2013 natef task area a-5 brake systems 7-2013 a. general brake system diagnosis b. hydraulic system...

2013 NATEF Task Area A-5 Brake Systems7-2013

• A. General Brake System Diagnosis

• B. Hydraulic System Diagnosis & Repair

• C. Drum Brake Diagnosis & Repair

• D. Disc Brake Diagnosis & Repair

• E. Power Assist Diagnosis & Repair

• F. Wheel Bearing, Parking Brake, Electrical D & R

• G. Anti-lock Brake & Traction Control Systems

NATEF Task Area A-5 Brake SystemsA. General Brake System Diagnosis

Identify and interpret brake system concerns; determine necessary action.A5.A.1

Research applicable vehicle and service information, such as brake system operation, vehicle service history, service precautions, and technical service bulletins.

A5.A.2

Describe procedure for performing a road test to check brake system operation; including an anti-lock brake system (ABS). Consider doing it in a parking lot!

A5.A.3

A brake inspection should consist of:1. A road test to check brake operation2. A wheels-off inspection to measure brake rotor thickness. Every brake rotor has a spec for thickness to ensure safe operation. When they are outside this measurement, they cannot be used.3. Measuring the thickness of the brake material to determine if it is above a minimum thickness. The brake pads not only provide the necessary friction, but also help dissipate heat. If pads are too thin, they cannot perform these two important functions.4. Inspecting the brake calipers for damage such as torn dust boots, sticking pistons, etc. If the brake calipers are not performing as designed, they will not allow enough force to be applied to the brake pads to stop the vehicle.

The feel and sound of ABS.When ABS is activated, you may experience a slight vibration or a rapid pulsation of the brake pedal almost as if the brakes are pushing back at you. At times, you will feel the pedal suddenly drop. The valves in the ABS unit may make a grinding, scraping or buzzing noise. This means your ABS is working. Continue to apply firm pressure and steer. Do not take your foot off the brake pedal.

Install wheel and torque lug nuts.A5.A.4

Complete work order to include customer information, vehicle identifying information, verify customer concern, related service history, cause, correction.

Have the Customer Sign & Date the R.O.

“Oldie”

Locate and interpret vehicle and major component identification numbers (VIN, vehicle certification labels, calibration decals).

“Oldie”

NATEF Task Area A-5 Brake SystemsB. Hydraulic System Diagnosis & Repair

Diagnose pressure concerns in the brake system using hydraulic principles (Pascal’s Law).

A5.B.1

Measure brake pedal height, travel, and free play (as applicable); determine necessary action.

A5.B.2

Check master cylinder for internal/external leaks and proper operation; determine necessary action.

A5.B.3

Remove, bench bleed, and reinstall master cylinder.A5.B.4

Diagnose poor stopping, pulling or dragging concerns caused by malfunctions in the hydraulic system; determine necessary action.

A5.B.5

Inspect brake lines, flexible hoses, and fittings for leaks, dents, kinks, rust, cracks, bulging, and wear; check for loose fittings & supports; determine necessary action.

A5.B.6

Replace brake lines, hoses, fittings, and supports.A5.B.7

Fabricate brake lines using proper material and flaring procedures (double flare and ISO types).

A5.B.8

Select, handle, store, and fill brake fluids to proper level.A5.B.9

Inspect, test, and/or replace components of brake warning light system.A5.B.10

Identify components of brake warning light system.A5.B.11

Inspect, test, replace metering (hold-off), proportioning (balance), pressure differential, & combination valves.

“Oldie”

Inspect, test, replace, and adjust height (load) sensing proportioning valve.“Oldie”

Bleed and/or flush brake system.A5.B.12

NATEF Task Area A-5 Brake Systems1. B. Hydraulic System Diagnosis & Repair

Flush hydraulic system.“Oldie”

Test brake fluid for contamination.A5.B.13

Green: Battery OK, i.e.: No water contained in the brake fluid. Yellow: Less than 1% of water content in brake fluid. Yellow/ Yellow: Approx. 2% of water content in brake fluid. Yellow/ Yellow/ Red: Approx. 3% water content in brake fluid. The brake fluid should be changed. Yellow/ Yellow/ Red/ Red: At least 4% of water content in brake fluid. The brake fluid must be changed urgently.

NATEF Task Area A-5 Brake SystemsC. Drum Brake Diagnosis & Repair

Diagnose poor stopping, noise, vibration, pulling, grabbing, dragging or pedal pulsation concerns; determine necessary action.

A5.C.1

Remove, clean, inspect, and measure brake drum diameter; determine necessary action.

A5.C.2

Refinish brake drum & measure final drum diameter; compare with specifications.A5.C.3

Remove, clean, and inspect brake shoes, springs, pins, clips, levers, adjusters/self-adjusters, other related brake hardware, and backing support plates; lubricate and reassemble.

A5.C.4

Inspect wheel cylinders for leaks & proper operation; remove & replace as needed.A5.C.5

Pre-adjust brake shoes and parking brake; install brake drums or drum/hub assemblies and wheel bearings; perform final checks and adjustments.

A5.C.6

NATEF Task Area A-5 Brake SystemsD. Disc Brake Diagnosis & Repair

Diagnose poor stopping, noise, vibration, pulling, grabbing, dragging, or pulsation concerns; determine necessary action.

