8. Bite Off the Corners

In situations where the exit portion of the track provides less traction and/or the corner is more flat, we might need to develop more rear traction upon acceleration. Just giving the car more rear traction, period, does not help us if the car becomes too tight in the middle of the turns and we could end up with the reverse of what we need.

We must develop ways to create more rear traction on acceleration only. There are ways to do that without changing the handling at other points around the race track. One way is to have a rear spring split, where the right rear (RR) spring has less spring rate than the LR spring. This is very “old-school” and mostly used now days with Street Stock cars.

This develops more cross weight as the car squats on acceleration. Stock cars using the metric–style four-link rear suspension usually need to do this just to achieve a balanced setups with the high rear moment centers in those cars.

Another way to gain bite that we have described in the past involves the use of a spring loaded pull-bar that allows a certain amount of rearend rotation. The idea is to steer the car using different height holes for the rear control arm mounts.

As the rearend rotates on acceleration, the left wheel moves rearward more so than the right wheel creating a slight amount of rear steer to the left. We are only talking about a difference of 0.040- to 0.060-inch, but that is enough to help stabilize our car on exit and provide added bite.

Moving the pull bar or just the third link to the left increases the loading on the LR tire during acceleration. The process of reducing squat loads the third link at each end, an upward loading on the front and a downward loading on the rear. Be careful not to overdue that by moving the link too far left and overloading the left rear tire.

9. The Anti's

Antidive and Antisquat are mechanical influences that can help our transitional phases of entry and exit. Antidive helps prevent sudden nose dive on entry by mechanically resisting the downward motion of the suspension using the rotational forces created through braking.

As the front brakes are applied, the caliper grabs the rotor and the motion of the wheel/rotor tries to rotate the spindle. This force is resisted by the ball joints and control arms. The upper BJ is trying to be forced in a forward direction and the lower BJ is trying to be forced in a rearward direction.

If we arrange our control arm angles, from a side view, for antidive, then as the car dives the upper BJ would move to the rear and the bottom BJ would move to the front. Since the braking forces are in the opposite direction, there is a serious resistant force created which helps prevent the front suspension from moving in compression too quickly while braking.

The amount of resistance is directly related to the degree of side view angle we put in our control arms and the amount of brake force used. The left side suspension usually is designed with about half the angle of the right side in a conventional design.

For the Soft Spring setups, teams often introduce pro-dive into the left front suspension to encourage rapid dive on entry to get the left front down quickly. I don't really encourage that method necessarily, but with the high rebound shocks, this happens naturally so you probably don't need pro-dive.

Antisquat results from the third link trying to straighten out, or become more horizontal as the car accelerates and the rearend desires to rotate. The more third link angle you have, the more antisquat there is. The lateral location of the third link can affect the distribution of load among the two rear tires that results from acceleration and antisquat.

Antisquat is detrimental to corner entry. So, there is a limit to how much you can get away with and still have a decent corner entry. Roughly 8-10 degrees of third link angle is sufficient to promote antisquat and not hurt your corner entry.

10. Aero Package

The very last thing you need to worry about is your aero package. I'm not saying this is not important to some degree, but on short tracks I would stress that aero downforce is over-rated in most cases.

The reason I say that with confidence, is because I have gone up against more aero efficient cars with setups and body configurations that were aero-deficient and still out ran them. Still, teams want the most they can get out of their cars and if all of the above nine items are in order, by all means, go ahead with aero tweaking.

Try to understand how aero downforce is created and then configure your car so that you take advantage of every area where you could produce more downforce. Remember that drag is an important aspect of aero design. Do not seek aero downforce at the expense of aero drag increase.

The newer, soft spring setups that produce low front ends have advantages that are not aero related and that may be more significant than added downforce. A lower CG helps reduce load transfer, leaving more left side loading on those tires. Also, if running on bump fixtures, the front camber change is almost negligent and the car likes less camber change. Those two results of a low and fixed front end ride height account for more gain in performance than the added aero downforce efficiency.

Conclusion

No matter which stiffness you decide to go with, the most important aspect of setup is balance and you achieve that balance with the correct combination of springs, moment centers, sway bars and load distribution.

In past articles presented in Circle Track which you can find online, we detail how to achieve the best results for each area we have spoken about here. Just search the topic and you will usually find more than one article that covers the subject matter more thoroughly.

Once at the track, it may take a few test sessions to help you determine your balance, but if you observe the indicators correctly, then tuning the car for dynamic balance can be done. Then all you have to do is maintain that balance throughout the season and that means resisting making changes that take you outside that envelop. Good luck.