the shock settings

8/12/2019 The Shock Settings

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The shock settings that come with the Long Travel Kit are built around dune riding. The majority

of the cars that end up with ATV's LT kit end up racing around in the dunes where the surface is

for the most part smooth and slightly soft. A stiff spring and lighter damping rates are perfect forthis setting. !T" if you want to play on a track" be it a motocross track" out door off road track

or a stadium track" you need to do some changes.

The spring rates that came with my LT kit were as follows# $ront shocks % single & pound

spring. (ear shocks % )ual rate setup with a &*+ pound tender and a &+, pound main. These aretoo stiff for the off road stuff. - switched to a dual rate up front and used a &+ pound tender and

a */, pound main. 0n the rear - went down to a &,, pound tender and a &*+ pound main.

)rastically softer than what the car came with.

y going to the softer spring settings my damping was a lot closer" but it was still too soft on

both compression and rebound. - ended up completely changing the shim stacks and jets a couple

of times. 1ere's a mapping of the stacks and jets that - finally decided on and used for the 2ace

3eries. 4- unfortunately don't have the originally supplied shim data to compare against5

Recommended Shim Stacks and Shaft Jetting

for ATV Racing's Long Travel Custom Axis

Shocks

Front Compression Front Reound Rear Compression Rear Reound

.,, 6 .,, .,&, 6 .,, .,&, 6 .7+, .,&+ 6 .,,

.,,7 6 .7,, .,&, 6 .,, .,&, 6 &.&,, .,&+ 6 .7+,

.,,7 6 &.,,, .,, 6 .7,, .,, 6 &.*+, .,&+ 6 &.&,,

.,,7 6 &.&,, .,, 6 &.,,, .,, 6 &.8+, .,&* 6 &.*+,

.,,7 6 &.*+, .,, 6 &.&,, .,, 6 &.+,, .,,/ 6 &.88+,

Front Jet , Rear Jet /

-f - were to run the 2ilot on one of the large out door tracks" such as 9randon" - would probably

go up on spring rate for both front and rear and leave the shock damping where it is" or goslightly stiffer on the compression damping. The reason for the spring changes are that the

speeds are so much higher and the jumps are not near as radical compared to a stadium track.

:ow that -'ve covered the basics on shocks and spring setup for a Long Travel 2ilot" how about

actually looking at chassis tuning;

3o far" all -'ve done is cover the suspension and how it works.


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3ome key terms#

Ackerman Angle% The angle of the two steering arms which produce toe out on turns.

Alignment% The process of adjusting the position of the tires and steering a6is to bring them to aspecified" predetermined position.

!ump Steer% The amount of toe in or out that is induced as the suspension goes through it's

travel.Camer% The angle of the king pins from vertical as looking parallel to the chassis' longitudinal

a6is.


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with two sets of measurements % the cross and side measurements won't be the same as each

other5.

:ow put the car back on it's wheels and block up the rear end. 2ull off the shocks" pull thesuspension to &@* travel and set the rear wheels so that they have no camber 4wheels sit

vertically5 and you want &@? of toe out. This lets the suspension come to , toe 4due to fle65when the drive train is under load. The 9aster should be set so that at full e6tension" the upper

ball joint on the rear carriers just barely touches the springs. As the suspension compresses" theball joint will rotate away from the spring.

Fou'll notice that as you change the settings" CVC(FT1-:E from the side to side measurements

to the cross measurements will change on you. -t's VC(F frustrating and takes Duite a bit of timeto get done correctly. 4eer makes the time needed L0:EC( % and you have to go back and

recheck it all later.5

The front end is pretty easy. $ind 4beg@borrow@steal5 a set of turn plates and a caster camber

gauge and follow the instructions. )o the caster first" then camber % go back and check caster asyou adjust for camber and then finally do toe out % &@B?.

Toe 0!T on the front end will help the car dive -:T0 the corner. Toe -: on the front will help

the car come 0!T of the corner. 0n the rear end" it's e6actly the opposite.

A &issertation on Front nds ( Sort of))))

Long* Complicated and $roal+ $rett+ !oring to ,ost

$eople-

Let's start with the definitions# 4you probably saw them at the top of this5

Ackerman Angle% The angle of the two steering arms which produce toe out on turns. This also

can be considered the relationship of the angle between the two wheels as they go through the

steering motion.