A5.D.1

Remove and clean caliper assembly; inspect for leaks and damage/wear to caliper housing; determine necessary action.

A5.D.2

Clean and inspect caliper mounting and slides/pins for proper operation, wear, and damage; determine necessary action.

A5.D.3

Remove, inspect, and replace pads and retaining hardware; determine necessary action.

A5.D.4

Disassemble and clean caliper assembly; inspect parts for wear, rust, scoring, and damage; replace seal, boot, and damaged or worn parts.

“Oldie”

Lubricate and reinstall caliper, pads, and related hardware; seat pads and inspect for leaks.

A5.D.5

Clean and inspect rotor; measure rotor thickness, thickness variation, and lateral runout; determine necessary action.

A5.D.6

Remove and reinstall rotor.A5.D.7

Refinish rotor on vehicle; measure final rotor thickness and compare with specifications.

A5.D.8

Refinish rotor off vehicle; measure final rotor thickness and compare with specifications.

A5.D.9

Retract and re-adjust caliper piston on an integrated parking brake system.A5.D.10

Check brake pad wear indicator; determine necessary action.A5.D.11

Describe importance of operating vehicle to burnish/break-in replacement brake pads according to manufacturer’s recommendations.

A5.D.12

30/30/30 Burnish Procedure

• Perform 30 stops from 30 miles per hour with a 30-second cooling interval between stops. These stops will be performed at a decelerating rate of 12 feet per second or less. This means that it should be a gentle easy stop.

• The 30/30/30 Burnish Procedure beds the pads and shoes into the rotor and drums. It also deposits the necessary friction transfer to the rotors and drums for optimum brake performance.

• Following this procedure also assures that your customer will have excellent brake performance from the first time he or she drives the car after brake service has been performed. You should not depend on your customer to break in the brake job. The only way to assure that it is done correctly is to incorporate it into your brake job test drive.

NATEF Task Area A-5 Brake SystemsE. Power Assist Units Diagnosis & Repair

Check brake pedal travel with, and without, engine running to verify proper power booster operation.

A5.E.1

Check vacuum supply (manifold or auxiliary pump) to vacuum-type power booster.

A5.E.2

Inspect vacuum-type power booster unit for leaks; inspect the check-valve for proper operation; determine necessary action.

A5.E.3

Inspect and test hydraulically-assisted power brake system for leaks and proper operation; determine necessary action.

A5.E.4

Measure and adjust master cylinder pushrod length.A5.E.5

NATEF Task Area A-5 Brake SystemsF. Wheel Bearing, Parking Brake, Electrical Diagnosis & Repair

Diagnose wheel bearing noises, wheel shimmy, and vibration concerns; determine necessary action.

A5.F.1

Remove, clean, inspect, repack, and install wheel bearings; replace seals; install hub and adjust bearings.

A5.F.2

Check parking brake cables and components for wear, binding, and corrosion; clean, lubricate, adjust or replace as needed.

A5.F.3

Check parking brake operation and parking brake indicator light system operation; determine necessary action.

A5.F.4

Check operation of brake stop light system.A5.F.5

Replace wheel bearing and race.A5.F.6

Remove and reinstall sealed wheel bearing assembly.A5.F.7

Inspect and replace wheel studsA5.F.8

NATEF Task Area A-5 Brake SystemsG. Anti-lock Brake & Traction Control Systems

Identify and inspect electronic brake control system components; determine necessary action.

A5.G.1

Identify traction control/vehicle stability control system components.A5.G.2

Describe the operation of a regenerative braking system.A5.G.3

Diagnose poor stopping, wheel lock-up, abnormal pedal feel, unwanted application, and noise concerns associated with the electronic brake control system ; determine necessary action.

A5.G.4

Diagnose electronic brake control system electronic control(s) and components by retrieving diagnostic trouble codes, and/or using recommended test equipment; determine necessary action.

A5.G.5

Depressurize high-pressure components of an electronic brake control system.A5.G.6

Bleed the electronic brake control system hydraulic circuits.A5.G.7

Remove and install anti-lock brake system (ABS) electrical/electronic and hydraulic components.

“Oldie”

Test, diagnose, and service electronic brake control system speed sensors (digital and analog), toothed ring (tone wheel), and circuits using a graphing multi-meter (GMM)/digital storage oscilloscope (DSO) (includes output signal, resistance, shorts to voltage/ground, and frequency data).

A5.G.8

Diagnose electronic brake control system braking concerns caused by vehicle modifications (tire size, curb height, final drive ratio, etc.).

A5.G.9

Interaction Between the ABS System & a Compact Spare

Because ABS brakes monitor wheel rpm, any difference in wheel rpm “confuses” the ABS

system, causing it to activate even on dry roads. Because a compact (“donut”) spare rotates faster than a normal tire, this difference “kicks-in” the ABS system when you don’t expect it. Some car

models disable the ABS by a connector attached to the spare. Be sure to reconnect this when

replacing your spare.

Note that if you change tire size (such as smaller front tires), you may affect your car’s computers,

such as ABS, fuel, traction control, etc. Check with your tire dealer to learn how tire size differences

may impact your car.

ABS Light + Check Tire Pressure Light Problems

2013 natef task area a-5 brake systems 7-2013 a. general brake system diagnosis b. hydraulic system...

brake systems

brake operation

brake pads

parking brake

brake calipers

brake inspection

brake material

brake system operation

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