driver might lose control of the vehicle.

Robert Bosch GmbH were the first to deploy an ESC system, called Elektronisches Stabilitätsprogramm (ESP®) that was used first by Mercedes-Benz and BMW in 1995. It was then introduced to the mass market by Continental Automotive Systems under the broader name of Electronic Stability Control, which is now the more common term recognized by the Society of Automotive Engineers, although individual motor manufacturers use a range of different marketing names (see below).

Operation

ESC compares the driver's intended direction in steering and braking inputs, to the vehicle's response, via lateral acceleration, rotation (yaw) and individual wheel speeds. ESC then brakes individual front or rear wheels and/or reduces excess engine power as needed to help correct understeer (plowing) or oversteer (fishtailing). ESC also integrates all-speed traction control, which senses drive-wheel slip under acceleration and individually brakes the slipping wheel or wheels, and/or reduces excess engine power, until control is regained. ESC cannot override a car's physical limits. If a driver pushes the possibilities of the car's chassis and ESC too far, ESC cannot prevent a crash. It is a tool to help the driver maintain control.

ESC combines anti-lock brakes, traction control and yaw control (yaw is spin around a vertical axis).

Effectiveness

Numerous international studies have confirmed the effectiveness of ESC in helping the driver maintain control of the car, help save lives and reduce the severity of crashes. In the fall of 2004 in the U.S., the National Highway and Traffic Safety Administration confirmed the international studies, releasing results of a field study in the U.S. of ESC effectiveness. NHTSA concluded that ESC reduces crashes by 35%. The Insurance Institute for Highway Safety (IIHS) later issued their own study that concluded the widespread application of ESC could save 7,000 lives a year. In June 2006, the IIHS updated the results of their 2004 study by stating that up to 10,000 fatal crashes could be avoided annually if all vehicles were equipped with ESC.That makes ESC the greatest safety equipment development since seat belts, according to some experts. However, some people contend (backed up by the theory of risk compensation) that the perception of safety conferred by the ESC will encourage more dangerous driving, as seems to be the case with seat belts. Among those concerned that ESC is just the latest example of a long and ultimately unsuccessful campaign, in the U.S. and abroad, to make cars that are capable of compensating for dangerous driving behavior is the Partnership for Safe Driving www.crashprevention.org. The Partnership believes that if no corresponding effort is made to deter speeding, aggressive, distracted and drowsy driving, this technology will not live up to its promise and may, in fact, encourage even more dangerous driving behavior.

Criticism

Some driving enthusiasts, most publicly motoring journalists from enthusiast magazines, object to some of the implementations of ESC. They contend that by making it impossible to explore the dynamic behaviour of their cars, overzealous ESC systems spoil much of the fun of driving. Consequently, some manufacturers allow drivers to disable ESC systems, and/or use ESP systems that allow greater levels of under or oversteer before it intervenes. Some even provide a setting so the user can choose whether the system will intervene earlier or later stage. Enthusiasts have also begun to modify ESC systems to suit their preferred driving styles .

It has also been argued that ESC is being used as a "catch all" for poorly designed cars, whereby the basic mechanical handling of a car is unstable and ESC is used to compensate for the problem.

Another point of critique is that in the case of very dangerous drivers, the car will be able to be pushed further (and faster) before the limits of the vehicle and ESC are reached, meaning that should the vehicle become "out of control" this will happen at higher speeds, leading to more severe crashes.

Product Names

Vehicle manufacturers use electronic stability control systems under different marketing names:

• Acura: Vehicle Stability Assist (VSA) • Alfa Romeo: Vehicle Dynamic Control (VDC) • Audi: ESP - Electronic Stabilization Program • Buick: StabiliTrak • BMW: Dynamic Stability Control (DSC), including Dynamic Traction

Control • Cadillac: All-Speed Traction Control & StabiliTrak • Chevrolet: StabiliTrak (except Corvette - Active Handling) • Chrysler: Electronic Stability Program (ESP) • Dodge: Electronic Stability Program (ESP) • DaimlerChrysler: Electronic Stability Program (ESP) • Fiat: Electronic Stability Program (ESP) and Vehicle Dynamic Control

(VDC) • Ferrari: Controllo Stabilità (CST) • Ford: AdvanceTrac and Interactive Vehicle Dynamics (IVD); Dynamic

Stability Control (DSC) (Australia only); Electronic Stability Program (ESP) • GM: StabiliTrak • Hyundai: Electronic Stability Control • Honda: Electronic Stability Control (ESC) and Vehicle Stability Assist (VSA)

and Electronic Stability Program (ESP) • Holden: Electronic Stability Program (ESP) • Infiniti: Vehicle Dynamic Control (VDC) • Jaguar: Dynamic Stability Control (DSC) • Jeep: Electronic Stability Program (ESP) • Kia: Electronic Stability Program (ESP) • Land Rover: Dynamic Stability Control (DSC)

• Lexus: Vehicle Dynamics Integrated Management (VDIM) with Vehicle Stability Control (VSC) and Traction Control (TRAC) systems

• Lincoln: AdvanceTrak • Maserati: Maserati Stability Program (MSP) • Mazda: Dynamic Stability Control • Mercedes: Electronic Stability Program (ESP) • Mercury: AdvanceTrak • MINI Cooper: Dynamic Stability Control • Mitsubishi: Active Skid and Traction Control MULTIMODE • Nissan: Vehicle Dynamic Control (VDC) • Oldsmobile: Precision Control System (PCS) • Opel: Electronic Stability Program (ESP) • Peugeot: Electronic Stability Program (ESP) • Pontiac: StabiliTrak • Porsche: Porsche Stability Management (PSM) • Renault: Electronic Stability Program (ESP) • Rover: Dynamic Stability Control (DSC) • Saab: Electronic Stability Program • Saturn: StabiliTrak • SEAT: Electronic Stability Program (ESP) • Škoda: Electronic Stability Program (ESP) • Subaru: Vehicle Dynamics Control Systems (VDCS) • Suzuki: Electronic Stability Program (ESP) • Toyota: Vehicle Dynamics Integrated Management (VDIM) with Vehicle

Stability Control (VSC) • Vauxhall: Electronic Stability Program (ESP) • Volvo: Dynamic Stability and Traction Control (DSTC) • VW: Electronic Stability Program (ESP)

Future

Electronic Stability Control forms the foundation for new advances on vehicle equipment that will save additional lives and give the driver still more control over the vehicle. The computing power of ESC facilitates the networking of active and passive safety systems on the car, creating the opportunity to address still more causes of crashes.

The market for this system is growing at a very robust rate, especially in European countries such as Sweden and Germany. Despite criticism, it is expected that the ESC system will be installed in most vehicles post 2015 in most countries in Europe and also in Japan.

In the US, the NHTSA has recently mandated that ESC be included on every new vehicle by the model year 2012 (September, 2011).s

Vehicle dynamics • Vehicle dynamics is the Dynamics of Vehicles, here assumed to be ground

vehicles.

It is a part of engineering primarily based on classical mechanics but it may also involve chemistry, solid state physics, electrical engineering, communications, psychology etc.

Definitions

• Ackermann steering geometry • Camber angle • Caster angle • Circle of forces • Electronic Stability Control • Live axle • Oversteer • Roll center • Toe • Understeer • Unsprung weight • Weight transfer

Performance driving techniques

• Cadence braking • Threshold braking • Double declutching • Drifting (motorsport) • Handbrake turn • Heel-and-Toe • Left-foot braking • Opposite lock

Uberdata

A screen shot of Uberdata 1.70

Uberdata (also known as Überdata or Uber data) is a ROM editing software designed specifically for [[On Board Diagnostics] (OBD) Honda Engine control units. It was created by Blake Warner (also known as Uberteg or Vertigo). In an article Warner states that "Uberdata is, in short, a piece of software that enables you to modify your Honda ECU's code using a windows-based program". (source Honda Tuning Magazine; June 2005)

The current stable release is 1.70 (which was officially released on 10/24/04). The future of Uberdata is uncertain because Warner stopped developing the program and chose not to divulge the source code to the public.

Engine swap

A Saab 99 with a 16 valve turbo engine from a Saab 900.

An engine swap is the process of rsemoving a car's engine and replacing it with another; this is done either because of failure, or to install a different engine, usually one that is more powerful or more up to date and maintainable.

While one can work wonders with engine tuning to achieve greater power, the same techniques applied to a better engine are unlikely to be much more expensive and may be much more rewarding.

An engine swap can either be to another engine intended to work in the car by the manufacturer, or one totally different. The former is much simpler than the latter, of

course. To fit an engine the car was never intended to take may require much work -- modifying the car to fit the engine, modifying the engine to fit the car, and building such things as custom engine mounts to interface them.

A common anecdote among tuners is that the easiest way to make a car faster is to drop in a Corvette engine or a small block 350 and be done with it. Other popular engine swaps are putting a Porsche engine in a VW Beetle or a turbocharged engine from a Saab 900 in a Saab 99 or BMW.

In the world of sport compact enthusiasts, engine swaps are common with Nissans and Hondas. A stock US Spec Nissan 240SX produces 160 hp in stock form with its torquey KA24DE 160 hp engine. Swapped out with a Japanese SR20DET, a Nissan 240SX will produce over 200 hp right out of the box, with mild modifications that can increase power anywhere from 250 hp to 300 hp.

In the Honda world, popular engine swaps include the Civic Si (B16A), Integra GSR(B18C), and the Integra Type R (B18C5) engines. Swapping it into a 88-00 lighter Honda Civic chassis, greater performance can be achievable. Not for the novices, other high-powered and less common swaps include the RSX Type S (K20A), and the Prelude (H22A) engine swap.

Engine swaps are also somewhat common within the Volkswagen tuning scene, often placing Mark III and Mark IV engines such as the VR6 and the 1.8 T into the Mark II GTI, Jetta and Corrado. Less common is the swap into a Mark 1 Rabbit or Cabriolet, giving an amazing power to weight ratio even with minimally modified powerplants.

How to Attach a Battery Cut off Switch There are three types of switches. First, a master switch. Second, a manual switch. And third, an electronic switch. A master switch is installed on the battery, and is mostly used to prevent battery loss and for long term storage. A manual switch goes inside the car, and works like a master switch. An electronic switch is controlled by car alarms (mostly). These instructions are for a master switch.

Steps 1. Buy a switch. Make sure that the switch is rated to handle the load of a car

battery. Expect to pay over $20 for it. Example 2. Disconnect the ground/black battery cable (or red/positive if instructions say so). 3. Connect the switch to the now unconnected battery lug. 4. Connect the disconnected battery cable to the switch. 5. Turn the switch on and test the car.

Tips • If you need to do this with a manual switch, consult a mechanic. • Some electrical and mechanical knowledge is required for manual and electronic

switches. • Disconnecting the battery on newer vehicles will erase the "learned memory" of

the computers and may affect the way the car runs. • Inexpensive, Small power suppliers (using a nine volt battery), that plug into any

powerpoint or cigarette lighter, can be purchased to keep computer memories and security codes from clearing.

Warnings • Be careful of any new installation that requires splicing of wires. Any sloppy

connections can result in a short. As a matter of precaution, always install a fuse as well.

How to Calculate Your Car's Fuel Efficiency (MPG)

As gas prices rise, fuel efficiency is becoming more and more of a critical factor. Knowing your car's MPG (that is, how many miles it gets per gallon) can help you determine if it's is a gas guzzler that's eating up your wallet as well. Once you figure out the MPG, you can do many useful things, like calculate how much a $.10 rise in gas prices will affect your budget, or how getting a car with better MPG will lower your monthly costs.

