Hummer H1 (2002+). Manual - part 103

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Wheels and Tires/Central Tire Inflation System (CTIS) 6-27

05745159

Figure 6-43: Caster /Camber Adjustment

Camber Adjustment

Camber adjustment applies to the front and rear wheels
equally. It is controlled by turning the pivot bolts and eccentric
washers on the upper control arm brackets (Figure 6-43).

Preferred camber for all Hummer vehicles is zero to +0.5 de-
gree at the front and +0.25 to +0.75 degrees at the rear. Maxi-
mum allowable side-to-side variation is 0.5 degree front and
rear.

Support the vehicle weight with the tires on the turntables
and leave the hood closed.

Loosen upper control arm pivot bolt nuts by holding the
bolt head and turning the nut to allow movement of the
bolts (Figure 6-43).

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.

Adjust camber angle by rotating the front eccentric of the
upper control arm bracket (Figure 6-43).

• Rotating the front eccentrics inward decreases camber

(negative direction) while rotating the front eccentrics
outward increases camber (positive direction).

• Rotating the rear eccentrics of each upper control arm

inward or outward in conjunction with the front eccen-
trics will help maintain the previously set caster angle.

Tighten control arm pivot bolts to 260 lb-ft (359 N•m)
torque.

ECCENTRIC

UPPER

CONTROL

ARM

PIVOT

BOLT

PIVOT

BOLT

NUT

BUSHING

FLAT

WASHER

UPPER CONTROL

ARM BRACKET

ECCENTRIC

REFERENCE

HOLE

6-28

Wheels and Tires/Central Tire Inflation System (CTIS)

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Verify correct camber angle at both front wheels. Be sure
side-to-side variation does not exceed 0.5 degree.

Leave vehicle on rack for toe settings and steering stop
adjustment.

Front Wheel Toe Adjustment

Position both front wheels on alignment rack turntables.
Set the front wheels in the straight-ahead position and cen-
ter the steering gear.

Loosen adjusting sleeve clamps on both tie rods
(Figure 6-44).

Turn sleeves until toe measurement is within
specifications.

Tighten the adjusting sleeve clamp nuts and verify correct
toe adjustment.

CAUTION:

Be sure that the bolt and nut on the adjusting

sleeve clamp nut nearest to the geared hub is facing the half-
shaft. The bolt and nut on the adjusting sleeve clamp nearest to
the frame must be facing away (180 degrees) from the stabi-
lizer bar. After adjustment, the lengths of both tie rod end as-
semblies should be the same, plus or minus 1/16 inch (1.6 mm).

CAUTION:

The sleeve clamps must be positioned between

3/16” and 5/16” from the end of the sleeve and the bolt and nut
torqued to 30 lb-ft (41 N•m) (Figure 6-46).

Figure 6-44: Front Wheel Toe Adjustment Points

Verify that steering wheel is centered. Move steering
wheel to the straight-ahead position if necessary.

Rear Wheel Toe Adjustment

Position both rear wheels on alignment rack turntables.

Loosen clamps on both radius rods (Figure 6-45).

Turn the adjusting sleeves until toe measurement is within
specifications.

Tighten clamp nuts and verify toe adjustment.

Figure 6-45: Rear Wheel Toe Adjustment Points

Figure 6-46: Sleeve Clamp Position

SLEEVE

CLAMP

ADJUSTING

SLEEVE

TIE ROD

SLEEVE

CLAMP

ADJUSTING

SLEEVE

CLAMP

RADIUS ROD

UPPER CONTROL ARM

CLAMP

3/16”-5/16”

TORQUE TO

30 LB. FT.

4-1-00

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Wheels and Tires/Central Tire Inflation System (CTIS) 6-29

05745159

STEERING STOP ADJUSTMENT

NOTE: Alignment equipment currently used in the auto-
motive field should be used for steering stop adjustment
procedure. This procedure should be followed if align-
ment equipment is not available.

Removal

Loosen jamnut and remove bolt and jamnut from geared
hub (Figure 6-47).

Remove jamnut from bolt.

Figure 6-47: Steering Stop Adjustment

Installation

Apply thread-locking compound to bolt (Figure 6-48).

Thread jamnut on bolt.

Secure bolt and jamnut to geared hub. Tighten bolt finger
tight.

Adjustment

NOTE: Prior to adjustment, ensure length of each tie rod
is the same. If tie rod lengths are not the same ± 1/8 in. (3
mm), check toe-in alignment setting.

Draw a reference chalk line 30 feet long. Mark this line A
(Figure 6-48).

