Hummer H3. Manual — part 1037

Fig. 1: Measuring Brake Rotor Thickness
Courtesy of GENERAL MOTORS CORP.

1. Clean the brake pad lining contact surface of the brake rotor with denatured alcohol or an

equivalent brake cleaner.

2. Using a calibrated micrometer measure and record the lowest thickness of the brake rotor at

2007 Hummer H3

2007 BRAKES Disc Brakes - H3

4 or more points equally spaced around the rotor.

Ensure that the measurements are only taken within the brake pad lining contact area and
that the micrometer is positioned the same distance from the outside edge of the rotor for
each measurement.

3. If the lowest thickness measurement of the brake rotor is above the minimum allowable

thickness after refinishing specification, the rotor may be able to be refinished, depending
upon surface and wear conditions which may be present.

4. If the lowest thickness measurement of the brake rotor is at or below the minimum

allowable thickness after refinishing specification, the rotor may not be refinished.

5. If the lowest thickness measurement of the brake rotor is at or below the discard thickness

specification, the rotor requires replacement.

BRAKE ROTOR THICKNESS VARIATION MEASUREMENT

1. If the inboard friction surface of the brake rotor is not accessible, reposition and support the

caliper with the brake pads. Refer to Front Disc Brake Pads Replacement and/or Rear
Disc Brake Pads Replacement.

2. Clean the friction surfaces of the brake rotor with denatured alcohol or an equivalent

approved brake cleaner.

CAUTION: Refer to Brake Dust Caution .

IMPORTANT: Any disc brake rotor that exhibits thickness variation exceeding

the maximum acceptable level must be refinished or replaced.
Thickness variation exceeding the maximum acceptable level can
cause brake pulsation.

2007 Hummer H3

2007 BRAKES Disc Brakes - H3

Fig. 2: Measuring Brake Rotor Thickness
Courtesy of GENERAL MOTORS CORP.

3. Using a micrometer calibrated in thousandths-of-a-millimeter or ten-thousandths-of-an-inch,

measure and record the thickness of the brake rotor at 4 or more points, evenly spaced
around the rotor.

2007 Hummer H3

2007 BRAKES Disc Brakes - H3

Ensure that the measurements are only taken within the friction surfaces and that the
micrometer is positioned the same distance from the outer edge of the rotor, about 13 mm
(1/2 in), for each measurement.

4. Calculate the difference between the highest and lowest thickness measurements recorded to

obtain the amount of thickness variation.

5. Compare the thickness variation measurement to the following specification:

Specification: Brake rotor maximum allowable thickness variation: 0.025 mm (0.001 in)

6. If the brake rotor thickness variation measurement exceeds the specification, the rotor

requires refinishing or replacement.

BRAKE ROTOR SURFACE AND WEAR INSPECTION

1. If the inboard friction surface of the brake rotor is not accessible, reposition and support the

caliper with the brake pads. Refer to Front Disc Brake Pads Replacement and/or Rear
Disc Brake Pads Replacement.

2. Clean the friction surfaces of the brake rotor with denatured alcohol or an equivalent

approved brake cleaner.

3. Inspect the friction surfaces of the brake rotor for the following Braking Surface

Conditions:

Heavy rust and/or pitting

Light surface rust can be removed with an abrasive disc. Heavy surface rust and/or
pitting must be removed by refinishing the rotor.

Cracks and/or heat spots

Excessive blueing discoloration

4. If the friction surfaces of the brake rotor exhibit one or more of the Braking Surface

Conditions, the rotor requires refinishing or replacement.

IMPORTANT: Whenever a brake rotor is refinished or replaced, the

assembled lateral runout (LRO) of the rotor must be
measured to ensure optimum performance of the disc
brakes.

CAUTION: Refer to Brake Dust Caution .

2007 Hummer H3

2007 BRAKES Disc Brakes - H3