Alignment is a critical part...
Alignment is a critical part of your setup package. This includes toe, bumpsteer, Ackermann, and tire contact patch relationships. A few moments spent checking and refining alignment will make a significant difference in how your car performs. There are racing companies who have built their whole product line around these aspects.
The dynamics of the moment center and the effects of camber change have been explained before. We have continually pressed these issues because of the extreme importance they have. Long gone are the days of saying that the MC is not important.
The influence of the location of the front MC can be compared to a sliding scale. If you could slide the MC to the right, or outside of the turn for you road racers, the front end will get stiffer. Sliding the MC left and to the inside of the turn makes the suspension softer. The effect is huge. It is this sliding scale situation that determines the stiffness of your front end.
Cars that don't turn well are very likely to have poor MC designs. I can't tell you how many times I have refined the MC location in a car and had it totally change the way the car turned, for the better. I have had a lot of feedback from teams who did the same with the same results.
2. Rear Geometry
The second most important item in the setup arsenal is the rear geometry layout in your car. The components that locate the rear end must be evaluated and set correctly. The control arm angles affect the rear steer and the third-link angle can redistribute load upon acceleration. On a metric four-link car, the four control arms determine the rear moment center height too.
It's important to know the...
It's important to know the rates for your springs and shocks. Always rate the springs in the range of compressed height that they will operate in. Dyno your shocks or have someone else do it. Now would be a good time to rebuild them with new seals, and so on.
It is not advantageous to have the rearend steer to the right at any time on asphalt. A slight amount of rear steer to the left has been shown to help provide more traction at the rear and bite off the corners where it is needed. But the most useful rear steer will only occur on acceleration and not at mid-turn.
On a three-link rear suspension you should have the front of your right-side control arm higher than the rear mount by 1/3 of the total amount it will travel in the turns. With setups that use a very stiff right rear spring, the angle of the right trailing arm will need to be less than when using a conventional softer spring because that corner will move less.
3. Steering Geometry
The steering system in your car must be evaluated and any negative characteristics must be eliminated. Negative aspects might include excessive bumpsteer (more than 0.030 bump in or out in for each inch of travel is considered negative by most designers), excessive Ackermann (more than a 1/4 degree added steer in either front wheel in 10 degrees of steering input is considered excessive), and incorrect steering quickness.
Eliminate most of your bumpsteer and Ackermann and install the correct steering ratio for your track that would suite the driver. Ackermann is easily checked by using a laser system or strings. If all of these issues are evaluated and corrected, then you can move on.
It has been found that the misalignment of your tires/wheels presents serious drawbacks to a finely tuned chassis and setup. Alignment issues are defined as: A. rearend alignment, B. contact patch alignment, C. driveshaft to pinion/transmission alignment, and D. engine alignment.
The rearend needs to be aligned at 90 degrees to the centerline of the chassis and/or to a line through the center of the right-side tire contact patches. The right-side tire contact patches will also need to be inline with the right front tire pointed straight ahead.