Hummer H1 Service Manual page 409

6-26 Wheels and Tires/Central Tire Inflation System (CTIS)
.
(POSITIVE SENSE)
WHEEL ALIGNMENT CORRECTION
Alignment adjustments should be performed one at a time and
in sequence to avoid errors. Recommended adjustment se-
quence is:
a. caster
b. camber
c. front toe setting
d. rear toe setting
e. steering stops (See Section 8)
Leave the vehicle on the alignment rack for each of the adjust-
ment procedures. This way, angle correction can be monitored
continuously during actual adjustment.
Caster Adjustment
Caster adjustment applies to the front wheels only. It is con-
trolled by turning the pivot bolts and eccentric washers on the
upper control arm brackets (Figure 6-43). A positive caster an-
gle is required on all Hummer vehicles.
Preferred caster angle is +2.5 to +3.5 degrees. Maximum al-
lowable side-to-side variation is 0.5 degree.
1. Support the vehicle weight with the tires on the turntables.
2. Loosen upper control arm pivot bolt locknuts by holding
the bolt head and turning the locknut to allow movement
of the bolts (Figure 6-43).
3. Pry the upper control arm brackets open to allow freedom
of movement of the control arm bushings. The edges of
the control arm bushings are serrated and will be difficult
to move if the brackets are not pried open.
TOE-IN (+)
FRONT
NEGATIVE (-)
CAMBER
Figure 6-42: Wheel Alignment Information
POSITIVE (+)
POSITIVE (+)
CAMBER CASTER
4. Adjust caster angle by turning the eccentrics on the upper
control arm brackets in opposite directions (Figure 6-43).
• Preferred caster is +2.5 to +3.5 degrees and left-right
variation must not exceed 0.5 degree.
• Turning the front eccentric outward and the rear eccen-
tric inward increases positive caster while turning the
front eccentric inward and the rear outward decreases it.
• Shims are available in 0.060 inch and 0.120 inch
(1.5 and 3.0 mm) thicknesses for use behind the control
arm mount brackets if the proper angles cannot be
achieved with the use of the eccentrics alone. This
would be an unusual situation and the vehicle should be
inspected thoroughly for bent or worn parts before in-
stalling shims.
5. Tighten control arm pivot bolt nuts to 260 lb-ft (359 N•m)
torque.
6. Verify correct caster angle at both front wheels. Be sure
side-to-side caster variation does not exceed 0.5 degree.
7. Leave vehicle on rack for camber and toe adjustments.
_______________
TOE-OUT (-)
(NEGATIVE SENSE)
REAR
®