Your preseason preparation...
Your preseason preparation might not include testing at places like Daytona, but you do need to prepare nonetheless. Draw on data you had recorded from last season to plan out how you'll set up your car for the new season. Here are some tips.
We approach the new season hopefully and with newfound knowledge. We now have another year under our seatbelts and, with that, a better understanding of our asphalt race cars. We can't let that go to waste as we prepare for our '08 season.
I believe in priorities because you can make gains faster when you take care of the high priorities first. Smaller gains can come later on after the more important aspects of setup are resolved. And, some aspects of chassis setup build on other aspects. So, here, in order of logic and importance, are a list of setup parameters we need to address to make our cars fast and consistent.
The first step in the process of preparing for the new season is to consider all performance-related items and how they worked last season. Plan out changes that can help improve performance or durability. Both of these are necessary components that will be needed to win championships. Here are what we consider to be the 10 most important areas of chassis setup, with number one being the most important.
1. Front-End Geometry We always start with the front-end geometry on a stock car. In most cases, getting a car to turn involves being able to work effectively with all of the other setup parameters. If this component on your car isn't right, then the whole car will suffer, no matter what else you do.
Pushing is the number-one complaint from drivers. The main reason a car will be tight and not want to turn is because the front end isn't designed correctly. The moment center must be located correctly for your type of racing and the cambers must be set, again toward your setup style and track conditions.
The dynamics of the moment center and the effects of camber change have been explained before. We've continually pressed these issues because of the extreme importance they have. Long gone are the days of saying that the MC is not important.
If the Moment Center is moved...
If the Moment Center is moved to the right, the front suspension of the car tends to get stiffer, much like increasing the spring rates. Notice how the moment arm gets shorter as the MC moves right. A location that is more to the left makes the front end softer and helps the car turn better.
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, the front end would get stiffer. Sliding the MC left makes the suspension softer. The effect is huge. It's this sliding scale situation that determines the stiffness of your front end.
Cars that don't turn well are likely to have poor MC designs. I can't tell you how many times I've refined the MC location in a car and had it totally change the way the car turned, for the better. I've 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 not advantageous to have the rear end 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 needed. But the most useful rear steer will occur only on acceleration and not at mid-turn.
We want minimal rear steer...
We want minimal rear steer as the car negotiates the turns. A small amount of steer to the left will help tighten the car. If overdone, the car will push. For three-link cars, set the control arm angle so that the front mount is 1/3 of the total travel distance higher than the rear mount.
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 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 (over 0.030 bump in an inch of travel is considered negative by most designers), excessive Ackermann (over 1/4 degree added steer in either wheel in 10 degrees of steering input is considered excessive), and incorrect steering quickness.