24
ROLL CENTER
1.8
A “roll center” is a theoretical point around which the chassis rolls, and is determined
by the design of the suspension. Front and rear suspensions normally have different roll
centers. The “roll axis” is the imaginary line between the front and rear roll centers. The
amount that a chassis rolls in a corner depends on the position of the roll axis relative
to the car’s center-of-gravity (CG). The closer the roll axis is to the center of gravity, the
less the chassis will roll in a corner. A lower roll center will generally produce more grip
due to the chassis rolling, and the outer wheel “digging in” more. Roll-centers have an
immediate effect on a car’s handling, whereas anti-roll bars, shocks and springs require
the car to roll before they produce an effect.
Roll center is determined by the car’s suspension geometry. Each end of the car has its
own roll center, determined by the suspension geometry at that end of the car.
Depending on the car, front and rear roll center may be adjusted by raising or lowering a
variety of different pivot points of the suspension arms & blocks, such as the following:
• inner upper pin/link
• outer upper pin/link
• inner lower pin
• outer lower pin
For information on adjusting roll center on cars with other adjustment possibilities
(for example, outer lower pins) please refer to the manufacturer’s original detailed
documentation.
FRONT ROLL CENTER
1.8.1
Typically on off-road cars (such as the XRAY XB808) front roll center is adjusted using
the front upper camber link inner mounting position on the front shock tower. Those
same holes on the front shock tower may also be used to adjust camber rise. For more
information, see the section on Camber & Camber Rise.
For information on adjusting front roll center on cars with other adjustment possibilities
(for example, the outer lower pin) please refer to the manufacturer’s original detailed
documentation.
EFFECTS OF FRONT ROLL CENTER ADJUSTMENT
FRONT UPPER CAMBER LINK -
SHOCKTOWER
EFFECT ON FRONT ROLL CENTER
Upper holes (lower roll center)
• Increases steering into corner
• Car is more responsive
Lower holes (higher roll center)
• Decreases steering into corner
• Car is less responsive
• Use in high-grip conditions
ADJUSTING FRONT ROLL CENTER
Front roll center is typically adjusted by
changing where the inner end of the front
upper camber link attaches to the front
shock tower.
IMPORTANT!
Make equal adjustments on both left and right sides of the car. Recheck front camber
after adjusting front roll center.