Steps 1. Go to the gas station and fill up the fuel tank. 2. Record the mileage, before even pulling away from the pump. We will call this

Mileage A. 3. Drive normally until the tank is less than half full. 4. Fill up the tank again. This time, pay attention to how many gallons it takes to fill

up the tank. This is usually shown at the pump. 5. Record the mileage again, just like before. We will call this Mileage B. 6. Subtract Mileage A from Mileage B. This will give you the number of miles you

drove since your last fill-up. 7. Divide your answer by the number of gallons it took to fill up your tank. This will

give you your car's MPG.

Tips • The higher the MPG, the more efficient your car is, and the cheaper it'll be to

keep it fueled. • To determine how a change in gas prices will affect your budget, take the number

of miles you expect to drive in a week (or a month, or a year) and divide it by your MPG. Then multiply that answer by the price of gas per gallon. By plugging in different prices, you'll see how much more - or less - you end up paying per week (or per month, or per year).

• Try calculating your MPG more than once to get a more accurate measurement. If you did more highway driving than normal, then your MPG will be a little higher. On the flip side, if you did a little extra city (stop and go) driving, your MPG will be lower.

• You can use the MPG to experiment with ways to increase fuel efficiency. For example, if you normally drive at an average of 70 MPH, then after calculating your MPG, try driving at 55 MPH and measure your MPG again - you'll probably see it go up.

• Mileage will vary with different driving patterns, the less braking and acceleration will lead to better mileage. You will see higher mileage when taking highway trips than you will after a week of driving back and forth to work on city streets.

How to Clear Foggy Headlight Covers

Cleaning covers is far less expensive than replacing them.

Steps 1. Take a sheet of 500 grit sandpaper. 2. Wet the cover, then rub side-to-side with sandpaper, ensuring you clean the entire

cover. 3. Rinse well. 4. Dry the cover by rubbing it with a good rubbing compound (such as 3-M). 5. Rub in a circular motion for about 5 minutes, then wipe off the compound. 6. Buff the covers using a dry cotton cloth. (You may have to repeat this process one

to three times if the cover was badly fogged.) 7. Polish the cover with car wax.

Tips • It's best to do this task in the shade, not in direct sunlight. • Be sure to buff off all the rubbing compound before you apply car wax.

Warnings • Don't use a power polisher! The covers are plastic and the heat from the friction

will damage them.

Things You'll Need • 500-grit sandpaper. • Liquid rubbing compound -- fine. • A bucket of warm water. • Several cotton rags. • Car wax.

How to Change a Tire

Have you ever gotten stuck helplessly on the side of the road with a flat tire, or do you dread someday getting trapped in that kind of scenario? Do you want to be able to change a tire without having to ask for help? Luckily for you, changing a tire is a pretty simple task, if you don't mind a little bit of elbow grease!

Steps 1. Make sure that you are on stable ground (avoid hills). If possible, it is a good idea

to place a heavy object (such as a brick) in front of the front tire (if changing a rear tire), and vice versa.

2. Get the spare tire and the jack. Place the jack under the frame near the tire that you are going to change. Make sure that you place it where it will meet the metal portion of the frame. Many cars are made from molded plastic, and if you don't place the jack in the right spot, it will crack the body when you start lifting.

3. Prior to lifting, remove the hub cap and loosen the nuts about 1/3 to 1/2 of the way.

4. Pump the jack to lift the tire off the ground. 5. Loosen lugnuts with a cross wrench. Place the right size of the wrench on the

lugnunt and spin counter clockwise until it's loose. Repeat this with all lugnuts, then remove the nuts completely.

6. Remove the tire.

7. Place the flat tire under the vehicle so in event of jack failure the vehicle will fall on the old wheel hopefuly preventing injury. If the jack is placed on a flat, solid base, you shouldn't have any problems!

8. Place the spare tire on the wheel, taking care to align the rim of the spare tire with the wheel bolts, and tighten the nuts as much as possible. To ensure the tire is balanced, don't completely tighten the nuts one at a time. Going in a circle around the tire, one nut after another, give each one a full turn until they are equally tight.

9. Lower the car to the ground, but do not put full weight on it yet. Finish tightening the nuts as much as possible.

10. Lower the car to the ground fully. Remove the jack. Tighten the nuts again. 11. Replace the hubcap. 12. Put the old tire in your trunk and take it to a mechanic. Small puncture wounds

can usually be repaired for less than $10. If the tire is not repairable, they can dispose of it properly.

Tips • Loosen the nuts prior to lifting with the jack. • Tighten as much as a possible prior to lowering to the ground. • If your wheels have locking lug nuts, be sure to keep the key-lug where you can

easily find it. You will need it to change the tire. • Be advised that most spare tires are not rated for more than 50 MPH. Exceeding

this speed can cause severe issues, including failure of the spare tire. • When loosening and tightening the nuts, arrange the cross wrench so that you are

pressing down (with gravity). This will remove risk of injury to your back and also allow you to use your body weight rather than just your arm strength.

Warnings • Do not use the lug wrench to start off the lug nuts when putting them back on.

Use your hands, as this will prevent from misthreading the lug.

• Be aware of your surroundings. If you're on a busy road, be particularly wary of vehicles driving by that might get too close.

• Watch out for "good Samaritans" with bad intentions. Unfortunately, there are malicious folks out there, and if you're a woman stuck on the road in the middle of nowhere and it's dark, you should be especially cautious

How to Correctly Change a Flat Tire This instruction will show you how to change a flat tire if you already don't know how. Enjoy.

Steps 1. If you are driving while you experience a flat tire, pull over to the shoulder to the

road as quickly and safely as possible. 2. After you come to a stop, put your vehicle in park and turn off your car. 3. Turn on your hazard lights if it is dark out and there are no street lights around to

inform other drivers that you are on the side of the road. 4. Next, pull up or push the emergency brake to ensure the vehicle does not roll.

This is a crucial step for later on. 5. Exit your vehicle and check all your wheels to find which tire has gone flat. 6. After you have located the flat tire, search the trunk of your car for the car jack,

wheel wrench, and spare tire to replace the flat one. Secure the wheel opposite to the flat with some kind of rock or piece of wood to ensure that the vehicle does not move.

7. Get yourself situated and using the wrench, replace the screws holding the tire in place, starting with the one closest to the top. The screws may be screwed in very tightly so in order to loosen them, you may have to step on the wrench and very gently begin to bounce on it to get it loose. Make sure you do not jump too hard to break the wrench. Do not completely remove the screws, only loosen them. Make sure they remain on the wheel before step 8.

8. Now, take the car jack and find a spot underneath the area of the flat tire that you can place the jack under. It is important that you find the safe spot or else the car may drop. When you have located the appropriate spot, turn the jack so it slowly goes up, and takes the car up with it. Continue this until the tire is far enough off the ground to be replaced by a tire full of air.

9. After the wheel is in the air, you can now remove the screws and remove the tire from the wheel.

10. Take the spare tire and place it in the corresponding spot so you can place the screws into the correct spots.

11. Place the screws back into the holes, tightening them so that the tire will not move upon the lowering in the next step.

12. Go to the jack and lower the car back to normal level and remove the jack.

13. Tighten the screws back into place using the same but opposite method used in step 7. This time step on the jack and tighten it the opposite way. Make sure the screws are very tight before finishing this step.

14. After all the screws have been replaced, put all the equipment and the flat tire back into the trunk.

15. Get back into your car and turn off the hazard lights, take the emergency brake off, and turn your car back on.

16. Put your car into park and continue to your destination.

Tips • After you have completed this, take your flat tire to a mechanic or your nearby car

dealer as soon as possible to either fix the flat or get a replacement tire.

Warnings • Make sure your car is visible and make sure the emergency brake is on.

How to Fix Cars Air Conditioning Have you been sweltering in your car because of a broken air conditioner? Here's a short guide to how air conditioning (AC) works, why it might not work, and what you can do about it.

Steps 1. Realize that auto AC is basically a refrigerator in a weird layout. It's designed to

move heat from one place (the inside of your car) to some other place (the outdoors). While a complete discussion of every specific model and component is well outside the scope of this article, this should give you a start on figuring out what the problem might be and either fixing it yourself or talking intelligently to someone you can pay to fix it.

2. Become familiar with the five major components to auto air conditioning:

o the compressor, which compresses the refrigerant in the system (on modern cars, usually a substance called R-134a)

o the refrigerant, which carries the heat o the condensor, which gets hot when the compressed refrigerant goes

through it o the expansion valve, which isn't really a valve at all but more like a nozzle

o the dryer/evaporator, which adds heat to the refrigerant, cooling your car 3. Understand the air conditioning process: The compressor puts the refrigerant

under pressure and sends it to the condensing coils. In your car, these coils are generally in front of the radiator. Compressing a gas provides two results: First, the gas gets quite hot. When it is very hot, the outside air is cooler and heat can leave the gas. When the gas has cooled, remember that it is under pressure; it condenses into a liquid and this phase change makes it hotter. The refrigerant now loses huge amounts of heat. The liquid is then sent to the evaporator, the coils inside of your car. It is still a bit hot, but it is a liquid under pressure. There it goes through the expansion valve, finds a low pressure and evaporates. Evaporation requires a lot of heat energy, so the vapor gets cold. It is this phase change from liquid to gas that really causes the temperature to change. This cold gas vapor chills the evaporator, and your car's blower blows air through the cold evaporator and into the interior. The refrigerant goes back through the cycle again and again.

4. Check to see if all the R-134a leaks out (meaning there's nothing in the loop to carry away heat). Leaks are easy to spot but not easy to fix without pulling things apart. Most auto-supply stores carry a fluorescent dye that can be added to the system to check for leaks, and it will have instructions for use on the can. If there's a bad enough leak, the system will have no pressure in it at all. Find one of the valve-stem-looking things and CAREFULLY (eye protection recommended) poke a pen in there to try to valve off pressure, and if there IS none, that's the problem.

5. Make sure the compressor is turning. Start the car, turn on the AC and look under the hood. The AC compressor is generally a pumplike thing off to one side with large rubber and steel hoses going to it. It will not have a filler cap on it, but will often have one or two things that look like the valve stems on a bike tire. The pulley on the front of the compressor exists as an outer pulley and an inner hub which turns when an electric clutch is engaged. If the AC is on and the blower is on, but the center of the pulley is not turning, then the compressor's clutch is not engaging. This could be a bad fuse, a wiring problem, a broken AC switch in your dash, or the system could be low on refrigerant (most systems have a low-pressure safety cutout that will disable the compressor if there isn't enough refrigerant in the system).

6. Look for other things that can go wrong: bad switches, bad fuses, broken wires, broken fan belt (preventing the pump from turning), or seal failure inside the compressor.

7. Feel for any cooling at all. If the system cools, but not much, it could just be low pressure, and you can top up the refrigerant. Most auto-supply stores will have a kit to refill a system, and it will come with instructions. Do not overfill!

Tips • If you suspect bad wiring, most compressors have a wire leading to the electric

clutch. Find the connector in the middle of that wire, and unplug it. Take a length of wire and run it from the compressor's wire to the plus (+) side of your battery. If you hear a loud CLACK, the electric clutch is fine and you should check the

car's wiring and fuses. If you get nothing, the electric clutch is bad and the compressor will have to be replaced. Ideally, if you can do this test while the car is running, you can see if the hub spins. Take care to keep fingers and loose clothes away from moving pulleys and belts. That would rule out a clutch that actuates properly but then slips so badly it won't generate pressure.

• If your system is empty and you're refilling it, and have access to a small vacuum pump (like what they'd use in a lab or shop), it's best to suck all the air out of the system before filling it. Air contains moisture, and moisture is bad in AC systems because it corrodes things.

• Your system will have a light oil in it. If you vent off any refrigerant, be prepared to wipe some oil off things nearby.

