GMC 4000 Series Service Manual page 117

Sec. 3A
Page 110
FRONT END ALIGNMENT
C A M B E R A N D K IN G P IN IN C L IN A T IO N
B MINUS A
C
D
E MINUS F
G
K MINUS L
FRONT END INSPECTION
Before checking front end alignment, the fol­
lowing front end inspection should always be made:
1. Check tires for proper inflation.
Rim-to-floor dimension should be the same at each
wheel.
2. Check wheel installation and run-out.
3. Check wheel bearing adjustment.
4. Check steering tie rod and drag link ends
for looseness.
5. Check king pins for looseness.
CHECKING A N D CORRECTING
FRONT WHEEL TOE-IN
Incorrect toe-in results in excessive tire wear
caused by side slippage and also unstable steering
with a tendency to wander. Toe-in may be measured
from center of tire treads or from inside of tires.
Measurements at both front and rear of axle (see
"E" and "F," fig. 1).
When setting "toe-in" adjustment, the front
G M C S E R V I C E M A N U A L
T O E -IN
...................................................
................................................
........................................... King Pin Inclination (Degrees)
......................................................
...................................................
................................King Pin Inclination (Inches)
Refer to "Specifications" for correct dimensions.
Figure 1 — Front End Alignm ent Chart
NOTE:
Vertical
FR O N T A X L E CASTER
K IN G PIN IN C L IN A T IO N
Camber (Inches)
Camber (Degrees Positive)
Toe-in (Inches)
Caster (Degrees Positive)
suspension must be neutralized; that is, all com­
ponent parts must be in the same relative position
when making the adjustment as they will be when
in operation. To neutralize the suspension, the ve­
hicle must be rolled forward 12 to 15 feet. By roll­
ing the vehicle forward, all tolerances in the front
suspension are taken up and the suspension is then
in normal operating position. Neutralizing the front
suspension is extremely important, especially if
the vehicle has been jacked up in order to scribe
the tires, otherwise the front wheels will not re­
turn to the normal operating position due to the
tires gripping the floor surface when the vehicle
is lowered on the jack.
IMPORTANT
"TOE-IN" MEASUREMENTS MUST BE MADE
AT THE HORIZONTAL AXIS OF THE WHEEL.
"Toe-in" is corrected by loosening clamp bolt
at tie rod ends, then turning tie rod with pipe
wrench until wheels have proper toe-in. On some
vehicles with power steering, loosen the power
G Caster A n gle
K ing Pin $
T-3073