“Using Scrub Radius and Camber Adjustments for
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.