camber of front struts? what does this acheive? (Read 1,659 times)

[mini89]

what does increasing/decreasing the camber/angle of your struts achieve

[Rusty]

From a book i studied while racing ministocks. American oval racing.
Same principals apply.

Circle Track Camber
In circle track racing, we use positive camber on the left-front wheel of the car and negative camber on the right-front wheel. We can easily check the amount of camber by using a caster/camber gauge and reading the amount directly on the camber bubble vial.

We have learned some interesting and important aspects of tire camber for short-track racing. We have always known that a racing tire will flex under the stress of cornering and the tread will move and roll under the wheel when the extreme forces associated with cornering are present. Different brands of tires have different stiffnesses of sidewall construction and therefore roll over more or less.

Tire temperatures tell us more about how much static camber we need than anything else. The overall goal is that we need the tire contact patch to be relatively flat on the racing surface at midturn in order for the tire to be able to provide the maximum amount of traction. This is often referred to as the maximum "footprint."

Tire temperatures can alert us to improperly set static cambers. A front tire that is hotter on the inside edge (side toward the inside of the racetrack) usually has too much positive camber in the case of a left-front wheel, or too much negative camber if it is the right-front wheel.
Camber Change
The cambers will change as the car dives and rolls when it enters and negotiates a turn. True camber change is a product of both chassis dive and chassis roll. Gone are the days when we would jack up the wheel and measure how many degrees the camber changed in each inch of bump. Those numbers really don't tell us anything. They are only part of the answer. Chassis roll has an effect that adds or subtracts from what dive does. So what we really need to know is what the dynamic camber is after the car dives and rolls, just like it does in the turns.

The left front always loses a lot of camber, so we need to allow for that in setting the amount of static camber. Generally, if we end up with between 11/42 and 1 degree of positive camber at the left-front wheel after the car dives and rolls, then that tire will have the dynamic camber that it needs.

The right-front camber change is a little different. We can design our car so that the right-front camber does not change after dive and roll. This is actually exactly what that tire wants for most short-track applications. The reason for this is that as we enter the turn, the right-front tire takes a set fairly quickly. If the camber continues to change after that initial set, then the tire will give up traction and the car will usually push.

The right upper control arm angle mostly controls the right-front camber change, so we try to work with that control arm angle. Once we have the proper camber change (zero), we leave that angle alone as we further design our front end for moment center location.