Spicer Steer Axles Application Guidelines - Manual (Page 26)

< 20 > back AXAG400 – February 2007
3- Alignment/Adjustment
Wheel Alignment
Correct wheel alignment promotes longer tire wear and ease of handling while minimizing strain on the
steering system and axle components. Use vehicle manufacturer’s instructions to inspect wheel
alignment.
Note: Total vehicle alignment is recommended when aligning the steer axle.
Camber
Camber is the vertical tilt of the wheel as viewed from the front of the vehicle. This is machined in at time
of manufacture and is not adjustable. Most roads are made with a crown which means that the
outside/right hand of the lane is lower than the left side of the lane. This improves the drainage of the
road but adversely affects the vehicles handling. Road crown must be compensated for in alignment
settings because a crowned road causes a vehicle to pull or drift to the lower side of the road. Typically
adjustment of camber is made to have slightly more positive camber on the left to compensate for the
road crown. Proper camber, in combination with correct toe and caster, assures that the tread is as flat
against the road as possible under all driving conditions.
“ Positive” camber is an outward
tilt of the wheel at the top.
“Negative” camber is an inward
tilt of the wheel at the top.
“
Caster Adjustment
Caster is the fore and aft tilt (toward front or rear of vehicle) of the steering kingpin as viewed from the
side of the vehicle. The basic purpose of caster is to maintain directional control, giving more on-center
feel to the steering and return the vehicle to a straight ahead position when exiting a turn. A bicycle is a
good example of caster where the front fork is almost always tilted back, giving the front wheel positive
caster. On a Heavy Truck, caster is adjusted when the steer axle is mounted on the front springs.
Typically a wedge shaped spacer block is used to initially set caster.