Position vehicle so that center of left rear and left front
tires are positioned directly on reference line A.

Using a protractor, draw a reference line at 34 degrees
from line A. Mark this line B.

Again, using a protractor, draw a reference line at 36
degrees from line A. Mark this line C.

Figure 6-48: Checking Alignment

Roll vehicle forward until center of left front tire is over
intersection of lines A, B, and C.

Turn steering wheel full left.

If centerline of front and rear of left front tire is over area
between lines B and C, no adjustment is necessary.

If centerline of front and rear of left front tire is not over
area between lines B and C, loosen jamnut and turn bolt all
the way in.

Turn steering wheel until centerline of front and rear of
left front tire is over area between lines B and C.

10. Unscrew bolt until head makes contact with wheel stop on

lower control arm (Figure 6-47).

11. Secure bolt with jamnut.

12. Check for clearance between tie rod clamp and the rim.

13. Repeat adjustment procedure for opposite side.

RIM

TIE ROD

WHEEL

JAMNUT

GEARED HUB

STOP

CLAMP

LINE A

LEFT FRONT TIRE

LEFT

LINE C

LINE B

36°

34°

REAR

TIRE

6-30

Wheels and Tires/Central Tire Inflation System (CTIS)

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CENTRAL TIRE INFLATION SYSTEM

The optional Central Tire Inflation System (CTIS) is unique to
the HUMMER. The CTIS allows the driver to increase or de-
crease tire pressure based on terrain and climate conditions.
The system can also be used to direct air to a tire that has a
leak.

The CTIS controls are located on the instrument panel. An in-
flate/deflate switch determines if air is added to the tires or re-
leased from the tires. When the tires are being inflated, an
indicator light on the instrument panel illuminates. If the pres-
sure in any of the tires drops to 8 psi (55 kPa) or below, the low
pressure indicator light will illuminate and an alarm will
sound. If the tire pressure ever exceeds 55 psi (379 kPa), a re-
lief valve automatically relieves any excess pressure. The tire
selector valve position determines whether the pressure in the
front, rear or all four tires will be adjusted. The air pressure
gauge indicates the current pressure in the tires. Refer to the
short, white needle for front tire pressure and the longer, or-
ange needle for the pressure in the rear tires. Temperature rise
and fall affects air pressure in a tire. As the vehicle is operated
it is typical for the air pressure to rise 3-5 psi (21-34 kPa). As
the wheels and tires cool down, the air pressure will drop. This
is normal and such a drop in tire pressure does not indicate any
leaks in the system.

The CTIS consists of an electric air compressor that pumps air
through a series of valves, tubes, and hoses to the front and/or
rear tires. Compressed air travels through the manifold where
three electric valves connected in parallel direct the com-
pressed air to the front, rear or both tires. When deflation is se-
lected, air is routed from the tires through the three electric
valves and is exhausted through the deflate valves
(Figure 6-49).

Each wheel assembly has a manual quick-disconnect valve
which can be used to prevent air flow to and from the tire, such
as during long-term storage or while changing a tire. If the ve-
hicle will remain dormant for two weeks or more, it is a good
practice to disconnect the system at the wheels. These quick-
disconnect valves are also used to restrict air flow to the opera-
tional tires when the driver wants to direct air flow to a dam-
aged tire. For example, if a tire has a small puncture and has a
leak, the quick-disconnect valves on the operational tires can
be disconnected, enabling compressed air to be directed exclu-
sively to the leaking tire. This may maintain enough tire pres-
sure in the leaking tire to allow the driver to get the vehicle to
an appropriate location for safe tire repair or replacement
(Figure 6-50).

Figure 6-49: Central Tire Inflation System (CTIS)

Figure 6-50: Quick-Disconnect Valve

To disconnect the CTIS from the wheel assemblies, first turn
inflate/deflate switch to the OFF position. Release the four
quick-disconnect valve assemblies from all four spindles by
depressing the quick-disconnect valve tabs attached to the
valve spindle nuts (Figure 6-51). When the tabs are depressed,
the valve assemblies will spring away from the spindles about
1/2 inch (12.7 mm). To reconnect the quick-disconnect valve
assemblies, push the valve assemblies toward the spindles until
they click into place.

RADIAL TIRE

WHEEL

QUICK

DISCONNECT

SPINDLE

HALFSHAFT

AIR SEAL

FROM

FITTING

PASSAGE

COMPRESSOR

1-PIECE

RUNFLAT

BEADLOCK

SPINDLE

TUBE SHIELD

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