Chassis & Dynamics
Corner Weights
Front/rear, left/right and cross-weight from four scale readings.
Inputsdrag · tap · type
Fig. 18Plan view on the scales
§ How it works
Put a car on four scales and the readings tell you where its centre of gravity sits and how evenly the springs are sharing the load. Three percentages summarise it.
Front and left distribution
where . These two are set by where the mass is. You can only change them by moving or removing weight: relocating the battery, shifting ballast, or the driver going on a diet.
Cross weight
Cross weight (also called wedge) compares one diagonal pair of tires with the other. Unlike the first two it can be changed with ride-height adjusters. Raising one corner's spring perch loads that corner and the one diagonally opposite, and unloads the other two, without moving the centre of gravity at all.
- 50 % means the car is equally stiff turning left and right. This is the target for road courses.
- Above 50 % tightens the car (more understeer) in left turns and loosens it in rights.
- Oval racers deliberately run 52 to 58 % to suit turning one way only.
Doing it properly
Scales must be level with each other to within a millimetre or two. Set tire pressures, disconnect one end of each anti-roll bar, put the driver's weight in the seat, and roll the car to settle the suspension before each reading.