In brief, roll center is a measure of how easily a car leans when turning. More roll provides more grip which is useful on low traction tracks, but on high-traction tracks you'll typically want less roll to keep the car more stable and easier to drive.
The diagram above shows how the car's roll center is found, but you do not need to actually find the roll center or do any calculations - the important thing is to know whether your car has a relatively high roll center or relatively low roll center.
If you lower the car’s roll center, its chassis will roll side-to-side more easily, and that transfer of weight to the outside wheels creates extra grip on that side, useful on low-grip tracks. If you raise the roll center, the car will resist rolling and be more stable, typically useful on high-grip, smooth tracks.
If you make changes to the roll center, you want to keep the front and rear roll settings similar - having high roll center (HRC) on one end and LRC on the other end will give you a car that handles very strangely.
Front roll center
Lower front roll center
- More chassis roll in turns
- More side grip
- More on-power steering
- Generally suited for low-grip tracks
Higher front roll center
- Less chassis roll in turns
- Less side grip
- Less on-power steering
- Generally suited for high-grip tracks
Rear roll center
Lower rear roll center
- More chassis roll in turns
- More side grip
- More on-power traction
- Less traction under braking
- Reduces traction roll
- Generally suited for low-grip tracks
Higher rear roll center
- Less chassis roll in turns
- Less side grip
- Less on-power steering
- Generally suited for high-grip tracks
Changes to the lower suspension arms typically have a larger impact than changes to the camber link.
Adjusting roll center
The roll center can be changed using many different changes to the suspension, but the most common are:
- Camber link height (inner and outer)
- Suspension arm mount height
- Axle height
- Arm length
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