• Another possible replacement refrigerant is HC12a which is used quite a bit more in Europe. It performs better than R-134a or R12. It is more flammable. HC12a is more eco friendly than R12 or R134a. Venting HC12a is not believed to cause environmental damage. Must be ordered on the internet as local shops do not seem to stock it. The issue is that shops will not work on a car that has other regrigerants in it. Special equipment is needed for each type of refrigerant's recovery. Standard R12 or R134a is a safer choice.

Warnings • Be extremely cautious about converting your old R-12 system to R-134a. The R-

134a conversion kits sold at Auto Parts stores and even WalMart, are called "Black Death Kits" by some AC repairmen. Frequently, the new R-134a refrigerant will not circulate the R-12 oil and you will burn up your compressor. The R-12 mineral oil has chlorine contaminants that will destroy the R-134a PAG or POE special oil. The only way to reliably convert from R-12 to R-134a is to remove the compressor and flush out all the old oil with the new type of oil; then replace the old Receiver-Dryer or Accumulator with a new one; then flush out all the lines, the evaporator, and the condensor with special cleaner then vacuum to a steady vacuum; and finally charge with 70-80%, (by weight) of the original R-12 weight, with R-134a; and expect poorer cooling ability. It is much easier to keep the old R-12 system running with R-12 that is readily available via ebay.

• Venting refrigerant -- even R-134a -- is illegal in the United States, so act accordingly.

• NEVER connect refrigerant cans, oil or leak-detector cans to the "high pressure side" of the system. This is often marked with H or HIGH, or a red connector cap. Cans can explode, and that would hurt.

• Stay away from major leaks of refrigerant. As it vents it will get cold enough to freeze your skin.

• Look out for moving fan blades and fan belts! • HC12 is a hydrocarbon, usually some mix of butane or propane. It will explode

with an ignition source. Light up a cigarette if you have an evaporator leak and your car becomes a bomb. Professionals don't use it because of this very reason.

How to Fix a Broken Nissan Micra When you are having problems with your baby girl, this guide will give you all the information needed to fix her.

Steps 1. DON'T BREAK IT!! 2. DON'T CRASH IT!! 3. If you do don't panic, remain calm. 4. Limp home with whatever damage you've got. 5. Find out where your nearest scrapyard is located. 6. Go to the scrapyard as soon as possible and locate another Nissan micra. 7. take the parts of the scrapyard micra that you require. 8. Take the parts home and fit them to your car. 9. Revel in the 'brand new' feeling as you drive your NEW one of a kind micra

around.

Tips • Be A Safe & Careful Driver • Don't take on any street races you can't handle

Warnings • ALWAYS wear a seat-belt

Things You'll Need • A Nissan Micra • A Set of Useful Tools That preferably fit the cars sockets. • A Phone Book (to find a scrapyard) • A lift to the scrapyard • A Chinese man to do all the labour for you.

How to Fix a Flat Car Tire with Fix a Flat Ever get a flat at the worst time? Here's a way to patch a car tire with Fix-A-Flat.

Steps

1. First of all, always carry a can of Fix-a-Flat with you. 2. If the hole in the tire was to large for Fix-a-Flat to be effective, looked around the

roadway for a small tree branch. Pick up one that doesn't have any bark on it and is the right diameter for the hole in the tire.

3. Lubricate the stick with lots of saliva and force it into the hole about an inch. 4. Snap the stick off flush with the tire and put the remainder of the Fix-a-Flat in. It

should seal the hole and add enough air to last until you get to a gas station to fill the tire properly.

5. Later, before this method wears off (about a month or so) go to the tire store so a professional can fill the hole.

Tips • Be prepared. The basics for car tire repair can fit in a milk crate. Always carry a

spare tire as well. Learn how to change a flat tire.

Warnings • Tire blowouts are very dangerous and can lead to fatal accidents. Always drive

carefully.

Things You'll Need • One can of Fix-a-Flat • A tree or bush branch of suitable width

Fix a Head Gasket With Engine Block Sealer In Feb. 2005, my car had the classic signs of a broken head gasket: oil was milky tan (coolant in oil), coolant was milky tan (oil in radiator), leaking coolant/overheating, white steam from tailpipe, very rough idle. My mechanic had initially recommended trying a block sealer. A clerk at the auto parts store recommended KW Permanent Metallic Engine Block Sealer since he's seen it work before. When mechanic saw how bad symptoms had gotten, he did not think sealer would work but tried it anyway. The process begins by draining all anti-freeze from radiator. Then one adds the Sealer/water mixture and idles car for 1/2 hour after which all water/sealer is drained and car is allowed to dry for a day. We were amazed that the leak was gone and the car was running

ok...though I eventually had to get a new radiator since it was not circulating coolant freely.

In August 2005, coolant began leaking from head gasket area. This leak was caught early enough that oil had not yet turned milky tan and coolant was normal color. So I did the KW process myself and it worked again.

Cost of sealer: $7.50. Cost had head gasket been replaced: $800-1000+.

Car drives fine both on freeway and in town. If I have to add the sealer twice a year, it's way better than the cost of replacing the gasket and not having use of the car.

How to Fix a Low Beam Head Light Here's how to repair a headlight that does not turn on.

Steps 1. Check your fuses. The plastic panel covering the fuses should have a diagram

detailing what each fuse covers. If yours is missing, or unlabeled, check your owner's manual, or a Hanes(tm) or Chilton(tm) repair manual. Often if a headlight is not working, it is the result of a blown fuse. Fuses have a wire running through them that will melt when too much current is run through them. If the fuse is blown, the wire will be broken. If the fuse for the headlight you are working on has an intact wire, it is likely the problem lies elsewhere.

2. Swap the headlight for its twin. If your left headlight does not work, put the light from your right headlight in its place. If it works with the other headlight in place, your headlight bulb is dead, and needs to be replaced.

3. If this does not work, try using a voltmeter on the plug for the bad headlight. Turn on the ignition, and turn the headlight switch. If the voltmeter shows no current, then either your switch or the wiring leading to the headlight has gone bad.

4. If replacing your headlight switch does not solve the problem, then there is a break in the wiring leading to the headlight, and the wiring will need to be replaced.

Tips • Some models are known to have headlight switch failures (Mazda RX-7, Nissan

300ZX, among others). Check to see if there is a website where owners of your model of car can go for help from fellow owners (z31.com, rx7.com, etc). Sometimes they can be an invaluable resource.

Warnings • Be sure to use a voltmeter to test the current on your headlight switch before

replacing it. Some headlight switches can be expensive to replace, and frustrating if it turns out to be a bad wire, and not a bad switch.

Things You'll Need • Working headlight • Voltmeter • Tools to remove headlight (usually a Philips screwdriver, check owner's manual

or Haynes(tm) or Chilton(tm) manual for more information on your model)

How to Fix a Stereo System in a 94 Dodge Intrepid This depends on how confident you are of your repair capabilities...

Steps 1. Diagnose your capabilites. If you are willing to repair the vehicle, your first step

should be consulting a "Hayes" or "Chilton" Manual specific for your vehicle. This will show you the location and simple removal/installation instructions for all of your speakers.

2. Diagnose the system. Are the speakers in the vehicle the ones that came from the factory? If so this is likely the problem. If the speakers are aftermarket (installed by someone other than the dealer or factory) you may want to check the wire connections.

3. Assuming the speakers are factory items, you will want to replace them with aftermarket speakers. You can find speakers at many retailers and online stores. Look up your vehicle's speaker sizes in a guide or consult the teardown manual.

4. Following the instruction of your manual, remove the factory speakers and replace them with your new speakers. If the new speakers will not directly connect to the factory wiring, you will need to cut and strip to expose the wire. Install female quick connects that match the size of the male ends on the speaker. Do not simply tape the wire to the speaker, it will fall off over time and if you are doing the job you may as well do it right.

5. Throw away old paper cone speakers. This part is fun, as your frustration with the cracking and popping sound they used to make is replaced by the elegant sound of them hitting the bottom of the trash can.

Tips

• "Hayes" or "Chilton" Manuals are step-by-step guides that show you how to remove and replace just about anything on your car or truck. If you plan on working on your vehicle at all, purchase one or more books on the technical information of your vehicle. Factory Manuals are available through dealers for around $100, "Hayes" or "Chilton" Manuals are available at most automotive retailers for around $15.00.

Warnings • When removing interior panels to get to speakers, be careful not to break the

connectors. Using a thin flat-head screwdriver is okay, but if you plan on doing more interior work, purchase an interior panel puller. (Looks like a mini crow-bar)

How to Get Bug Splats off the Front of Your Car Here's a quick and paint-safe way to remove bug splats from the front of your car, and to make it easier to remove them the next time.

Steps 1. Soak the splats with Windex from a spray bottle. Wait about ten minutes. 2. Spray the splats with a hard stream of water from a hose. 3. Gently remove the tough ones with a wet terrycloth washcloth. 4. After they're gone, wash the front of the car as you normally would. 5. Coat the area with a liberal amount of spray-as-you-dry car wax ("Express Wax"

or similar). Polish as directed. 6. The above process should be much easier next time.

Tips • Don't allow bug splats to accumulate. They can permanently stain the paint. • Don't forget to remove the bug bodies from the radiator.

Warnings • Never use a dry cloth on auto paint. You can easily scratch the finish.

How to Get Your Car Problems Sorted if You Know Nothing About Cars A lot of people have a hard time getting mechanics to take them seriously when reporting car problems. Does your mechanic seem to talk over you, or try to convince you that you're imagining problems? Here's how to cut to the chase when your knowledge of cars is just about zilch.

Steps 1. Before you go in, call about the problem so that you can find out what kind of

questions they're likely to ask or what information they'll need from you when you take your car in for its service.

2. Ask the service manager when is the best time to bring your car in so that you can have an unhurried chat about your vehicle.

3. Go over the problems with him and give him a written report of the problems. 4. If he doesn't know what you are talking about, have him drive it around the block

so that he can acknowledge and understand your concerns. Make notes on your list in his technical-speak to make sure you're both on the same page.

5. Leave the list with him. 6. When you pick up your car, drive it around the block to check that all the

problems have been solved and bring it back straight away if any of the problems persist.

7. If your car is new and you have persistent problems that the service dealer cannot fix, call up the factory and arrange for their service department to look at it.

Tips • Agree on costs before you give the go ahead on any work. • Expect to pay some diagnostics charges before you can get a good quote for the

necessary repairs. • Ask to have your quote seperated into necessary, immediate repairs and other

maintenance recommended. Maintenance is important, but you want to seperate fixing the current problem from preventing future problems.

• Ask about the warranty on the repair BEFORE the repair is performed. • Do get a second opinion, or at least call a second shop to check the prices you are

being quoted at the first shop. • When getting a second opinion, going to a local College, University, or Technical

school, may be your best bet. Since they are using your car for training, they will rarely try to "upsell" you into things you don't need.

• Going to the local College, University, or Technical school, although cheap because you don't have to pay labor, may take longer than you would like to wait. (They also rarely do regular maintenance work, to not steal away your business from local auto-shops).

• If you can, get someone who knows cars to come with you to the shop. The service advisor or mechanic will likely appreciate the help when you are explaining your problem(s) and when they are explaining the repairs back to you.

• If a mechanic sees that you don't know what you're talking about (or assumes it because you're a woman), they might try to rip you off at an unreputable garage.

• If your service advisor or mechanic cannot explain the repairs in a way you can understand, leave, and go to someone else. For the service advisor, this is the most important part of their job!

• Many car owners feel like the statement "we were unable to duplicate your concern" means the same thing as "we think you are crazy" or "we would rather be doing nothing than work on your car." This is simply not the case with a quality repair facility. Repair facilities rely on finding your problem in order to make a living. Sometimes, "we were unable to duplicate your concern" means they spent some time trying to get it to do as you described and were unable to do so.

