Hummer H1 (2002+). Manual - part 117

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Brake System 7-27

05745159

Installation

Install boot on body. Install upper boot on parking brake
hand lever.

Install parking brake hand lever on body and secure with
two washers, bolts, washers, and locknuts.

Secure parking brake hand lever on body with bolt, nut
and lockwasher assembly, wiring harness clamp, and nut
and lockwasher assembly.

Secure parking brake hand lever on body with three bolts,
washers, and locknuts.

Apply parking brake hand lever and tighten three bolts to
96 lb-in. (11 N•m).

Install clevis on bellcrank with clevis pin, washer, and
cotter pin (Figure 7-32).

Figure 7-32: Parking Brake Rod Attachment at Hand

Lever

Install six clips and close lower boot.

Install parking brake switch.

Adjust parking brake lever.

Figure 7-33: Parking Brake Hand Lever Mounting

FRONT DISC BRAKE CALIPER REPAIR

Disassembly

Remove disc brake caliper.

Insert wood block between jaw of caliper and piston
(Figure 7-34).

WARNING: To avoid injury, hold caliper so piston is
facing away from your body and keep fingers out of
space between piston and wood block. Compressed air
used for cleaning should not exceed 30 psi (207 kPa).

Remove piston from caliper by applying air pressure to
hose inlet of caliper.

Remove piston dust boot and seal from caliper bore.
Discard dust boot and seal (Figure 7-35).

Remove bleeder screw from caliper.

Cleaning and Inspection

NOTE:

Clean all components, examine for wear or damage,

and replace if necessary (Figure 7-35).

Inspect caliper bore for scoring, nicks, or corrosion. Minor
corrosion can be polished with abrasive crocus cloth or
hone. Replace caliper if bore is not repairable.

Inspect piston outside diameter for scoring, nicks,
corrosion, and worn or damaged chrome plating. Replace
piston if there are any surface defects.

Inspect bleeder screw for damage or stripped threads.
Replace if damaged.

Inspect bushing for damage. Replace if damaged.

CLIP

BOOT

BELLCRANK

CLEVIS PIN

CLEVIS

LOWER

PARKING BRAKE LEVER

WIRING HARNESS CLAMP

BODY

UPPER BOOT

7-28

Brake System

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Figure 7-34: Front Disc Brake Caliper

Assembly

CAUTION:

The HUMMER is equipped with DOT 3 fluid.

not mix with other brake fluids

. Failure to use the proper

brake fluid will damage brake system.

Lubricate caliper bore and seal with DOT 3 brake fluid
(Figure 7-35).

Install seal in groove of caliper bore.

Lubricate piston with DOT 3 brake fluid install dust boot
on piston.

Work piston and dust boot into caliper bore.

Seat dust boot in caliper.

Install bleeder screw in caliper finger tight.

Lubricate caliper guide pins, sleeves and adapter slides

with Permatex

Ultra Disc Brake Caliper Lube

(Permatex PN 20356) prior to installation.

Install disc brake caliper.

Figure 7-35: Front Disc Brake Caliper Assembly

HOSE

INLET

CALIPER

BLEEDER

SLEEVE

BUSHING

CALIPER BORE

CALIPER

SEAL

PISTON

PISTON DUST BOOT

SCREW

4-1-00

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Brake System 7-29

05745159

REAR CALIPER OVERHAUL

Rear Caliper Disassembly (Figure 7-37)

Mount caliper in vise so parking brake lever and spring are
facing upward.

Unseat and remove parking brake lever spring. Use large slip
joint pliers.

Remove bolt that secures lever retainer to thrust screw.
Then remove retainer, but do not remove parking brake
lever at this time.

Remove caliper piston as follows:

a. Remove piston retaining screw with hex key and pencil

magnet. Use magnet to withdraw screw after loosening
it.

b. Extend piston by rotating parking brake lever.

c. Rotate caliper piston in counter-clockwise direction un-

til it comes off thrust screw. Rotate piston by hand, or
use piston retraction tool J-42553 (Figure 7-36).

Figure 7-36: Piston Removal

d. Pull piston out of dust boot and remove it from caliper.

Remove piston dust boot with pry tool.

CAUTION: Exercise care when removing the boot. Do not al-
low the pry tool to scratch the caliper piston bore.

Remove thrust screw retaining ring. Carefully unseat ring
with long, thin, flat blade screwdriver. Apply single wrap
of electrical tape around screwdriver blade to avoid
scratching bore, or thrust screw spring shield.

Grasp thrust screw and slide screw, shield, and spring out
of bore as assembly. Rotate brake lever to assist removal.

Remove parking brake lever from actuator shaft.

Remove actuator shaft bearing balls with pencil magnet.

10. Remove thrust screw centering pin plug and spacer. Then

reach inside caliper piston bore and push centering pin out
of caliper with finger pressure.

