suspension set-up 101

[jchurch]

Hi All,
Let me start off by saying, WHAT A SITE! I have been looking for this for some time now.
After a year of attending harescrambles with my nephew, I have been blown away by the lack of information on proper set-up. I have been involved in kart racing for 20+ years and set-up is KING in that realm. I am sure we could improve his handling with some adjustments, but I have absloutly no idea where to start. I can tell you what every change will do on a kart, but I'm not sure all the same "rules of thumb" will apply here. Where (or from whom) could imformation on castor, camber, KPI, toe, ackerman, and etc. be found? I am looking more for the effects of changing these variable rather than actual values.
Thanks in advance.......
JC

[Rip_Tear]

There are tons of people on this site that know a TON! Also if you try searching for specific information on here there are tons of previous post about things.

[xc450r33]

Where do you race? And what would you like to know?

[tater_kamik]

this may be of some help http://www.exriders.com/vbb/showthread.php?s=&threadid=86860

[jchurch]

Thanks for the replies. The thread Tater referred me to makes for some very interesting reading, but I am already intimately familiar with the terms and geometry. The recommended numbers that were listed are certainly a help though.
I am more interested in learning what effect a change in any one of these parameters will have on the quad. For instance, what effect will be exhibited by having more than the recommended -4.5 deg. of camber for a XC set-up? How will the quad react to a set up that is closer to neutral (0 deg.)?
This is the beginning of a LONG list of questions that I have about quad set-up, so I want to thank everyone who is willing to reply!!!
JC

BTW…..We live in SE Ohio and he competes in D-11 races and the closer GNCC races.

[Rip_Tear]

Your questions are loaded (not trying to be rude), there are so many different factors to consider; shocks, tires what type of ATV, a-arm length, etc). Sometimes it's worth just trying things (provided that they don't seem dangerous) and see how he likes it. I ride a lot different then most of my friends, they don't know why I set stuff up the way I do, but I can't figure out why they don't set up like me, lol.

[slamdak8782]

Well more camber is for high speed races with turns like in tt. I have some specs I got from this guy who sells gasgas and makes a arms for motocross here you go.
camber 2 degrees
castor 6.5 to 7
toe 1/8 inch toe in

[jchurch]

Rip Tear,
Thanks for the reply. I certainly did not interpret your response as rude. I appreciate all feedback, whether it supports my theories or not! Communication is vital in the learning process and I definitely have a lot to learn.
I understand there are many variables that contribute to the overall handling package. Although I draw my experience from other venues, I believe the most basic underlying principles remain the same. For example, if the entire suspension is set up using common components, with settings which are within the normally accepted range, I fail to see how the effects of an adjustment, of one variable, can be reversed, completely, by the set-up of the remaining variables. I can see how the effects would be greatly diminished or even rendered non existent by changes in the other variables, but not reversed. Please give me an example of this so I can stay away from that situation.

Slamdak,
Thanks for the response. I can definitely see the correlation between corner speed and camber. It makes perfect sense to increase negative camber as the load increases. If you were to take your -2° and change it to -4°, with everything else remaining the same, what effect would it have or would it be noticeable at all?

With the bump steer that appears to be inherent on ATVs, how do you go about setting the toe? Where in the travel do you make your adjustment? Rider on or off?

Thanks for the input…..JC

[slamdak8782]

something I found short and sweet

Suspension Setup
Camber is the amount of degrees that the tire and wheel is tilted in or out at the top in relation to the bottom of the tire. A tire that is tilted in at the top and out at the bottom is said to have negative camber. The farther it angles out at the bottom the greater the amount of negative camber.

For positive camber the top of the tire is farther out then the bottom. The reason for having camber in your front end is as fallows. An ATV's suspension is forced over in a corner and the suspension flexes. With everything in motion, all this force wants to flex the tire more upright, or reducing the amount of negative camber. As a bike enters a corner, the forces tend to bend everything over, adding positive camber.

Caster is the amount of angle the spindle has in relation to the vertical centerline of the wheel. If the upper ball joint is farther forward than the lower ball joint, it is said to have negative caster. If the upper ball joint is farther back than the lower ball joint it is said to have positive caster. The greater the amount of positive caster, the more stable the ATV will be at speed. The less positive caster it has the easier it will steer and the quicker it will turn. As the spindle is laid back, the tire has to lay over more when the front tires are turned. This adds stability. If there is not much angle, the wheel will turn more, making it quicker and easier to turn.

[slamdak8782]

To set the toe you measure between the front and rearwheel you get them both the same distance from each other. To do this move one tie rod. whatever you add to one side you take from the other because adjusting one side affects the other. Finally you mark a spot on the ground in the direct center line of the quad and measure from this point to the same point on each wheel front and back. you end up at about an 1/8 inch in for each wheel Use chalk or equivalent the important part is establishing a centerline and then measuring from there. Also set the castor and camber first. When I used to do cars with lazer alignment I would do camber castor toe in that order. Usually on cars the castor is close. Depending on a-arm style you might not be castor adjustable. Also castor will not affect your toe measurement that much.

[slamdak8782]

also 400ex spindles or gas gas with a 4 to 1 offset wheel yeilds the perfect combo for zero bump steer.

[bradley300]

Originally posted by jchurch


With the bump steer that appears to be inherent on ATVs, how do you go about setting the toe? Where in the travel do you make your adjustment? Rider on or off?

Thanks for the input…..JC

being as the rider weight changes the ride hieght, you will need all changes to be made while the rider is on. making the adjustments with the susension in a raised position will not do anything, as your settings will be greatly changed once the rider gets on the quad and the suspension sags

i think this will help anser all of your questions
http://www.lsracing.com/installguides.php