If the brake bias is at or nearly out of range for the adjuster in your car, it's time to
The amount of difference you need is directly influenced by the installed motion ratio of the spring and the spring's rate. A soft spring needs more compression rate and less rebound rate, whereas a stiff spring needs a lot of rebound rate and much less compression rate. These are the general rules unless you're trying to "tie down" a corner. Tie-down shocks are becoming less and less desirable.
Shocks affect the motion of the corners of the car and therefore the placement of loads during transitional periods. If one corner of the car is shocked stiff, then as that corner desires to move in compression, more load will be retained by that corner as well as the opposite diagonal corner of the car during the compression cycle only.
If the same stiffly shocked corner is in rebound, less of the overall load will be retained by that corner, and its diagonal corner as well, during the rebound cycle only. That's the essence of shock technology related to handling influences. Plan your shock layout by comparing each of their stiffness to the other corners and to the spring stiffness at the corner you're trying to control.
7. Brake Bias Once the setup has been balanced and the shocks decided on, we need to evaluate the turn-entry characteristics, and brake bias is an important influence at this segment of the track. We don't want to try to solve turn entry problems with the brake bias, we only need to make sure the car stays neutral in handling when the brakes are applied.
Brake-bias influence can be easily determined by entering the corner with medium to heavy braking first and then entering with light braking to see if there's a difference. If there is, try to adjust the brake bias to eliminate the adverse condition.
Once you have made the entry to the corner balanced, check to see if the adjuster is centered. If it is too far to one side, then changes to the brake master cylinder sizes and/or the pad compounds might need to be made in order to maintain a centered bias adjuster. Off-centered adjusters can be very inconsistent.
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 have the 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 it could end up doing 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 racetrack. One way is to have a rear spring split, where the right rear (RR) spring has less spring rate than the LR spring. This develops more crossweight as the car squats on acceleration. Be sure to balance your setup first when changing to a greater spring split.
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 rear end rotation. The idea is to steer the car using different height holes on the rear control arm mounts. As the rear end 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 0.040-0.060-inch, but that's enough to help stabilize our car on exit and provide added bite.
9. The "Anti's" Anti-dive and anti-squat are mechanical influences that can help our transitional phases of entry and exit. Anti-dive helps prevent sudden nose dive on entry by mechanically resisting the downward motion of the suspension by 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. 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.
A trick that was developed a few years ago and is still not well known is to stagger the h