Hummer H3. Manual — part 1040

Fig. 7: View Of Brake Pads & Audible Wear Sensors
Courtesy of GENERAL MOTORS CORP.

Inspect the disc brake pads at regular intervals or whenever the tire and wheel assemblies
are removed from the vehicle.

If replacement is necessary, always replace disc brake pads in axle sets.

Inspect both edges of the disc brake pad friction surfaces (3). The highest rate of wear
normally occurs at the trailing edge of the disc brake pads.

Inspect the thickness of the disc brake pads (3) in order to ensure that they have not worn
prematurely. The disc brake pad wear should be approximately even per axle set.

Both front and rear disc brake pads have integral, audible wear sensors (1). When the disc
brake pad wear reaches the minimum allowable thickness, the wear sensor contacts the disc
brake rotor (2). The wear indicator will then produce an audible, high-pitched warning
noise during wheel rotation.

Replace the disc brake pads when the friction surface (3) is worn to within 0.76 mm (0.030
in) of the mounting plates.

Remove the brake calipers and inspect the friction surfaces of the inner and outer disc brake
pads to ensure that they are level. Place the disc brake pad friction surfaces together and
measure the gap between the surfaces. If more than 0.13 mm (0.005 in) gap exists midway
between the length of the disc brake pads, replace the disc brake pads.

Verify that any disc brake pad shims that may be required are in place and not damaged or
excessively corroded. Replace any missing or damaged shims in order to preserve proper
disc brake performance.

Replace the disc brake pads if any have separated from the mounting plates.

Inspect the disc brake pads friction surfaces for cracks, fractures or damage which may
cause noise or otherwise impair disc brake performance.

BRAKE CALIPER INSPECTION

CAUTION: Refer to Brake Dust Caution .

2007 Hummer H3

2007 BRAKES Disc Brakes - H3

Fig. 8: Exploded View Of Brake Caliper
Courtesy of GENERAL MOTORS CORP.

1. Inspect the brake caliper housing (1) for cracks, excess wear, and/or damage. If any of these

conditions are present, the brake caliper requires replacement.

2. Inspect the caliper piston dust boot seal (2) for cracks, tears, cuts, deterioration and/or

improper seating in the caliper body. If any of these conditions are present, the brake caliper
requires overhaul or replacement.

3. Inspect for brake fluid leakage around the caliper piston dust boot seal (2) and on the disc

2007 Hummer H3

2007 BRAKES Disc Brakes - H3

brake pads. If there is any evidence of brake fluid leakage, the brake caliper requires
overhaul or replacement.

Fig. 9: Compressing Caliper Piston
Courtesy of GENERAL MOTORS CORP.

4. Inspect for smooth and complete travel of the caliper pistons into the caliper bores:

The movement of the caliper pistons into the caliper bores should be smooth and even. If the
caliper piston is frozen or difficult to bottom, the caliper requires overhaul or replacement.

For single piston caliper applications, insert a discarded inner brake pad (2) or block

2007 Hummer H3

2007 BRAKES Disc Brakes - H3

of wood in front of the piston. Using a large C-clamp (1) installed over the body of the
caliper (3) and against the brake pad or block of wood, slowly bottom the piston in the
bore.

For dual piston caliper applications, insert a discarded inner brake pad (2) or block of
wood in front of the pistons. Using 2 large C-clamps (1) installed over the body of the
caliper (3) and against the brake pad or block of wood, slowly bottom the pistons
evenly into the bores.

FRONT DISC BRAKE MOUNTING AND HARDWARE INSPECTION

1. Inspect the fluid level in the brake master cylinder reservoir.

2. If the brake fluid level is midway between the maximum-full point and the minimum

allowable level, then no brake fluid needs to be removed from the reservoir before
proceeding.

3. If the brake fluid level is higher than midway between the maximum-full point and the

minimum allowable level, then remove brake fluid to the midway point before proceeding.

4. Raise and support the vehicle. Refer Lifting and Jacking the Vehicle .

5. Remove the tire and wheel assembly. Refer to Tire and Wheel Removal and

Installation .

CAUTION: Refer to Brake Dust Caution .

2007 Hummer H3

2007 BRAKES Disc Brakes - H3