Warnings • Do not take your frustrations out on the service manager. They did not build or

break your car. They are trying to help you get your car fixed! • Hopping from car dealer to car dealer hoping to find a miracle "cure" can be

counter productive, sometimes it's better to stick with a team who knows your car's history. If you have had your car to more than one mechanic, be sure to provide as much history as possible to your current mechanic, including copies of your previous work orders if possible.

• Remember that the mechanic who quotes you the cheapest price for a particular repair may not be the best. There can be huge differences in the quality of parts being used and in the warranty provisions for the repair.

How to Get Your Car Problems Sorted if You Know Nothing About Cars A lot of people have a hard time getting mechanics to take them seriously when reporting car problems. Does your mechanic seem to talk over you, or try to convince you that you're imagining problems? Here's how to cut to the chase when your knowledge of cars is just about zilch.

Steps

1. Before you go in, call about the problem so that you can find out what kind of questions they're likely to ask or what information they'll need from you when you take your car in for its service.

2. Ask the service manager when is the best time to bring your car in so that you can have an unhurried chat about your vehicle.

3. Go over the problems with him and give him a written report of the problems. 4. If he doesn't know what you are talking about, have him drive it around the block

so that he can acknowledge and understand your concerns. Make notes on your list in his technical-speak to make sure you're both on the same page.

5. Leave the list with him. 6. When you pick up your car, drive it around the block to check that all the

problems have been solved and bring it back straight away if any of the problems persist.

7. If your car is new and you have persistent problems that the service dealer cannot fix, call up the factory and arrange for their service department to look at it.

Tips • Agree on costs before you give the go ahead on any work. • Expect to pay some diagnostics charges before you can get a good quote for the

necessary repairs. • Ask to have your quote seperated into necessary, immediate repairs and other

maintenance recommended. Maintenance is important, but you want to seperate fixing the current problem from preventing future problems.

• Ask about the warranty on the repair BEFORE the repair is performed. • Do get a second opinion, or at least call a second shop to check the prices you are

being quoted at the first shop. • When getting a second opinion, going to a local College, University, or Technical

school, may be your best bet. Since they are using your car for training, they will rarely try to "upsell" you into things you don't need.

• Going to the local College, University, or Technical school, although cheap because you don't have to pay labor, may take longer than you would like to wait. (They also rarely do regular maintenance work, to not steal away your business from local auto-shops).

• If you can, get someone who knows cars to come with you to the shop. The service advisor or mechanic will likely appreciate the help when you are explaining your problem(s) and when they are explaining the repairs back to you.

• If a mechanic sees that you don't know what you're talking about (or assumes it because you're a woman), they might try to rip you off at an unreputable garage.

• If your service advisor or mechanic cannot explain the repairs in a way you can understand, leave, and go to someone else. For the service advisor, this is the most important part of their job!

• Many car owners feel like the statement "we were unable to duplicate your concern" means the same thing as "we think you are crazy" or "we would rather be doing nothing than work on your car." This is simply not the case with a quality repair facility. Repair facilities rely on finding your problem in order to

make a living. Sometimes, "we were unable to duplicate your concern" means they spent some time trying to get it to do as you described and were unable to do so.

Warnings • Do not take your frustrations out on the service manager. They did not build or

break your car. They are trying to help you get your car fixed! • Hopping from car dealer to car dealer hoping to find a miracle "cure" can be

counter productive, sometimes it's better to stick with a team who knows your car's history. If you have had your car to more than one mechanic, be sure to provide as much history as possible to your current mechanic, including copies of your previous work orders if possible.

• Remember that the mechanic who quotes you the cheapest price for a particular repair may not be the best. There can be huge differences in the quality of parts being used and in the warranty provisions for the repair.

How to Get the Dash off of a 1998 Pontiac Grand Prix It's easy. All you need is a Phillips screwdriver.

Steps 1. Under the steering wheel, down near the pedals, locate the 2 screws you need to

take out. You may have to lay down on the floor and look up. 2. Unscrew those two screws. 3. Sit in the driver's seat, grab the area where you just took the screws out, and pull

towards you. It is only held on by clips. 4. Next, you can pull off the other piece that covers the gauges and stereo. That

whole thing is held on by clips only. Don't lose the clips.

Tips • If you have fog lights, you have to make sure you pull the top panel out only a

couple of inches, then unplug the fog light switch from behind it. After doing so, you can pull the rest off.

• The top piece is much easier to get off if you move the steering wheel as low as it can go.

• Be sure not to lose the clips.

Warnings

• If something isn't coming off, don't keep pulling. Figure out where it is being held up and focus the pulling with both hands just in that area. Most likely, it is just a tight clip.

How to Getting the Dash off of a 1998 Pontiac Grand Prix It's easy, all you need is a Phillips screwdriver.

Steps 1. Under the steering wheel, down almost near the pedals, locate the 2 screws you

need to take out. You pretty much have to lay down on the floor and look up. 2. Unscrew those two screws. 3. Sit in the driver's seat, grab the area where you just took the screws out and pull

towards you. It is only held on by clips. 4. After that is off, you can pull off the other piece that covers the gauges and stereo.

That whole thing is held on by clips only. Don't loose the clips.

Tips • If you have fog lights, you have to make sure you pull the top panel out only a

couple of inches, then unplug the fog light switch from behind it, the pull the rest off.

• The top piece is much easier to get off if you move the steering wheel as low as it can go.

• Be sure not to lose the clipsl

Warnings • If something isn't coming off, don't keep pulling, figure out where it is being held

up and focus the pulling with both hands just in that area because most likely it is just a clip that is on tight.

How to Inspect Your Suspension System This is a guide to understanding the shimmy and shake of your car. If you suspect your suspension or tires have a problem and you feel inclined to tackle the cause, this guide will help you through how to identify and fix some common problems.

Steps 1. Get into the car and drive. Turn the radio down and listen to the car. A noise may

lead you in the right direction and show you where to start your search. A roaring sound may indicate a stuck bearing or a stuck brake shoe. Rattling on a bump may result from a dry bearing or a loose suspension part (which may be simple to tighten up on your own, provided that torque specifications are followed). A "clunk" may be a sign of your suspension needing grease, a bad ball joint, or a bad strut.

2. Try to really "feel" the car. A vibration in your steering wheel suggests a problem in the front of the car (most likely in the steering linkage). It may be a tie rod end or a bushing in the car's control arms. Seat vibration suggests a problem in the back of the car. It may be a wheel bearing or a runout condition in a tire.

3. Once you think you know where the problem is, park the car and let it cool. Grab your gloves and safety glasses. If you choose to lift the vehicle, put the car on a flat surface and use the proper supports. NEVER rely on the jack alone to support your vehicle, and never use bricks or lumber to hold your vehicle up. Use proper jack stands. Now you can get under your vehicle in the suspect area and get to work.

4. Be sure to know what you are looking at. Many suspension parts can be diagnosed by grabbing or rotating the part. For example, the tie rod ends, the Pitman arm, the idler arm, and other parts of the steering linkage. As for wheel bearings, bushings, and tires, you will need to have the wheels off the ground.

5. Tires are frequently the main culprit in these "not-so-good vibrations", due to different degrees of tire runout (such as the tire being shaped liked an egg, or the tire having a bulge effect in the side). With the tire off of the ground, spin the wheel and look at it head on. You may be able to see that the tire shows the above symptoms. However, you cannot always see this with the naked eye. While you have the tire in the air, grip the top and bottom of the tire. Wiggle the tire back and forth. If the tire shows signs of play, you have bad (or dry) bearings, or a bad tie rod end. You may also want to check to see that the lug nuts are not loose.

6. If you can't find anything through this basic inspection, you may need to take your car to a professional mechanic, where the proper diagnostic tools can be used.

Tips • There should be no detectable play in any part of your suspension system. Finding

this usually indicates a problem. • On cars without rack and pinion steering, the suspension should be greased every

time your vehicle has the tires changed or rotated, or every 10,000 - 15,000 miles.

Warnings

• Suspension parts are generally very dirty, and they can be extremely hot. Always allow the vehicle to cool down for at least 4 hours before attempting an inspection.

• Any suspected tire or suspension problem should be looked at right away. It could render the vehicle uncontrollable or unusable.

How to Install a Water Pump on a 1994 Pontiac Grand Am 2 4 Liter This is a quick guide on how to install a water pump on a 1994 Pontiac Grand AM 2.4 liter. I am not a mechanic, and the only experience I have with this is that I successfully installed a water pump on my own 1994 Pontiac Grand Am a week before writing this.

Steps 1. First you will need to drain all the coolent from the engine. Most likely, your old

water pump has failed and most of the coolent has already leaked out, so there might not be much coolent in the pump. Be sure to dispose of the old coolent properly, as it is poisonous and could be lethal to unsuspecting animals.

2. Next we will be working on removing the exhaust manifold, since the water pump is located right below it. On the manifold there is a heat cover along with an oxygen sensor. Remove both the heat cover and the oxygen sensor.

3. There are 10 bolts connecting the exhaust manifold to the engine; on my car, they are 15mm. 9 of the bolts you can reach from the top of the car that connects the manifold to the block. Remove these 9 bolts. We will get to the tenth in a couple more steps.

4. Disconnect the exhaust pipe from the exhaust manifold. You will need to jack up the car to do this. Once underneath the car, you will see two bolts connecting the pipe to the manifold. These bolts have springs on them (I think it's to ensure consistent tension). You will need to loosen one a couple of turns and then loosen the other a couple of turns, switching back and forth between the bolts until you get them out. By now, the pipe should be free from the manifold and you should be able to pull it back and down to disengage it from the manifold. There will be a little ring spacer between the manifold, and the pipe should fall free when you do this so watch your head.

5. Next you will need to take off the last bolt. You will be able to see it from under the car: It will be directly under the spot where the pipe and manifold join. (This bolt gave me a lot of problems when I tried to remove it. It was seized on and I could not find a way to get a cheater bar on. My friend brought over a 1/2" break-over bar and w/ some penetrating oil, we were able to break it free. I got at it from the top of the car since I could get more leverage there than from underneath. Hopefully, though, you will not experience so many problems.)

6. After you have removed the last bolt, the manifold should be free, so take that puppy out of there. You're now to the easy part.

7. You should be able to see the waterpump housing, it's located on the lefthand side of the engine in the back. The cover will have two bolts going into the block of the engine, two going down to the where the thermostat is mounted, and 5 going to where the water pump is mounted. These were all 10mm bolts on my car, if I remember correctly. Just loosen them, and the housing should come free; the housing also has a hose coming out of the front of it that runs underneath the exhaust manifold to the other side of the engine. I left this connected but that was a bad idea because I bent it to get the housing out of the way and put a hole in the pipe, so the safe bet would be to just disconnect the hose and take the whole housing out.

8. Now you should see the water pump. It will have 4 bolts connecting it to the engine. Take these out and it should slide right out of there.

9. Next you will want to clean off the old gasket and the waterpump cover. Take your time and make sure you get them clean.

10. Apply sealer onto the gasket and then put the gaskets on. Also, while you have it all apart, I would suggest replacing the thermostat.

11. Now just start putting everything back together. I applied bolt grease on all the bolts before reinserting them, so in case the water pump broke again, I wouldn't have to struggle w/ seized bolts. Also there are some torque species for the bolts that connect the water pump to the engine and the bolts for the housing, but since I don't have a torque wrench I didn't worry too much about them. I can't remember what they were.

12. Before putting the manifold back on, I would suggest you put some water into the radiator to make sure you don't have any leaks. I made the mistake of not checking, and had to take it all off again. If everything checks out okay, then put the rest of it back together.

