Hummer H1 (2006+). Manual - part 239

7-38

Brake System

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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 bear-
ing 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)

1.

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

2.

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

3.

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

4.

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

5.

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

6.

Install the thrust screw as follows:

a.

Align the slot in the thrust screw with the centering pin. 

b.

Insert the thrust screw in the caliper and seat it on the centering pin and on the ball bearings. 

c.

Compress the thrust screw retaining ring with fingers and install it in the caliper bore below the 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 the assembly into the bore as far as possible. 

e.

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

7.

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

8.

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

9.

Assembly the caliper piston as follows; 

a.

Install the cone clutch in the piston. 

b.

Lubricate the bearing and race with DOT 3 brake fluid and install them on the cone clutch. The open side of the bearing
goes toward the race. 

c.

Install the wave washer (either side up). 

d.

 Install the retaining ring with internal-type ring pliers. Flat side of the ring goes toward the wave washer. 

10. Install the caliper piston as follows:

a.

Install the new dust boot on the caliper piston. 

b.

Lubricate the caliper piston with fresh brake fluid. Then insert it through the dust boot, into the caliper bore, and onto the
thrust screw.

c.

Install the parking brake lever on the actuator shaft and rotate the lever to extend the thrust screw. 

d.

Rotate the piston onto the hrust screw by hand, then with a suitable size socket. 

e.

Turn the parking lever to normal (non-applied) position and complete the piston installation as needed. 

f.

Seat the piston dust boot in the groove at the top of the caliper bore. Use a suitable size boot installer tool or a flat punch.

11. Install a new O-ring on the piston retaining screw and install the screw. Tighten the screw securely. 

12. Install the parking brake lever retainer and the bolt. Apply 1-2 drops of Loctite to the bolt threads before installation. 

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

14. Install the bleed screw, if removed Apply anti-seize compound to the screw threads beforehand.  

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 Brake System  7-39

5745804

Figure 7-37:   Rear Caliper

O-RING

 O-RING

BLEEDER SCREW CAP

BLEEDER SCREW

ACTUATOR SHAFT

DUST SEAL

LEVER

SPRING

THRUST SCREW

RETAINING RING

THRUST SCREW

SPRING SHIELD

THRUST SCREW

SPRING

THRUST SCREW

ACTUATOR

O-RING

BEARING

THRUST

ACTUATOR SHAFT

PISTON DUST BOOT

O-RING

PISTON RETAINING SCREW

CALIPER PISTON

PISTON SEAL

SHAFT

RACE

PLUG

SPACER

THRUST SCREW

CENTERING PIN

LEVER RETAINER

AND BOOT

PARKING

BRAKE

LEVER

RETURN

CABLE

HOUSING

BEARING

ACTUATOR SHAFT 

BEARINGS

RETAINING

WAVE WASHER

BEARING RACE

CONE CLUTCH

THRUST BEARING

RING

CALIPER

BEARING PLATE

7-40

Brake System

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BRAKE ROTOR 

Removal and Inspection 

NOTE: Clean all the components, examine for wear or damage, and replace if necessary.

1.

Remove the half shaft bolts at the rotor and position the half shaft out of the way (Figure  7-38).

2.

Reinstall one of the half shaft bolts just enough so when the yoke bolts are removed the rotor does not fall (Figure  7-38).

3.

Remove the two yoke bolts and move the calliper assembly (with pads and rotor) outward enough to slide the brake pad out
from between the rotor and the caliper (Figure  7-39).

4.

Once the brake pads are out, remove the calliper from the rotor (Figure  7-39).

5.

Remove the half shaft bolt and the brake rotor.

Installation

1.

Position the inside brake pad on the brake adapter (Figure  7-39).

2.

Position the rotor to be installed on the axle flange and start a half shaft bolt just enough to keep the rotor from falling.

3.

Instal the caliper over the rotor and the inside brake pad.

4.

Slide the outside brake pad in between the rotor and the caliper.

5.

Move the caliper assembly (with pads and rotor) in to position.

6.

Secure the caliper with the two yoke bolts using medium strength loctite (blue) and tighten the bolts to 40 lb-ft (54 N.m).

7.

Remove the half shaft bolt holding the rotor in place and position the half shaft against the rotor.

NOTE: The half shaft bolts can be reused but high strength loctite (red) must be used and the nordlock washers must be replaced.

8.

Install the half shaft bolts using high strength loctite (red) and new nordlock washers, tighten the bolts to 57 lb-ft (77 N.m)
(Figure  7-38).

Figure 7-38:   Half Shaft

ROTOR

HALF SHAFT

BOLT

HALF SHAFT

NORDLOCK

WASHER

6-1-05

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 Brake System  7-41

5745804

Figure 7-39:   Front Brake Assembly

ROTOR INSPECTION 

NOTE: Clean any rusted or scaled rotor braking surfaces before attempting inspection or measurement.

1.

Mount the rotor in the brake lathe and turn while cleaning the surfaces with an abrasive crocus cloth.

2.

Inspect the rotor for heat checks, nicks, broken cooling fins, scoring, discoloration and pitting. It is not recommended that the
rotors be turned when spotted or heat checked. 

ROTOR

BRAKE

PADS

BRAKE ADAPTER

CALIPER

YOKE

YOKE

BOLT

11-1-05