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Roll Center

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Roll center is something that is commonly tuned in the rear of your racecar using the panhard bar but racers rarely talk about tuning the front end with adjusting the roll center.  This is for a variety of reasons such as, in some classes it just isn't possible, in classes where it is, the other elements affected when changing roll center can include: bump steer, camber, tire contact, caster, shim packer engagement, swaybar preload and more.

Roll center in concept is simple and relates to jacking and anti jacking using instant centers in order to change the leverage effect on the chassis from the center of gravity to the pivoting point of the chassis which it pivots on during cornering.

Simply put, the lower the roll center, the more mechanical leverage is placed on the chassis (at that end, either front or rear), and the more the outside tires are worked.  This is because the mechanical advantage of the weight of the car is more in its fulcrum length and it loads the outside tires more laterally.  Meaning a lower roll center in the front makes the car lean more in the turn and is loading the outside tires more than the inside, and loading them from  top down approach.

If you raise your roll center, then you shorten the fulcrum distance from the ceneter of gravity to the roll center and intern, reduce the amount of roll the chassis has and the amount that the outside tires are vertically loaded.  It means the outside tires aren't pushed into the ground. 

Raising your roll center will make that end of the car loosen up because there is less vertical loading happening on the tires.  They can run cooler as well, but often lack overall grip if the roll center is too high because the tires simply slide across the ground instead of being driven into it.

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