13. Grab a beer.

Tips • This is pretty complicated, well at least it was for me. If you are not a mechanic at

all, you might consider taking it to a shop, but for what they quoted me at the shop, I decided to do it myself.

• At the very least you should get a book to help you with this. The book I used didn't have very detailed instructions but did have some pictures, and a picture is worth a thousand words.

How to Install a Wood Dash Kit Installation of aftermarket dash kits including but not limited to wood, carbon fiber and aluminum dash trim.

Steps 1. Check Fit and Alignment 2. Clean surface with alcohol wipes. 3. Carefully check fit of each dash piece to ensure proper alignment. Do not remove

red backing at this time. 4. Use Alcohol Pad to wipe surface clean. The surface must be free of all debris and

oils(armor all,etc) for the kit to adhere properly. 5. Carefully apply adhesion promoter. (included) Only apply to areas to be covered

with kit. 6. For larger pieces carefully position dash piece in plate. Carefully pull back top

half and remove red liner work from middle back to top then carefully remove red liner and continue with middle to bottom. (For small pieces you can remove entire red liner)

7. To complete installation firmly press dash into position and hold momentarily. 8. After kit is installed use a clean soft cloth and wipe(polish) to finish.

How to Know when Your Car Tires Need Replacing The performance of your car tires is critical to the safety, performance and efficiency of your vehicle. Most tires are designed to provide similar performance throughout their lives. However, at some point they start to lose performance in terms of their traction and braking ability. This article will help you decide if it is time to start shopping for a new set of tires.

Steps 1. Take a U.S. penny and hold it between two fingers so that Lincoln's head is

pointing up. 2. Insert Lincoln's head (the penny) in the grooves between the tire treads. 3. If you can see the top of Lincoln's head, replace the tires immediately. 4. If Lincoln's hair on the top of his head is partially visible it is time to go shopping

for tires. 5. If you cannot see the hair on the top of his head (IE. the coin is inserted enough

that the tire tread is at least as deep as Lincoln's forehead), your tires do not need replacing yet.

Tips • Tires do not wear perfectly evenly so be sure and insert the coin at several points

from the outside to the inside of your tires. Tires generally wear more on the inside but over-inflated tires will wear more in the middle.

• Test all of your tires and if possible, replace them all at the same time. Mismatched tires will not provide the same safety, performance and efficiency as a matched pair will.

How to Loosen Hinges on a Chevrolet Here are some suggestions for loosening the hinges on a chevrolet. There is no need to drill, just soak and let the rust penetrant and inhibitor loosen it for you.

Steps 1. Buy spray lubricant at a GM parts counter. Get GM rust penetrant and inhibitor

heat valve lubricant #1052627. 2. Soak hinge in the lubricant on the inside and outside of the door. 3. Leave to soak for a while. 4. Work door open/closed. 5. Repeat steps 2,3 and 4. Soon the door will move freely.

Tips • Keep penetrant off of paint as much as possible.

Warnings • Do not drill out the hinge.

How to Understand the Basics of Car Maintenance This article was written for the industrial maintenance technician, but can be applied equally to the family car. Actually, more correctly, the subject is the three phases of maintenance.

You may have heard it said, "if it ain't broke, don't fix it." That is the beginning of many problems. Phases one and two of maintenance require "fixing" what isn't broken.

Steps

1. The most obvious phase of maintenance is the repair function. Very simply stated, this means, "if it breaks, fix it." This is actually the third phase and means exactly what it says. It is a last resort and should arise only at infrequent intervals.

2. Phase one is systematic daily maintenance. The machine operator is usually responsible for this part. He/she simply cleans the equipment, observing anything out of the ordinary and reporting it to the maintenance department. This allows replacement of parts about to malfunction thus preventing chaining of problems.

3. Phase two is the regularly scheduled maintenance to include changing of fluids, thorough cleaning of parts not normally seen by the operator and a more detailed inspection for parts about to malfunction. This would include parts that are bent or broken, to include any possible cracks, obvious wear and signs of lack of lubrication.

4. It can readily be seen that proper performance of phases one and two will greatly reduce the occurrence of phase three, breakdown repair.

5. The greatest incentive for performing phases one and two regularly is that machine breakdown will invariably occur when the machine is used, and most often when it is being used most heavily. A machine that is idle simply doesn't break down.

How to Understand Compression and Power Systems in Small Engines Every engine ever made (including your lawnmower engine) requires 3 things: Ignition, which is a source of spark controlled by timing, compression, which means that air must be compressed to create rotation, and carburetion, which involves mixing fuel and air in the proper ratio for combustion.

An internal combustion engine is nothing more than an air pump. Torque and horsepower are a function of how much air is pushed through the cylinders. The more air, the greater the output of power.

Steps 1. Understand the basic function of the engine. The engine is an air pump. The

more air, the more power. 2. Become familiar with how compression works. The engine has a stroke, which

is the travel of the piston up and down the cylinder. The amount of room in that cylinder is described in terms of cubic inches (or centimeters) with the piston at the bottom of the cylinder. For example, a 351 Ford has 350 cubic inches. The compression ratio is a comparison of the volume (with the piston at the bottom) and the space left with the piston at the top of its stroke. Most lawnmowers are

low compression engines, with ratios of 8:1 or less. This is why they run well on cheap gas (87 octane).

3. Diagnosing problems: If you have a compression problem, the engine won't run (in 99% of cases). The best indicator of low compression is the engine pulling through too easily. If you hit the starter and the engine spins like crazy (unusually fast), you will need to check the compression with a tester. This is a simple air gauge that screws into the spark plug hole and traps the air inside as the piston runs up and down. If you're getting less than 80 psi, you've got a problem. The most common causes are a blown head gasket, or a stuck or bent valve.

Tips • The engine is a pump. It must have compression to run and produce power. • The carburetor is a mixing chamber for air and fuel. • The ignition is controlled by the flywheel, key, and coil (properly timed to the

engine). • Your fuel has got to be clean and fresh. Fuel begins to lose its octane in

approximately 90 days.

Warnings • Disconnect the battery before beginning any engine work!

How to Troubleshoot a Small Engine Problem Got a small engine that doesnt want to run? Before you spend lots of money at a mechanic, see if you can find out the problem for yourself.

Steps 1. Most engines that will not crank or run well need a spark plug. This can be

purchased at the local hardware store along with a wrench. Just ask! 2. If the spark plug doesn't help, check the air filter. If the engine can't breathe, it

can't run! 3. An engine needs clean fresh fuel. This fuel needs to be free from water and

debris. 4. Replace the spark plug wires, and consider replacing the cap and rotor (if your car

has one). These carry the electricity to your spark plugs, and if they've corroded or failed your plugs will not work. If you are unsure if your car has a rotor or cap, ask at a shop!

5. If new spark plugs or a new filter doesn't fix your engine, crank it over a few times (or run it for the short time it will run), and then pull your spark plugs and look at them. A black or sooty plug indicates the cylinder it is in is running too rich (leaking fuel injector or plug not firing well). A white and ash-covered plug can indicate the cylinder is running too hot (sticking fuel injector, wrong spark plug). If the plug does not "look normal", but you are unsure what it means, take the plug into a shop and ask! They should be happy to help.

Tips • Don't be afraid to ask as many questions as possible to answer your questions. A

repair man will not just divulge advice considering he gets paid for what he knows. Would you tell some kid in a greasy shirt how to set up a wireless internet connection knowing you could make hundreds connecting it up for him or her?

• Often automotive supply shops can be good sources for advice, as many owners of such shops either worked in or owned a repair shop at one point in time, and stand to lose nothing by sharing information.

Warnings • Always thread a spark plug by hand and tighten no more than 1-1/2 turns with a

wrench. • Always remove and replace spark plugs after the engine has cooled. Some

engines use aluminum threading for the spark plug sockets, which is easily destroyed if force is applied when hot.

Things You'll Need • Nitrile gloves (unless you have tough skin). • 3/8 ratchet and deep well socket for spark plug (the socket type may vary on the

make/model of your car, if you don't know, ask!). • phillips, flat or torx driver depending on model. (ask!)

How to Tune up Your Battery In this article, you will learn how to maintain and tune up your car battery.

Steps 1. Make sure it's secure. An often neglected component of a battery is its holddown

straps. An unsecured battery is an accident waiting to happen. The bouncing of a vehicle, especially a tractor over a plowed field, can cause a battery to scoot around in its housing and possibly short out against another metal component

causing a fire. If not that, it can certainly break a terminal, cable, or case. Purchase a battery hold down kit and install it. It is cheap insurance against car, tractor, truck damage and will increase the life span of the battery.

2. Invest in a battery terminal remover tool. This cool tool looks like a small gear puller with clamps. After the terminal bolt is loosened, the puller makes removal of the terminal an easy job. Don't screw a stuck terminal back and forth or use a screwdriver to try and pry it off. You can inadvertently crack the battery case or break the seal between the case and the protruding terminal. A puller is cheap, easy to use, and does the job correctly.

3. Once the terminal end is removed, inspect the mating ends for corrosion, pits or cracks. A battery terminal cleaner works great for removing corrosion build up. This tool has two wire brush ends; one male, the other female. Use it to brush the ends until they shine. Sometimes a terminal end will have a hard blackish coating on it. This lead oxidation stops the electricity from flowing and creates excessive heat at the connection. It won't always come off with the wire brush so you may have to use a small file. Make sure to rotate the file around the terminal as you go so you won't create a lot of flat spots. Don't remove too much material, then tidy up the terminal with the brush. If the bolt is corroded, replace with a new one.

4. After removing the hold down strap and terminal ends, remove the battery from the vehicule and place on a plastic box or covering.

5. Hose down the top of the battery and brush off the accumulated debris. 6. Take a towel and dry off the entire casing. 7. Remove the filler ports and check the levels. Place on charger and fill

accordingly. 8. Do a load test. With the battery installed in the vehicle, attach a voltmeter to the

battery terminals. Ground the coil to keep the engine from starting and crank the motor over for 15 seconds. If the battery voltage stays above 9.6 volts, then the battery is in a reasonable state of charge. Below that amount indicates a shorted cell or a lowered capacity due to the battery is heavly sulfated harming its useful life. Treat it with ResureX additive and install the MAXI-Life Pulse you could recover from the junk 80% of discarded ones. (BCI source)

9. When reinstalling a used or new battery, use a terminal conditioner on the cable and terminal ends. The conditioner comes in a spray can and goes on like a red paint. The coating retards battery acid corrosion and lead oxidation and will lengthen the time between cleanings. One can also install felt pads onto the battery posts which have been saturated with baking soda. These also tend to retard acid corrosion. The negative cable has the smaller end and goes to the corresponding terminal.

10. Reinstall the hold down brackets or straps making sure not to overtighten which can cause warpage and/or breakage of the battery case.

Tips • Excessive corrosion on the cable terminal can be removed by submersing the end

in a coffee can of water and baking soda solution for a while. Remove, dry and then wire brush the mating parts.

• Terminal ends that are pitted, cracked, or missing due to acid corrosion, should be replaced. It is best, in the long run, to replace the entire cable rather than merely an end. If the terminal end needs replacing, the chances are good that the reason for damage has made its way up the cable under the insulation where it can't be seen. Examples could be unseen corrosion damage, copper strands that have been too hot from resistance and have burned themselves into the insulation, or have been heat damaged, or have internal strand breakage.