Alignment% The process of adjusting the position of the tires and steering a6is to bring them to a

specified" predetermined position.

!ump Steer% The amount of toe in or out that is induced as the suspension goes through it's

travel.

Camer% The angle of the king pins from vertical as looking parallel to the chassis' longitudinal

a6is.


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Contact $atch% the part of the tire that actually touches the ground.

Scru Radius% The distance between the center of the tire and the steering a6is when measured

at the road surface.

Toe% An angle of a tire" relative to straight ahead" if viewed from above.

Toe Angle% The actual amount that the tire differs from pointing straight ahead.

Toe %n% A condition where both tires of an a6le are positioned so they are closer together at thefront than the rear.

Toe "ut% A condition where both tires of an a6le are positioned so they are closer together at

the rear than the front.

Track% The lateral distance between the centers of tire contact of a pair of wheels.

Track Change% The change in wheel track resulting from vertical suspension displacements of

both wheels in the same direction.

3o" what's all this crap mean;


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my thinking is that you'd have less horiHontal travel as the arm moves through it's travel % more

on that later % maybe... 3o" if we shortened the arm 4and adjusted the mounting point to keep the

toe that we started with5 then the ackerman angle would be greater 4the desired result that wasspoken of in the previous posts5. -'m either correct or completely backwards=

3o" back to our suspension design.

The entire idea of a suspension design is to keep the contact patch as large as possible in all

aspects of the suspension@wheel movement. 9ertain factors will make a huge difference in this.

King 2in Angle and 9aster are probably the two biggest factors.

$irstG King 2in Angle % This is the line drawn through the spindle's pivot points 4draw a line from

the pivot point of the top ball joint thru the bottom ball joint and then project it on to the ground5.

This angle and the distance from the center of the tire is what determines scrub radius. This is the

amount of pivoting the contact patch does around the king pin angle % if the line we drew ends up

pointing directly to the middle of the contact patch" 4assuming that we have no camber or casteryet % everything's set perfectly vertical so far5 then we'd have no scrub radius. 4-'m gonna call this

the king pin's contact point % kpcp for now5 The wheel would pivot right around the middle ofthe contact patch. This is a pretty desirable thing % so far....

!T" you want to induce a bit of scrub % you want the contact patch to move around the king pin

angle % it forces the tire to bite by inducing scrub. A bit is a good thing.

:ow" let's toss in caster % by leaning the king pin back you make the contact patch move behindthe kpcp. This gives the car steering stability and controls the bite of the contact patch. Think

about trying to push a grocery cart % those casters follow the kpcp. -t makes you the boss and not

the wheels when you try to steer. >ove the kpcp behind the contact patch and you have a wheelthat's trying to be driven from behind % would be like trying to keep that caster on the grocery carfrom spinning around when you start pulling on it after you've been pushing it. Too much

forward caster 4- think it's called positive % never can remember which is which5 and you start

getting a contact patch that's overbearing and takes control % makes the car over steer and a bitchto steer.

>ove the top of the king pin backward too far and then you end up swinging the contact patch

around the kpcp % and you start inducing scrub and the car will develop a push. !sually the

optimum setting is somewhere around 8 degrees of negative caster.

:ow let's toss in 9amber.

The main idea of camber is to keep the contact patch as large as possible in corners. % back to our

perfect suspension. As the car chassis goes into a left hand turn" the chassis would roll about it's

longitudinal a6is to the right % now our tires are leaning to the right and we're turning left %contact patch would move towards the inside of the right tire and the outside of the left tire %

problem is" since we're turning left" we want the outer 4right5 tire's contact patch to move towards

the -:3-)C of the tire because the tire's profile will roll and we're trying to load the tread with as


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even of a load as possible. Cver watch a 9A(T car on an oval; They have the right side tire

leaning in and the left side tire leaning out % so when the car is at full lateral load" the tires are

actually sitting flat against the surface. $ull contact patch has been achieved.

!.T /A%T 0there's more-1C(=== Fou

can use this to design a system that makes the camber change as the suspension goes thru it'smotion % and since the suspension on the outside of the car 4during a turn5 compresses % and thechassis rolls to the outside % we make the contact patch stay nice and big and under the tire

instead of moving out towards the outside of the tire. 2retty cool" eh;


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the shock settings

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