Hummer H1 (2006+). Manual - part 238

7-34

Brake System

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5.

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

6.

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

.

Figure 7-32:   Parking Brake Rod Attachment at Hand Lever

7.

Install the six clips and close the lower boot.

8.

Install the parking brake switch.

9.

Adjust the parking brake lever.

Figure 7-33:   Parking Brake Hand Lever Mounting

FRONT DISC BRAKE CALIPER REPAIR

Disassembly

1.

Remove the disc brake caliper.

2.

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

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

CLIP

BOOT

BELLCRANK

CLEVIS PIN

CLEVIS

LOWER

PARKING BRAKE LEVER

WIRING HARNESS CLAMP

BODY

UPPER BOOT

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 Brake System  7-35

5745804

3.

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

4.

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

5.

Remove the bleeder screw from the caliper.

Cleaning and Inspection 

NOTE: Clean all the components, examine for wear or damage, and replace if necessary (Figure  7-35).

1.

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

2.

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

3.

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

4.

Inspect the bushing for damage. Replace if damaged.

Figure 7-34:   Front Disc Brake Caliper

Assembly

CAUTION: The HUMMER H1 is equipped with DOT 3 fluid. Do not mix with other brake fluids. Failure to use the proper brake
fluid will damage the brake system. 

1.

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

2.

Install the seal in the groove of the caliper bore. 

3.

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

4.

Work the piston and the dust boot into the caliper bore. 

5.

Seat the dust boot in the caliper.

6.

Install the bleeder screw in the caliper finger tight. 

7.

Lubricate the caliper guide pins, sleeves and the adapter slides with Permatex

®

Ultra Disc Brake Caliper Lube (Permatex PN

20356) prior to installation.

8.

Install the disc brake caliper.

HOSE

INLET

CALIPER

7-36

Brake System

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Figure 7-35:   Front Disc Brake Caliper Assembly

REAR CALIPER OVERHAUL

Rear Caliper Disassembly  (Figure  7-37)

1.

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

2.

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

3.

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

4.

Remove the caliper piston as follows:

a. Remove the piston retaining screw with hex key and pencil magnet. Use magnet to withdraw the screw after loosening it. 

b. Extend the piston by rotating the parking brake lever. 

c. Rotate the caliper piston in a counter-clockwise direction until it comes off the thrust screw. Rotate the piston by hand, or
use the piston retraction tool  J-42553 (Figure  7-36). 

BLEEDER

SLEEVE

BUSHING

CALIPER BORE

CALIPER

SEAL

PISTON

PISTON DUST BOOT

SCREW

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 Brake System  7-37

5745804

Figure 7-36:   Piston Removal

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

5.

Remove the piston dust boot with a pry tool. 

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

6.

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

7.

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

8.

Remove the parking brake lever from the actuator shaft. 

9.

Remove the actuator shaft bearing balls with a pencil magnet. 

10. Remove the thrust screw centering pin plug and the spacer. Then reach inside the caliper piston bore and push the centering

pin out of the caliper with finger pressure. 

11. Push the bearing plate and the actuator shaft out of the caliper bore using finger pressure. 

12. Remove the caliper piston seal from the groove in the piston bore. Use a wood pencil to remove the seal. Do not use metal

tools that will scratch the bore. 

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

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

15. Remove and discard the centering pin O-ring. 

16. Remove the O-ring from the actuator shaft. Then remove the thrust bearing and the race from the shaft. Discard the O-ring but

retain the bearing and the race if it is in good condition. 

17. Disassembly of the caliper piston as follows:

a.

Remove the retaining ring with internal type ring pliers. 

b.

Remove the wave washer. 

c.

Remove the thrust washer and the bearing. 

d.

Remove the 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 abrasive material on the piston surface. This practice will damage the plat-
ing 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. However, the
caliper should be replaced if the bore is corroded, pitted, or scored. The bore can be lightly polished with crocus cloth but must not
be honed or sanded. 

 DISC BRAKE

RETRACTION

 TOOL 

PISTON

CALIPER

PISTON

J-42553