• If a battery is to be removed for the winter months, take a few moments to ensure that it will be in good condition when spring comes. Clean the casing and dry with a towel. Clean the terminal posts and check the electrolyte level. Place the battery off of the floor, preferably on a wooden bench or shelf.. Place a trickle charger on the battery to bring it up to charge always with our electronical device MAXI-Life Pulse attached across the negative & positive terminals. Some chargers have an automatic shutoff switch that will shut the unit off when the battery comes up to a full charge, and then turn it back on when the charge falls below a predetermined level. This type of charger can be left on all the time. (Float mode).Other fero-resonant chargers must be removed to prevent overcharging. When the battery is fully charged store it in a cool, dry location out of the way of kicking feet or falling tools. A light coating of petroleum jelly on the posts will prevent any lead reaction to the elements. When spring comes the battery should be ready to go back to work for your tractor. Boat,Golf cart etc.

Warnings • Don't drive the terminal ends onto the posts using a hammer. The jarring action

may damage the internal connections of the battery. Instead, use a terminal spreader.

• Don't overtighten the terminal bolts as you can cause stress cracks on the ends.

How to Take Care of Automotive Batteries It's very important not to let corrosion set it in on your battery terminals. Once corrosion sets in, your car will randomly fail to start due to electrical contact being lost between battery and cable. Especially common with GM vehicles. Read on for more details.

Steps 1. Go to the auto parts store, and acquire some battery terminal goo, the stuff that

prevents corrosion. Usually comes with a new battery. Better yet, you can purchase some battery corrosion prevention spray.. does the same thing, easier to apply.

2. Remove any rubber or plastic covers off of the battery terminals. Not the posts on top, but the terminals on the side that the cables bolt on to.

3. Do you see any blue or white powder/corrosion forming anywhere? If no, put the covers back on and crack open a beer, you're done.

4. If yes, you see corrosion, then you've got work to do. Remove both battery terminals with a socket wrench. Please watch what you're doing here. Don't short circuit the red terminal to any metal part of the engine or your going to be sorry. Just be cool when you ratchet the wrench back and forth.

5. Get a wire brush and scrape off all the corrosion crud from the bolt, the cable assembly and the battery terminal itself. Get inside the threads of the battery female connector. Make real sure you get all the crud off the cable assy, including the connectors. I have had to cut off the rubber insulation so that I could get all the corrosion off. Just make sure to cut the rubber so that you can put it back on later. Tip - pour boiling water over the corrosion before starting any other cleaning - it will dissolve much of the deposits and wash them away. Wash down thoroughly with plenty of cold water afterwards.

6. Check again to make sure you've got every last bit of corrosion brushed off. The corrosion is battery acid that has reacted with the air and metal. If you don't get it off, it continues to react and cause problems. In fact some say it will slide down the cable assy insulation and force you to replace the whole assy at considerable cost.

7. Once everything's hunky dory and spotless, then spread the goo or spray all the mating surfaces completely.

8. Now you're ready to put it all together. Don't over tighten and strip the battery threads... it's only soft lead after all. Put the positive (red) on first, then the negative (black).

Tips • You may have to reset your clocks and radio presets, since all battery power was

lost. • If your car doesn't start after running fine just hours before, it may be this

problem. Usually it happens with an older car with an older battery. Just putting in a new battery without cleaning the cable connectors corrosion sets you up for the same exact problem all over again! That corroded material just keeps eating away forever, if you don't get it all. Don't be lazy, do it right, and you should be good to go. A good dusting with baking soda occasionally, neutrulizes the battery acid. The red and green felt washers from the auto part store for post batteries are useful and help ID the polarity better.

Warnings • Watch out with sparks when attaching the positive terminal back... if you have an

old battery that is leaking hydrogen gas from the cells, then a spark might cause a little flash-bang, and that won't do your eyebrows any good. Make sure there is

plenty of ventilation, and as always wear good eye protection during the whole job.

• Do not wear a watch especially with a metal strap or bracelet while working on a battery. Shorting the positive terminal to ground or chassis anywhere with your watch strap will cause it to become red hot very quickly and badly burn your wrist at the very least. This applies also to any other metal jewelry such as rings etc.

• Do not touch the white powder or corrosion with bare hands. The battery acid can and will start eating through your skin. If you do touch it be sure to wash your hands right away - Once you feel it, it's often too late

How to Switch to Synthetic Motor Oil Using the proper synthetic oil and the best filters will increase your mileage and make all of your vehicles last longer. Research by independent labs (not the manufacturer) will give you the truth about wear and the usable life of gear and motor oils.

Steps 1. You must start with a vehicle that is in good usable condition. Nothing can cure a

worn out or abused vehicle. 2. Be sure that you have done the simple things like having the correct size tires at

the correct air pressure (the best mileage will be with the tires at their maximum recommended pressure). In winter, you may want to use less pressure for better traction (I believe this has been disproven. Always use manufacturers recommended tire pressure).

3. Research the synthetic oil industry. Independent lab tests give unbiased reports. 4. After determining the best synthetic oil, air filter, and oil filter for your vehicle,

you will need to make the changes yourself or have someone that you trust or even a shop make the change over to synthetics.

5. Synthetics allow for extended oil changes (12, 25, even several hundred thousand (100,000 +) miles between changes using bypass oil filter systems). Proper filters and the characteristics of the oil allow for this. Proper monitoring has shown that over 400,000 miles on an oil change is very possible.

6. Synthetics reduce friction so much that just changing the oil has raised the idle rpm ina 7.3 power stroke diesel by nearly 300 RPM'S.

7. Changing the oil at longer intervals means less money paid out, so the synthetics will pay for themselves.

8. The reduced friction means less wear and less wear means longer engine and part life.

9. The end result of using the best synthetic oils and the best filters are better mileage, longer lasting vehicles, and less money going out of your budget in the overall picture. The synthetics cost more upfront, but they actually save money in the long run.

Tips • The larger and more expensive a vehicle you drive, the more synthetics can help

you save money. • The more miles you drive, the more that the bypass filter system will make sense

and cents for you. • Even though the synthetics are expensive there are ways to obtain them for less if

you do a little research.

Warnings • Beware of chain store or store brand oils when it comes to synthetics. The

"Marts" get bids for the cheapest way to make items. The result is that the manufacturer cuts corners and leaves out additives to "get the deal" at the cheaper price. That leaves you,the consumer,with a cheaper and more inferior product. Again, look at the independent studies for the real truth.

Things You'll Need • If you choose to change the oil yourself, you need to know how much oil is

needed for your vehicle. • You will need a wrench or socket to fit the drain plug and possibly a filter wrench

for the oil filter. • If you go for the bypass system, you will need to drill mounting holes, have some

basic knowledge of using tools, and a socket and wrench set. Someone to help you would save a lot of trouble. Just review the instructions before draining the oil. If you need to get additional parts and only have the one vehicle, well, you see the problem.

How to Switch to Synthetic Motor Oil Using the proper synthetic oil and the best filters will increase your mileage and make all of your vehicles last longer. Research by independent labs (not the manufacturer) will give you the truth about wear and the usable life of gear and motor oils.

Steps 1. You must start with a vehicle that is in good usable condition. Nothing can cure a

worn out or abused vehicle. 2. Be sure that you have done the simple things like having the correct size tires at

the correct air pressure (the best mileage will be with the tires at their maximum recommended pressure). In winter, you may want to use less pressure for better

traction (I believe this has been disproven. Always use manufacturers recommended tire pressure).

3. Research the synthetic oil industry. Independent lab tests give unbiased reports. 4. After determining the best synthetic oil, air filter, and oil filter for your vehicle,

you will need to make the changes yourself or have someone that you trust or even a shop make the change over to synthetics.

5. Synthetics allow for extended oil changes (12, 25, even several hundred thousand (100,000 +) miles between changes using bypass oil filter systems). Proper filters and the characteristics of the oil allow for this. Proper monitoring has shown that over 400,000 miles on an oil change is very possible.

6. Synthetics reduce friction so much that just changing the oil has raised the idle rpm ina 7.3 power stroke diesel by nearly 300 RPM'S.

7. Changing the oil at longer intervals means less money paid out, so the synthetics will pay for themselves.

8. The reduced friction means less wear and less wear means longer engine and part life.

9. The end result of using the best synthetic oils and the best filters are better mileage, longer lasting vehicles, and less money going out of your budget in the overall picture. The synthetics cost more upfront, but they actually save money in the long run.

Tips • The larger and more expensive a vehicle you drive, the more synthetics can help

you save money. • The more miles you drive, the more that the bypass filter system will make sense

and cents for you. • Even though the synthetics are expensive there are ways to obtain them for less if

you do a little research.

Warnings • Beware of chain store or store brand oils when it comes to synthetics. The

"Marts" get bids for the cheapest way to make items. The result is that the manufacturer cuts corners and leaves out additives to "get the deal" at the cheaper price. That leaves you,the consumer,with a cheaper and more inferior product. Again, look at the independent studies for the real truth.

Things You'll Need • If you choose to change the oil yourself, you need to know how much oil is

needed for your vehicle.

• You will need a wrench or socket to fit the drain plug and possibly a filter wrench for the oil filter.

• If you go for the bypass system, you will need to drill mounting holes, have some basic knowledge of using tools, and a socket and wrench set. Someone to help you would save a lot of trouble. Just review the instructions before draining the oil. If you need to get additional parts and only have the one vehicle, well, you see the problem

How to Stop an Engine from Overheating If your radiator is not working properly, heat can destroy your car. Here's how to cope with heat until you can repair your cooling system.

Steps 1. If you have the air-conditioning on, turn it off! The A/C makes the engine work a

little harder, which you want to avoid right now. 2. Flip the climate controls to vent, turn the heater all the way up, and turn the fan all

the way up. If this is summer, open all the car windows or you will roast (if you are sitting in traffic on a hot day, this is going to be hard for you). Try pointing your vents out toward the window. Also bring along a spray water bottle with cold water so you can spray your face if you feel too hot. Don't do this in heavy traffic or when it is dangerous for you. Why this works: The heater in most cars works by using extra heat from the engine to heat the incoming air. (This is why it always takes the heat a few minutes to "come up" in the winter.) So turning the heat on full-blast pulls as much heat as possible off the engine and blows it into the cabin of the car.

3. Turn off your engine, but only if you are sitting in traffic and not moving for more than a minute. Keep a lookout ahead for when the traffic will move and turn your engine on and put it in gear before that point. (This is a huge tip because as soon as your engine turns off the cooling system gets a break.)

4. Keep it steady in stop and go traffic. It is better to move at a steady slow pace than to go fast, stop, go fast stop, etc. (Generally people will not cut you off in stop and go traffic since everyone is stuck in the same situation.)

5. Pull over if you think your car will break down in stop and go traffic. Turn off the engine and wait for the traffic to start moving normally. This should only be used in extreme measures, like when the temperature gauge on your car is on the H. Once the traffic starts flowing again, it is better for you to drive faster than slower as more air will come in and cool your engine.

6. Take your car to a mechanic ASAP. While the above steps are good when you're in a pinch, they won't help in the long run, especially if your cooling system is shot.

Tips

• If your car does overheat and steam starts to come out from under your hood, you'll have to pull over. You can add coolant (or water if you don't have coolant) to the radiator, but be careful opening it. When you take the cap off, steam will pour out and scald you. Instead, place a towel over the cap and radiator, grip the cap through the towel, twist and pull away quickly. It is better to open the radiator cap while the engine is idling rather than turning it off. Do not turn the engine off to add water. If the cold water you are pouring in comes in contact with the very hot engine it will crack the block and it's then time to replace the engine! It ensures that no steam will pour out when you twist open the radiator cap because hot water is still circulated by the water pump.

• If your coolant is leaking somewhere, then you will have to continually replenish it. Pull into locations likely to have a garden hose that they won't mind you using. Churches are usually a good bet.