11. Push bearing plate and actuator shaft out of caliper bore

using finger pressure.

12. Remove caliper piston seal from groove in piston bore.

Use wood pencil to remove seal. Do not use metal tools
that will scratch bore.

13. Remove and discard actuator shaft dust seal. Discard seal.

14. Remove and discard centering pin plug O-ring.

15. Remove and discard centering pin O-ring.

16. Remove O-ring from actuator shaft. Then remove thrust

bearing and race from shaft. Discard O-ring but retain
bearing and race if in good condition.

17. Disassembly caliper piston as follows:

a. Remove retaining ring with internal type ring pliers.

b. Remove wave washer.

c. Remove thrust washer and bearing.

d. Remove cone clutch.

Caliper Cleaning and Inspection

Clean the caliper parts in standard parts cleaning solvent, or
denatured alcohol. Dry the parts with compressed air or lint
free shop towels.

Replace the caliper piston if corroded, rusted, or scored. Do not
attempt to salvage any piston where rust or scoring has broken
through the piston plating. Also, do not use any type of abra-
sive material on the piston surface. This practice will damage
the plating and cause the piston to stick or seize in the bore.

Check condition of the caliper piston bore. Moderate surface
discoloration is normal and not a cause for replacement. How-
ever, the caliper should be replaced if the bore is corroded, pit-
ted, or scored. The bore can be lightly polished with crocus
cloth but must not be honed or sanded.

Inspect the thrust screw and actuator shaft parts. Replace the
thrust screw, spring shield, and retaining ring if damaged, or
distorted. Replace the actuator shaft, bearing plate, and bearing
balls if scored, cracked, worn, corroded, or pitted. Also replace
the shaft bearing and race as a set if either part is worn, rough,
pitted, or scored.

Replace the caliper piston cone clutch, bearing and race, or
wave washer if worn, scored, or damaged.

Assembly (Figure 7-37)

Install new actuator shaft dust seal in caliper. Use one-inch
socket to seat seal in housing. The open portion of seal
metal retainer faces out. Lubricate seal lip with DOT 3
brake fluid afterward.

Lubricate actuator shaft, bearings, race, and plate with
DOT 3 brake fluid. Then install thrust bearing and race on
shaft and secure with new O-ring.

Install actuator shaft in caliper. Then install plastic bearing
plate and the three ball bearings.

Install new O-ring on thrust screw centering pin and install
pin in caliper. Position pin so blade will align with slot in
thrust screw.

Lubricate thrust screw with DOT 3 brake fluid. Then install
spring and retaining ring on thrust screw.

DISC BRAKE

RETRACTION

TOOL

PISTON

CALIPER

PISTON

J-42553

7-30

Brake System

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Install thrust screw as follows:

a. Align slot in thrust screw with centering pin.

b. Insert thrust screw in caliper and seat it on centering pin

and on ball bearings.

c. Compress thrust screw retaining ring with fingers and

install it in caliper bore below piston seal groove.

CAUTION: Do not use metal tools to install the retaining ring.
Metal tools will score or scratch the caliper bore.

d. Push assembly into bore as far as possible.

e. Seat retaining ring using unassembled caliper piston.

Lightly coat piston with DOT 3 brake fluid and insert it
in bore. Then push piston sharply downward two or
three times to seat retaining ring. Remove piston after
ring is seated.

Install new O-ring on centering pin plug. Then position
spacer on top of centering pin and install plug. Tighten
plug securely with hex wrench or socket.

Install new caliper piston seal. Start square cut seal into
groove at top of bore and work it into place with your
fingers. Lubricate seal and bore with fresh DOT 3 brake
fluid.

Assembly caliper piston as follows;

a. Install cone clutch in piston.

b. Lubricate bearing and race with DOT 3 brake fluid and

install them on cone clutch. The open side of bearing
goes toward race.

c. Install wave washer (either side up).

d. Install retaining ring with internal-type ring pliers. Flat

side of ring goes toward wave washer.

10. Install caliper piston as follows:

a. Install new dust boot on caliper piston.

b. Lubricate caliper piston with fresh brake fluid. Then in-

sert it through dust boot, into caliper bore, and onto
thrust screw.

c. Install parking brake lever on actuator shaft and rotate

lever to extend thrust screw.

d. Rotate piston onto thrust screw by hand, then with suit-

able size socket.

e. Turn parking lever to normal (non-applied) position and

complete piston installation as needed.

f. Seat piston dust boot in groove at top of caliper bore.

Use suitable size boot installer tool or flat punch.

11. Install new O-ring on piston retaining screw and install

screw. Tighten screw securely.

12. Install parking brake lever retainer and bolt. Apply 1-2

drops Loctite to bolt threads before installation.

13. Install and seat parking brake lever return spring in cable

housing slot.

14. Install bleed screw, if removed Apply anti-seize

compound to screw threads beforehand.

Content .. 115 116 117 118 ..