Casterl Camber Adjustment
Caster affects steering stability and steering wheel re-
turnability. Zero (0) caster is present when the upper
ball joint or top strut bearing and lower ball joint are in
the same plane as viewed from the side of the vehicle.
Positive caster exists when the upper ball joint or top
strut bearing is toward the rear of the vehicle in relation-
ship to the lower ball joint. When the upper ball joint or
top strut bearing is toward the front of the vehicle in re-
lationship to the lower ball joint, negative caster is pre-
sent. If the caster at both wheels is not equal, the vehicle
will tend to drift toward the side with the lowest caster.
Camber is the inward or outward tilt of the top of the
wheel. Adjusting camber centers the vehicle's weight on
the tire. Proper camber adjustment minimizes tire wear.
Zero (O) camber is present when the wheel is at a per-
fectly vertical position. The tires have positive camber
when the top of the tire is tilted out, or away from the en-
gine. When the top of the tire is tilted in, there is negative
camber. Incorrect camber will cause excessive stress and
wear on suspension parts. Too much negative camber
will cause wear on the inside tread of the tire, whereas
too much positive camber will cause tire wear on the out-
side tread. If camber is not the same on both wheels, the
vehicle will pull toward the side with the most positive
camber.
To compensate for road crown, most alignment spec-
ifications allow for slightly more negative caster or
slightly more positive camber on the left side of the
vehicle.
Several methods are used to adjust caster and
camber.
Shims Many cars use shims for adjusting caster and
camber (Figure 45-13). The shims can be located be-
tween the control arm pivot shaft and the inside of the
frame. Both caster and camber can be adjusted in one
operation requiring the loosening of the shim bolts just
once. Caster is changed by adding or subtracting shims
from one end of the pivot shaft only. Then, camber is ad-
justed by adding or subtracting an equal amount of
shims from the front and rear bolts. This procedure
allows camber to change without affecting the caster
setting.
Some cars use shims located between the control arm
pivot shaft and the outside of the frame. The adjustment
procedure is the same as just described. Always look at
the shim arrangements to determine the desired direc-
tion of change before loosening the bolts.
Eccentrics and Shims Eccentrics and shims are used on
some vehicles to adjust caster and camber. In some de-
signs, an eccentric bolt and cam on the upper control
arm adjust both caster and camber. To adjust, the nuts on
the upper control arm are loosened first. Then, one ec-
centric bolt at a time is turned to set caster. Both bolts are
turned equally to set camber.
The eccentric bolt and cam assembly (F igtu'e 45-14)
can be located on the inner lower or upper control arm.
Unlike other designs, camber is adjusted first. Some car
models have a camber eccentric between the steering
knuckle and the upper control arm. The camber eccen-
tric is rotated to set camber (Figure 45-15). Caster is set
with an adjustable strut rod.
Slotted Frame The slotted frame adjustment has slotted
holes under the control ann inner shaft that allow the
shaft to be repositioned to the correct caster and cam-
ber settings. Caster and camber adjusting tools help in