• If your car tends to run hot, make sure you use proper coolant/anti-freeze and not water in your radiator. Water has a lower boiling point, so your car will overheat and become inoperable more easily with water. In addition, coolant offers other protection to your car against rust and freezing.

• In extreme cases, the engine may continue running after you turn the key to off. This is because the engine is so hot that it is auto-igniting even without the electric spark. In this situation put on the handbrake and then put the car into gear - this will cause the engine to stall.

• If your engine is overheating due to excessive load (such as driving up a long, steep incline or pulling a heavy trailer) it is typically better to pull off to the side of the road, shift the transmission to neutral (or park) and rev the engine slightly (2500 to 3000 rpm). This will allow the cooling system to actively cool the engine while it is under no load and is more effective than shutting the engine off, which only allows heat to dissipate passively. However, if your engine is out of coolant then you should immediately turn the engine off and open the hood of the vehicle to allow the heat to dissipate.

• If you are in slow-moving traffic, you can pop your hood. It will stay closed on the safety catch, but open a small gap, allowing greater ventilation (you'll see cops and cab drivers do this in big cities on hot days). DON'T FORGET TO CLOSE YOUR HOOD IF YOU GET TO A FAST-MOVING HIGHWAY! You don't want the hood to suddenly pop up in front of you while you're going 70!

• Depending on why your car is overheating you might want to turn the air conditioning on. Some cars have electric fans. The fan is turned on by a computer, based on a reading from a temperature sensor. Sometimes this system will fail and not engage the fan. Some of these cars automatically turn the fan on when the air conditioning is turned on, overiding the failed components.

Warnings • Do not pour cold water onto the engine or radiator. This can cause casings to

crack. • This technique won't work with every car. Sometimes when you turn off an

overheating engine to also turn off the fan, and water pump. This is how how

coolant gets moved around the engine. If this process stops, you keep all the hot water inside the engine.

How to Retrofit Air Conditioning in Cars to New Refrigerant If A/C in your car no longer works, you can retrofit your air conditioning system to accept refrigerant currently available. Before you do this, make sure your A/C tries to turn on (clicks and runs, but does not get cold).

Steps 1. Skip to step 4 if your car is a '96 model or newer, If your car is a '95 model or

older, continue reading. Many GM models from '94 on are R134a and would fall under the '96 and newer category. To verify, look under the hood of the car for a label that will tell you what refrigerant the system uses.

2. Have the freon (R12) still in the system evacuated with a recovery machine by a licensed professional.

3. Buy a "dryer" at an auto parts store, and replace the original in your car. A sales rep in the store can tell you where the dryer is and how to change it out.

4. Replace the dryer. Remember to replace the "o" rings supplied with the new dryer.

5. Go to your nearest auto service center and ask them to vacuum down your A/C system (at a cost of approximately $5-15). This process removes atmosphere from the system.

6. Purchase an A/C retrofit kit for R-134a refrigerant ($30) at your local auto parts store. Also purchase enough refrigerant to fill your system (the sales rep can tell you how much you need). Do not forget to buy a can of "oil charge" for your A/C system. Failure to do so will sieze your compressor, necessitating a $500+ repair.

7. Explore using a substitute for R-12 systems. There are other refrigerants available that are superior to R-134 for use in older R-12 systems and may also be used in R-134 systems. In general, they are cheaper than R-134. However, be aware that some of these are based on flammable gases. Since your fuel system is also pressurized, that would be an equivalent or worse fire hazard.

8. Connect the kit to your car, referring to the supplied instructions. 9. Start the car and turn the A/C on full blast. Use the kit to add the oil charge first,

and then the refrigerant that your car needs. Be careful not to overfill. Note: To get the refrigerant to move from the can into the system, you can use a pitcher of warm water. Put the can right side up into the water and stir the water with it. The temperature difference will help force the freon into the system.

10. Keep the car running, and check to see if it produces nice cold air. If it's not really cold, you need to add more refrigerant.

Tips • It it illegal and harmful to the environment to release refrigerant into the air. • DO NOT forget to get your A/C system evacuated prior to adding new refrigerant.

R-12 refrigerant (freon) DOES NOT MIX with R-134a refrigerant (the new stuff). Failure to do so will cause the "black death syndrome" in which the conflicting refrigerants will turn into a black goo that clogs your entire A/C system, resulting in a $900 plus repair.

• DO NOT FORGET to REPLACE YOUR DRYER in cars '95 model year and older. Failure to do so will result in the "black death syndrome" as well.

• Follow instructions that come with your retrofit kit and you will be fine.

Warnings • Be careful to keep hands and tools away from moving parts and hot parts of your

engine. • It it illegal and harmful to the environment to release refrigerant into the air.

Things You'll Need • Adjustable wrench • Retrofit kit (allows you to connect to your A/C system and add refrigerant and oil

charge) • R134a refrigerant (explore using a substitute R-12) • Oil charge (Preferabley Ester Oil. Although PAG oil will work, some customers

report problems with PAG oil. They both cost the same. • New dryer ('95 model year and older)

How to Replace Starter in a 1998 Tacoma Save some money by doing your auto repairs yourself. These instructions are specifically for replacing the starter in a 1998 2.7L 4 cyl Toyota Tacoma.

Steps 1. Read through entire process, and consult repair manual if possible, to gain an

understanding of all of the steps required. Look carefully at the layout of the starter, engine, brake lines, etc, to determine what will be involved with replacing your starter.

2. Disconnect negative terminal on battery.

3. Remove the flexible rubber liner from the back of the wheel well on the side of the engine where the starter is located. This will give you better access to the starter.

4. Remove the plastic cap from the battery cable on the starter. Then, unscrew the nut that holds the cable onto the starter, and remove the cable.

5. Remove the other battery connector from the starter. 6. Unscrew the two bolts that hold the starter onto the engine. 7. Pull the starter forward to disconnect, then wiggle it out through the hole in the

wheel well. Set the old starter aside, you can usually return it to the parts store where you bought the new one.

8. Wiggle the new starter into the engine compartment in a similar fashion. 9. Insert the starter into the engine, make sure that the gears engage the flywheel,

and are not just resting on top. 10. Finger-tighten bolts to make sure they are threaded correctly, then tighten. The

repair manual suggests using a torque wrench to tighten them to 29 ft. lbs., be careful to not overtighten and break the bolt.

11. Attach the battery cable and battery connector (wires removed in steps 4 and 5). Then replace the plastic cap.

12. Replace the flexible rubber in the wheel well. 13. Reconnect the negative battery terminal and try starting your truck.

Tips • Removing the flexible rubber liner from the wheel well gives you much better

acces to the starter. I found that the top bolt is easiest to remove from the side of the truck, while the bottom bolt is easiest to remove from underneath.

• To remove the old starter from the engine compartment, it is necessary to bend one of the brake lines slightly, and turn the starter just the right way. If it isn't coming out, take a step back, then try to turn the starter in a new direction to wiggle it out.

Warnings • Make sure you disconnect the battery before doing any work on your engine that

involves electrical components

Things You'll Need • 12mm wrench • 14mm wrench • New Starter • 1-2 Hours

How to Replace Disc Brakes

Front brakes on all modern cars are disc brakes. The front brakes generally provide 80% of the stopping power, and so tend to wear faster than the rear. Replacing them - pads, rotors and calipers - is quite simple, and can save you a great deal of money. These instructions will include a full front brake replacement. Also, having a service manual for your vehicle will save your sanity, as well as time and money. If you only need pads and rotors, but not calipers, skip the steps for replacing calipers. Repeat the below steps for each side of the car as necessary.

Steps 1. Determine what parts and tools you'll need. If the front brakes are squealing

loudly, you'll need pads only. If the car shakes when braking, you'll need to have the rotors cut, or replace them. If the car pulls to one side while braking, but stays straight otherwise, you may need calipers.

2. Go to the parts store and buy more parts than you think you'll need. You can always return what you don't use, and if you get caught without something while the car is apart, you may not be able to go anywhere to buy anything.

3. Park the car in a clean, well-lighted place. Block the rear wheels with something heavy to prevent the car from rolling while it's jacked up. Apply the emergency brake (emergency brakes only use the rear, not the front). Give the car a good couple of shoves from side to side; if it's going to shift on the jackstands or fall off, better now than when you're partially under it with the wheels off.

4. Remove the front hubcaps and loosen the lug nuts before jacking the car up. If you skip this step, loosening the lugs may be very annoying, if not impossible.

5. Jack the car up with a floor jack and put it on jackstands. Make sure the jackstands are positioned under a solid part of the car - frame or subframe. Finish removing the wheels. Place the wheels under the car, just to the rear of the jackstands. In case the car slips off the stands, those wheels can prevent you from being caught under a falling car.

6. Make sure you have all the necessary tools. There are two bolts that hold the caliper to the pad bracket, and two bolts that hold the pad bracket to the steering knuckle. If you don't have the tools to remove these, now is the time to put the wheels back on and go to the hardware store. [You may need both SAE and Metric sizes of wrenches and sockets, as well as bleeder screw wrenches. Also, you may need a set of hex key wrenches or a hex bit socket set.]

7. Remove the caliper from the pad bracket. The pads may come out with the caliper, or stay in the bracket, depending on the car. Place the caliper on top of the steering knuckle, or hang it with a piece of clothes hanger wire or any other place where it won't be hanging from the brake hose.

8. Remove the pads and inspect them for wear. You may need to employ the large flat screwdriver to get the pads out. If either is down to the metal backing, you'll need to cut or replace the rotors. This is also a good time to compare the wear pattern of the left side brakes to the right side. If there is a vast difference, you'll need to replace the calipers.

9. Apply antisqueal paste to the backing of the new brake pads, but do not install them yet.

10. Inspect the brake rotors. If there are any grooves, or excessive glazing, remove them for cutting or replacement. Inspect the brake hoses. If they are leaking by the fittings or damaged, they'll need replacing - but that is outside the scope of this article. If you are only installing brake pads, skip to step 20.

11. Remove brake rotors. Unbolt the pad bracket from the steering knuckle. The bolts that hold this on tend to get frozen, so you may need to employ a hammer, breaker bar, Liquid Wrench or a torch to loosen them.

12. On most cars, the rotor is separate from the hub. Simply slide the rotor off of the studs. You may need to remove a set screw and/or use a rubber mallet to loosen the rotor. You may need an impact driver to remove a set screw. If the brake rotor and hub are one piece, remove the cotter pin and castle nut from the axle to allow removal.

13. To get the rotors cut, take them to a machine shop. Most auto parts stores have brake lathes or a machine shop. Call before starting your job to verify hours; most machine shops are only open until noon on Saturday and are closed on Sunday. Rotor/hub assemblies can be cut, but I would recommend just replacing them. Even though the replacement parts are expensive, you're replacing the hub and its bearings instead of putting the old hub and bearings back on the car. However, not all new rotor/hub assemblies include the bearings [although they usually install new races, so you can just "drop in" the new grease-packed bearings]. You may have to install them yourself, as well as pack them with grease. So a set of bearings may be a necessary purchase as well. [When applicable, this is also a good time to repack your front wheel bearings. Refer to your service manual or lubrication guide for this procedure. You'll need some new cotter pins and wheel bearing grease for this, as well as a pair of needle-nose pliers.]

14. Install the new or cut rotors the same way they came off. New rotors have a layer of oil on them to prevent rust while they're on the shelf. Clean this off with carb cleaner; it works better than brake cleaner in this case. Reattach the pad bracket. If you are not replacing calipers, skip to step 20.

15. Replacing calipers. Make sure the brake fluid reservoir is securely closed. Remove the bolt holding the brake hose to the caliper. This is a special hollow bolt that allows fluid to flow through it; don't lose it.

