Hummer H3. Manual — part 1570

Fig. 57: Identifying Park Brake Cable Adjustment Nut
Courtesy of GENERAL MOTORS CORP.

1. Fully apply and release the park brake lever with an operating force equivalent to the

specification 10 times to settle the front park brake cable.

Specification: 490 N (108 lb)

2. Turn ON the ignition. Verify the red BRAKE warning lamp is not illuminated.

3. Turn OFF the ignition.

4. Remove the driver knee bolster bracket. Refer to Driver Knee Bolster Replacement

(Left Hand Drive) or Driver Knee Bolster Replacement (Right Hand Drive) .

5. Loosen the front park brake cable adjustment nut (1).

6. Raise and support the vehicle. Refer to Lifting and Jacking the Vehicle .

7. Verify both rear wheel and tire assemblies rotate freely with no drag.

2007 Hummer H3

2007 BRAKES Park Brake - H3

8. Apply the brake lever to 8 notches.

9. Tighten the front park brake cable adjustment nut until it contacts the park brake lever.

10. Fully release the park brake lever.

11. Verify both rear wheel and tire assemblies rotate freely with no drag.

12. Apply the park brake lever with an operating force equivalent to the specification to 8

notches.

Specification: 294 N (64 lb)

13. Attempt to rotate the rear wheel and tire assemblies.

14. The rear wheel and tire assemblies should not rotate.

15. If the rear tire and wheel assemblies rotate, repeat the adjustment procedure.

16. Fully release the park brake lever.

17. Verify both rear wheel and tire assemblies rotate freely with no drag.

18. Lower the vehicle.

19. Install the driver knee bolster bracket. Refer to Driver Knee Bolster Replacement (Left

Hand Drive) or Driver Knee Bolster Replacement (Right Hand Drive) .

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.

2007 Hummer H3

2007 BRAKES Park Brake - H3

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 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

2007 Hummer H3

2007 BRAKES Park Brake - H3

J 21177-A

Drum-to-Brake Shoe Clearance Gage

2007 Hummer H3

2007 BRAKES Park Brake - H3