“Using Scrub Radius and Camber Adjustments for Maximum Performance”

The front suspension is designed and adjusted in such a way as to center itself when you let go of the steering wheel. This characteristic of street cars can be applied to the race track by adjusting the front end to more easily turn left. The drawbacks to this idea is that if the car “wants to” turn left all the time, it will “bind” in the straights. If your regular track has tight turns and long straights, a front end setup that binds in the straights will heat the tires and slow you up in the straights. On a track that is more turn than straight, you can probably afford to bind up the car a little in favor of a better turning car. Remember - it's all compromises.

There is a condition known as scrub radius or steering axis offset that will affect the self-centering characteristics of the suspension. If you were to draw a line through the center of the ball joints to the ground, the scrub radius is the distance between that line and the center of the tire contact patch. The larger the distance, the more effort it takes to steer the wheels and the wheel will be more self-centering. Wheel offset and other factors will dictate the scrub radius.

Camber is necessary so that the tire contact patch will be in complete contact with the track surface during cornering. By determining a baseline setting for camber, then checking tire temperatures with your pyrometer, you can slowly adjust camber to bring it to where the tire is performing properly. The standard settings for camber are 2 to 3.5 degree of negative camber for the right front tire, and 0 to 1 degree of positive camber for the left front tire. In the dynamic situation of the right front tire moving into the turn, the compression of the right front suspension due to weight transfer will change the camber of the right front tire to 0 to 1 degree negative camber, and do the same to the left front tire. So in a dynamic situation, both front wheels are near 0 degrees camber and the tire contact patch is flat on the ground.

Mike Loescher is the owner and chief instructor at FinishLine Racing School in Daytona Beach, Florida.  Mike holds Chassis Seminars throughout the year - all around the USA & Canada. View our class schedule or call 386-427-8522 to schedule a private setup date.

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