16. Drain the fluid from the caliper into a safe container for proper disposal. 17. The new caliper will come with two brass washers, rubber grommets for the slide

pins, pad retaining clips (if applicable), possibly new slide pins, and maybe that hollow bolt mentioned above. Make sure that the calipers are installed with the bleeder fittings/screws in the upper or top position. If you accidentally switch the left and right calipers and install them on the wrong side (easier to do than you think!), the bleeder fittings will be in a lower position, which will result in trapped air inside the caliper fluid chamber, which will make bleeding the brakes impossible to do. Remember, bleeder screws UP!

18. If you need to reuse the old slide pins, clean them with a wire wheel or brush. 19. Reattach the brake hose by putting a new brass or copper washer on each side of

the hose fitting, and the hollow bolt through. Reuse of the old washers, or failure

to put the new ones in the right place will cause the brakes to leak. Tighten the bolt firmly.

20. If you haven't done so yet, clean the caliper slide pins, and any place where the pads slide against the caliper or pad bracket with a wire brush. Apply brake lubricant to all of those locations.

21. Compress the caliper piston, if necessary. Take one of the old brake pads and place it in the caliper against the piston. Using the large C-clamp (usually an 8" to 10" size {inner measurement} will do), slowly and evenly compress the piston back into the caliper. Some brake fluid may come out of the reservoir at this point; watch out for drips if you're on the driver's side. Be careful, brake fluid will remove the paint from your vehicle!

22. Put the new pads in the caliper or bracket. You may need to employ the large flat screwdriver again, but this time be more careful so you don't destroy any of the pad clips.

23. Place the caliper back into the pad bracket, and bolt it in. If you have not replaced the calipers, skip to step 27.

24. Bleed the brakes. You'll need two people for this, and do one side at a time. Put the wheels back on the car to hold the rotor on straight, but do not let the car down from the jackstands yet.

25. Remove the rubber cover from the bleeder screw, and unscrew it about 1/4 turn, or just enough to loosen it. Attach an appropriate size clear or rubber hose to the bleeder screw with the other end immersed in brake fluid in a jar or can. This helps to avoid sucking air back into the bleeder screw.

26. Have your assistant slowly depress the brake pedal until it's at the floor. While the pedal is at the floor, close the bleeder screw. Have your assistant slowly lift the pedal. When the brake pedal is all the way up, open the bleeder screw. Repeat this process until you see brake fluid (without bubbles) coming out of the bleeder. Some brakes are gravity-bleed, and only require you to open the bleeder screw until you see the fluid, without working the brake pedal, but this procedure works in all cases. Make sure the brake fluid reservoir does not run empty, else you'll be introducing air into the brake system again and will have to bleed it all out.

27. Put the wheels back on. Tighten the lug nuts in an opposing fashion so the wheel goes on straight. Example: If you have five lugs, tighten them in a star pattern.

28. Check the brake fluid level and fill as necessary. 29. Sit in the driver's seat and push slowly on the brake pedal a few times. The first

time, the pedal may go down a ways, but the pedal should be high and firm after two or three times. This seats the pads against the rotors.

30. Check for leaks at the brake hoses if you've replaced the calipers. 31. Lower the car and perform a "mini" test drive, with wheel blocks situated a little

behind and in front of the vehicles front and rear tires to allow some movement to test the brakes. Otherwise you may find out the hard way that your brakes aren't working. During an actual test drive, make sure the car doesn't pull, that there are no funny clunking noises, and that the brakes are working correctly.

32. Retorque the lug nuts and put the hubcaps on.

33. Throw the old parts away, put your tools away and clean up. You're all done. Use a mechanics' hand cleaner, because brake dust contains asbestos, and brakes get really dirty.

Tips • Brake pads may contain asbestos, so don't use compressed air to clean out your

brakes or wheels before working on your car. Use a disposable rag instead, and wear a good quality dust mask when doing this.

• Always replace brakes in pairs. Pads on both sides, rotors on both sides, calipers on both sides.

• Keep your work area clean and organized, so you don't lose any tools or parts. Keep plenty of paper towels and rags handy. Also, remember to wear old clothes. Don't work in your suit, if possible.

• Even if you can get your rotors cut, buy new rotors the first time. That way, the next time you can take your old set in to be cut before you take the car apart.

• Disc brakes squeal by their nature. Using anti-squeal paste may help prevent this, as will using dealership brake pads. Cheap brake pads squeal more often, but the squealing of new brakes does not indicate improper installation or safety hazard.

• Use a little anti-sieze compound on bolts and fittings, such as around the inside where the rotor fits onto the hub, to make future removal easier. Don't use too much!

• Buy the best quality parts you can afford. You're already saving from not paying mechanic's labor charges, so splurge on the parts, for ricecakes!

• Use the jack from the trunk of the car if you must, but a small floor jack is much safer and not very expensive. Jack stands are good idea as well. Never work under a vehicle using just a jack! Always use jack stands!!!

• Remember to install your new calipers with the bleeder screws in the upper or top position. If after installing you see that they are in a lower position, then you have accidentally switched the left and right calipers. Then you must remove them and reinstall them correctly. Remember, Bleeder Screws UP!

• Buy a service manual for your vehicle. Also, buy a pair of fender covers to keep your greasy paws and brake fluid off your vehicles paint, and also buy a good pair of washable mechanic's gloves. They're worth it!

• When buying a set of wrenches or sockets try to get both SAE and Metric sizes together. Yes, sometimes you will need those Metric sizes. Alas, we live in a global economy, poor wretches that we are. There's a song in there somewhere.

• When compressing the caliper, if you see that brake fluid will overflow, you can remove the excess with a clean turkey baster. Do not re-use the fluid once removed. If you need to add any, use new fluid. It's cheap, so don't try to save a few pennies on your brakes. You may need them.

Warnings

• Brake dust contains asbestos. Take care not to ingest any of it through breathing, eating/drinking, smoking cigarettes, wiping sweat from your brow. Wash thoroughly after you're done.

• Cars are not scary, but they are big and heavy. Take extra care to block the wheels, set the emergency brake, test the jackstands with those couple of shoves, and put the wheels under the car while they're off.

• Know where your extremities are. In the close quarters under the wheelwell, trying to loosen stubborn bolts, you can easily bang up your knuckles. Being aware of this will keep those minor bangs from becoming major ones.

Things You'll Need • Replacement parts • Jack stands • Jack (preferably a floor jack) • Rags • Removal tools, usually three or four wrenches and a lug wrench • A clean, well-lighted place big enough to park a car in • Large flat screwdriver • Rubber mallet • A set of SAE/Metric wrenches and sockets • Hammer, breaker bar, Liquid Wrench, torch (removing stubborn bolts) • Wire brush • Anti-squeal paste • Brake lubricant • Carb cleaner • A friend (for bleeding brakes only) • Mechanics' hand cleaner • Jar or can with appropriate size hose for bleeding brakes • Brake fluid [DOT 3] or better

How to Remove an Inside Door Panel from a Car Sometimes the car window will not roll up or down. Sometimes the car door handle will not open the door. Then you know it is time to take the inside door panel off.

Steps 1. Open the car door. 2. If the lock sticks out of the top of the inner panel, remove it--usually by

unscrewing it.

3. Locate the inside door lever that opens the door. Pull on it so that you can see if there is a screw underneath the lever. Remove the screw and remove the hard plastic casing around the door lever.

4. Look underneath the armrest. You will find screws that hold the armrest to the door. (Sometimes these screws are under plastic covers that have to be popped out with a flat screwdriver.) Remove the screws. Remove the armrest. If your windows are electric, remove the wires attached to the armrest by squeezing the plastic sides of the plug-ins.

5. Remove the window crank (if your windows are not electric). Sometimes there is a screw in the center of the crank underneath a decorative cover (old VW Beatle). Pry off the cover and unscrew. Sometimes there is a circlip around the base of the crank. Pry the circlip away from the window crank with a flat screwdriver.

6. Use a wide flat putty knife to pry the bottom of the panel away from the metal part of the door. The panel is held to the metal part of the door by means of several plastic grommets, attached to the back of the cardboard panel, that fit into holes. Gently pop the grommets out of their holes, trying not to rip them out of the cardboard panel.

7. When all of the grommets have been removed check to see if there are any screws up near the rear-view mirror or on each side of the window sill (Audi). Remove screws if there are any.

8. Lift the sill up out of its slot by the window and pull the panel away from the door.

9. Carefully pull the plastic away from the door so you can see what needs repair.

Tips • Each car manufacturer is slightly different so you may have to figure some things

out for yourself. Perhaps an internet search will show pictures. • Some cars use a Phillips screwdriver, others use Allen wrenches, some use a 12

point screwdriver. • Window parts are often available on eBay.

Warnings • When ordering parts be sure you only order the parts for the exact door you are

working on: The driver's side is considered the left side of the car. The passenger side is the right side.

How to Remove Stick on Lettering from a Vehicle It's actually pretty easy.

Steps 1. Get a pocket knife, some acetone (nail polish remover) and a rag. 2. Under a corner, pop the letters or numbers or logo off the vehicle. 3. Scrape the extra adhesive off, and use the acetone to finish it all off. 4. Buff with rag and enjoy it.

Tips • Don't gouge the paint off, and work outside (acetone stinks).

Warnings • Make sure that the acetone wont ruin your finish, test somewhere hidden (inside

of a door or by the bumper usually works).

How to Quiet a Noisy Fan Belt The first step is to identify which belt is making all the noise. If your vehicle squeals right after you start it but before you even touch the steering wheel then it is most likely your alternator belt. If the noise happens when you turn the steering wheel then look to the power-steering belt. If your vehicle has only one wide belt (called a serpentine belt) that is the one to work on.

Steps 1. With the motor OFF press down on the top of the belt. There should be only

enough slack so the belt depresses less than an inch -if there is more the belt needs tightened and/or replaced, but meantime it can be silenced like this.

2. Again, with the motor OFF rub barsoap on the sides and inner surface the full length of the belt. If you have a serpentine belt just rubbing the soap on the inner surface will be enough.

3. Start the motor. If the noise is still there rub more soap on the belt. This lubricates the belt and the pulley so that they don't squeal when they aren't turning at the same speed.

Tips • If the noise is continuous and/or there is smoke coming from one of the pulleys

then you must see a mechanic RIGHT AWAY as that component has a BIG problem and needs professional help.

• If you have just had your serpentine belt replaced and it is squeaking, it may just need to be tightened. All new belts will stretch in the first couple of days and usually need to be brought back to mechanic for a follow-up tightening.

• A quick check to see if it is the belt and not a bearing, is to drip a couple of drops of brake fluid son it while the engine is running. The belt will be quiet immediately. Do not use any oil based product.

Warnings • Remember this is only a temporary fix and will not take the place of correctly

tensioned belts and functioning engine components.

How to Pick a Tool for Out of View Use What do you do when there is a hard to see screw and you don't know what kind of screwdiver or size socket you need? Say you are working on a large appliance and you don't know if you have all the tools you need -- but aren't ready to move it away from the wall, or you would have to take some of it apart to see what comes next -- but you aren't ready to actually start the project. What if you need a part -- but you can't see the part number... It is surprising how often this simple trick can be used.

Steps 1. Press a finger (the spot with your finger print), or piece of clay into the head of

the screw (or whatever is there) really hard (if using finger, gently for clay) and "read" the impression is left on your finger or clay.

Tips • This works for things like raised symbols, numbers, or writing on plastic or metal:

a company name, + or - , a part number, etc. --- but it will be backwards! • It may not work if you have calluses... find some softer skin to press with.

Warnings • Always be careful when putting a finger or a hand into a place you can't see. You

could get a burn or a cut, or your hand or finger(s) could get stuck if forced into a small space.

Things You'll Need

• finger or clay

auto repair

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