Hummer H2. Manual — part 825

Tools Required

J 21177-A Drum-to-Brake Shoe Clearance Gauge. See Special Tools and Equipment .

Park Brake Shoe Adjustment

Fig. 52: Applying J 21177-A To Inside Of Brake Drum
Courtesy of GENERAL MOTORS CORP.

1. Set the J 21177-A so that it contacts the inside diameter of the rotor (1). See Special Tools and

IMPORTANT: The park brake shoes must be adjusted before the park brake pedal is

adjusted.

2004 Hummer H2

2004 BRAKES Park Brake - Hummer H2

Equipment .

Fig. 53: Adjusting Parking Brake Shoes Using J 21177-A
Courtesy of GENERAL MOTORS CORP.

2. Position the J 21177-A over the shoe (1) and the lining at the widest point. See Special Tools and

Equipment .

3. Turn the adjuster nut until the lining just contacts the J 21177-A . See Special Tools and Equipment .

4. Repeat steps 1-3 for the opposite side.

5. The clearance between the park brake shoe and the rotor is 0.6604 mm (0.026 in).

Park Brake Pedal Adjustment

2004 Hummer H2

2004 BRAKES Park Brake - Hummer H2

1. Verify that the automatic adjuster lock-out pin has been removed.

2. Fully apply and release the park brake pedal 3 times.

DESCRIPTION AND OPERATION

PARK BRAKE SYSTEM DESCRIPTION AND OPERATION

System Component Description

The park brake system consists of the following:

Park Brake Pedal Assembly

Receives and transfers park brake system apply input force from driver to park brake cable system.

Park Brake Release Handle Assembly

Releases applied park brake system when pulled.

Park Brake Cables

Transfers input force received from park brake pedal, through park brake cable equalizer, to park brake
apply lever.

Park Brake Cable Equalizer

Evenly distributes input force to both the left and right park brake units.
Threaded park brake cable equalizers are also used to remove slack in park brake cables.

Park Brake Apply Lever

Multiplies and transfers input force to park brake actuator.

Park Brake Actuator/Adjuster

Uses multiplied input force from apply lever to expand park brake shoe toward the friction surface of the
drum-in-hat portion of the rear brake rotor.
Threaded park brake actuators are also used to control clearance between the park brake shoe and the
friction surface of the drum-in-hat portion of the rear brake rotor.

Park Brake Shoe

Applies mechanical output force from park brake actuator to friction surface of the drum-in-hat portion of

IMPORTANT: Before you adjust the park brake, verify that the park brake shoes are adjusted

to provide a clearance of 0.6604 mm (0.026 in).

2004 Hummer H2

2004 BRAKES Park Brake - Hummer H2

the rear brake rotor.

System Operation

Park brake apply input force is received by the park brake pedal assembly being depressed, transferred and
evenly distributed, through the park brake cables and the park brake cable equalizer, to the left and right park
brake apply levers. The park brake apply levers multiply and transfer the apply input force to the park brake
actuators which expand the park brake shoe toward the friction surface of the drum-in-hat portion of the rear
brake rotor in order to prevent the rotation of the rear tire and wheel assemblies. The park brake release handle
assembly releases an applied park brake system when it is pulled rearward.

SPECIAL TOOLS AND EQUIPMENT

SPECIAL TOOLS

Special Tools

Illustration

Tool Number/Description

J 21177-A

Drum-to-Brake Shoe Clearance Gauge

2004 Hummer H2

2004 BRAKES Park Brake - Hummer H2