Before we get into the specifics of what makes up the best design for a particular track, it is important to understand some basic information about why the cambers change in your race car. Here are the five most important effects that cause camber change:
1. Magnitude of chassis roll
2. Magnitude of chassis dive
3. Control arm lengths
4. Control arm angles
5. Spindle height
Roll Angle As the car enters the turns, two things happen to affect camber change. First, there's the action of the front wheels. The right front wheel is always in bump (moves up in relation to the chassis), and the left front wheel either stays close to the same position (as is the case with most late models on moderately-banked racetracks), in rebound (moving down in relation to the chassis normally associated with dirt cars using very soft right rear springs), or in compression (when the track is very high-banked with lots of grip).
(above & right) We can learn to look at a tire and see the approximate degree of camber.The tire on the left is at around 31/2 degrees of camber while the tireon the right is at 6 degrees of camber.
Another thing happening, that is often ignored, is that the chassis itself is rolling. As the chassis rolls, the upper chassis mounts are moving to the right (in a left hand turn). If the chassis mounting points are moving, so are the control arms as well as the upper ball joints. If the upper ball joints move laterally in relation to the lower ball joints, we have a change of camber caused by chassis roll.
Dive As the car dives, the upper ball joints are drawn in towards the center of the car. The lower ball joints are either drawn in or pushed out, depending on location of the chassis mounts (lower or higher than the lower ball joints). Because the lower control arms are longer and have less degree of angle than the uppers, the amount of camber change effect is much less. The upper arms have the greatest influence because of their amount of angle from horizontal.
Both of the front wheels will gain negative camber (top moving inwards toward the center of the car) as the car dives. At high-banked, high-downforce tracks, there is much more dive than roll. Close attention should be paid to the amount of camber change due to chassis dive.
Now, we can understand that if we try to determine the amount of camber change by bumping the wheel with the car at static ride height, we will not see a true picture of our camber change characteristics. The true camber change, relative to the racing surface, results from a combination of roll effect and dive effect measured together in combination.
Upper Arm Lengths The lengths of the upper control arms will influence the amount of camber change that occurs in each front wheel. The correct arm lengths for your car will depend on the overall design of the front end relative to the racetrack where you intend to compete.
The best way to know how the length of the arms will affect the camber change in your car is to use a geometry software program. This will allow you to install different-length arms without changing the arm angle. You can see the camber change effects that different lengths have in order to decide which length arms are best for your car.
Shorter arms affect more camber change from chassis dive. Longer arms affect more camber change from chassis roll. There is an optimum length control arm associated with camber change for each side of the car.