How Much Caster Split Normal caster splits for most short track asphalt applications are around 2 to 4 degrees of difference. The LF caster might be 1-2 degrees and the RF caster might be 3-5 degrees. Less steering effort is needed on higher banked tracks, so less caster is needed. Also, the tighter the turn radius, the more caster split is needed. Driver preference plays a big role in getting the caster split right for your application.
Camber Defined Camber is when a wheel is tilted, from a front view, so that the top of the tire is either closer to the centerline of the car or farther from it. Negative camber is when the top of the tire is closer to the center of the car than the bottom of the tire. Positive camber is when the opposite is true, i.e., the top of the tire is farther away from the center of the car than the bottom of the tire.
Circle Track Camber In circle track racing, we use positive camber on the LF wheel of the car and negative camber on the RF 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 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 as we turn left. Different brands of tires have different stiffness of sidewall construction. 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 mid-turn in order for the tire to be able to provide the maximum amount of traction it is capable of giving. 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 LF wheel) or too much negative camber if it is the RF wheel.
Camber Change The cambers will change as the car dives and rolls as 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 are only part of the front end dynamics answer and don't really tell us enough. Chassis roll has an effect that adds or subtracts from what dive does. We really need to know where the dynamic camber ends up after the car dives and rolls, just like it does in the turns.
The LF always loses a lot of its static camber, so we need to allow for that in setting the amount of static camber. Generally, if we end up with between 1/2 to 1 degree of positive camber at the LF wheel after the car dives and rolls, then that tire will have the dynamic (after the forces are applied) camber that it needs for the weight that remains after the weight has transferred in the turns.
Right-Front Camber Change The RF camber change is a little different. We can design our car so the RF camber does not change after dive and roll. This is exactly what that tire wants for most short track applications. As we enter the turn, the RF tire takes a set fairly quickly. If the camber continues to change after that initial set, the tire will give up traction and the car will usually push. The right upper control-arm angle mostly controls the RF 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 roll center location.
Spindle Height Spindle height affects the amount of camber change at each wheel. The taller the spindle, the less camber change that will occur. Trends that have taken place in the past 10 years or so have resulted in excess camber change due to the use of shorter spindles. That trend seems to be reversing as car builders move toward using taller spindles.
Measuring Camber Change We can measure camber change by several different methods. In the shop, we can set the chassis ride heights just as they would be at mid-turn on the racetrack and then directly measure the camber at each wheel. To do this, we will need to know the shock travel at mid-turn, which is very hard to estimate. If we look at the shock travel indicators on the shaft of the shock, it always tells us total shock travel, which includes braking, going over bumps, banking changes such as exiting the race track and driving down onto the apron (this could be quite a lot of LF shock travel at some high-banked racetracks), or something as simple as steering the car back and forth to warm the tires before running hot laps.
The easiest and most accurate way to look at true camber change is to use a computer geometry software program. There are several good ones on the market today. You enter the height and width measurements (and fore and aft when using a three-dimensional geometry program) for each ball joint and the chassis pickup points as well as the static camber amounts. These programs let you enter estimated dive and roll numbers. When you calculate these numbers, the dynamic camber at each wheel is shown. That way, you will know exactly what is happening with your wheel cambers.
Remember that caster settings are mostly adjusted for driver preference and comfort, and camber settings are important so the front end will have the maximum amount of tire footprint and traction to use to turn the car at mid-turn. Many driver-related problems come from camber change problems. Often, a car with a serious push can be helped by analyzing and adjusting the static camber, as well as knowing the camber change. Overlook these two important aspects of front-end geometry and your performance may suffer.