Hummer H3. Manual — part 1051

Fig. 32: Mounting Dial Indicator To Measure Lateral Runout
Courtesy of GENERAL MOTORS CORP.

10. Mount a dial indicator, J 45101 or equivalent, to the steering knuckle and position the

indicator button so it contacts the brake rotor friction surface at a 90 degree angle,
approximately 13 mm (0. See Special Tools.5 in) from the outer edge of the rotor.

11. Measure and record the assembled LRO of the brake rotor.

1. Rotate the rotor until the lowest reading is displayed on the indicator dial, then set the

dial to zero.

2. Rotate the rotor until the highest reading is displayed on the dial.

3. Mark the location of the high spot relative to the nearest wheel stud or studs.

4. Measure and record the amount of LRO.

12. Compare the brake rotor assembled LRO to the following specification:

Specification:

Front brake rotor maximum allowable assembled lateral runout: 0.13 mm (0.005 in)

Rear brake rotor maximum allowable assembled lateral runout: 0.13 mm (0.005 in)

13. If the brake rotor assembled LRO is within specifications, proceed to step 18.

If the brake rotor assembled LRO exceeds the specification, refinish the rotor to ensure true
parallelism, refer to Brake Rotor Refinishing. After refinishing the rotor, proceed to step
14.

14. Mount a dial indicator, J 45101 or equivalent, to the steering knuckle and position the

indicator button so it contacts the brake rotor friction surface at a 90 degree angle,
approximately 13 mm (0. See Special Tools.5 in) from the outer edge of the rotor.

15. Measure and record the assembled LRO of the brake rotor.

1. Rotate the rotor until the lowest reading is displayed on the indicator dial, then set the

dial to zero.

2. Rotate the rotor until the highest reading is displayed on the dial.

3. Mark the location of the high spot relative to the nearest wheel stud or studs.

4. Measure and record the amount of LRO.

16. Compare the brake rotor assembled LRO to the following specification:

Specification:

Front brake rotor maximum allowable assembled lateral runout: 0.13 mm (0.005 in)

2007 Hummer H3

2007 BRAKES Disc Brakes - H3

Rear brake rotor maximum allowable assembled lateral runout: 0.13 mm (0.005 in)

17. If the brake rotor assembled LRO measurement exceeds the specification, bring the LRO to

within specifications. Refer to Brake Rotor Assembled Lateral Runout Correction.

18. If the brake rotor assembled LRO measurement is within specification, install the brake

caliper and depress the brake pedal several times to secure the rotor in place before
removing the J 45101-100 and the lug nuts. See Special Tools.

BRAKE ROTOR REFINISHING

Tools Required

J 41013 Rotor Resurfacing Kit. See Special Tools.

J 42450-A Wheel Hub Resurfacing Kit. See Special Tools.

CAUTION: Refer to Brake Dust Caution .

IMPORTANT:

The disc brake rotors do not require refinishing as part of
routine brake system service. New disc brake rotors do not
require refinishing.

Do not refinish disc brake rotors in an attempt to correct the
following conditions:

Brake system noise - squeal, growl, groan

Uneven and/or premature disc brake pad wear

Superficial or cosmetic corrosion/rust of the disc brake
rotor friction surface

Scoring of the disc brake rotor friction surface less than
the maximum allowable specification

Before refinishing a brake rotor, the rotor MUST first be
checked for adequate thickness to allow the rotor to be
refinished and remain above the minimum allowable
thickness after refinish specification. Refer to Brake Rotor
Thickness Measurement.

Disc brake rotors should only be refinished if they have

2007 Hummer H3

2007 BRAKES Disc Brakes - H3

Procedure

1. Using the J 42450-A , thoroughly clean any rust or corrosion from the mating surface of the

hub/axle flange. See Special Tools.

2. Using the J 41013 , thoroughly clean any rust or corrosion from the mating surface and

mounting surface of the brake rotor.

3. Inspect the mating surfaces of the hub/axle flange and the rotor to ensure that there are no

foreign particles or debris remaining.

4. Mount the brake rotor to the brake lathe according to the lathe manufacturer's instructions,

ensuring that all mounting attachments and adapters are clean and free of debris.

5. Ensure that any vibration dampening attachments are securely in place.

6. With the brake lathe running, slowly bring in the cutting tools until they just contact the

brake rotor friction surfaces.

7. Observe the witness mark on the brake rotor. If the witness mark extends approximately

three-quarters or more of the way around the brake rotor friction surface on each side, the
brake rotor is properly mounted to the lathe.

8. If the witness mark does not extend three-quarters or more of the way around the brake

adequate thickness to be refinished and if one or more of the
following conditions exist:

Thickness variation in excess of the maximum allowable
specification

Excessive corrosion/rust and/or pitting

Cracks and/or heat spots

Excessive blueing discoloration

Scoring of the disc brake rotor surface in excess of the
maximum allowable specification

Disc brake rotors may need to be refinished as part of the
process for correcting brake rotor assembled lateral runout
(LRO) that exceeds the maximum allowable specification.

IMPORTANT: Whenever the brake rotor has been separated from the

hub/axle flange, clean any rust or contaminants from the
hub/axle flange and the brake rotor mating surfaces. Failure
to do this may result in increased assembled lateral runout
(LRO) of the brake rotor, which could lead to brake pulsation.

2007 Hummer H3

2007 BRAKES Disc Brakes - H3

rotor, re-mount the rotor to the lathe.

9. Following the brake lathe manufacturer's instructions, refinish the brake rotor.

10. After each successive cut, inspect the brake rotor thickness. Refer to Brake Rotor

Thickness Measurement.

11. If at any time the brake rotor exceeds the minimum allowable thickness after refinish

specification, the brake rotor must be replaced.

12. After refinishing the brake rotor, use the following procedure in order to obtain the desired

non-directional finish:

1. Follow the brake lathe manufacturer's recommended speed setting for applying a non-

directional finish.

2. Using moderate pressure, apply the non-directional finish:

If the lathe is equipped with a non-directional finishing tool, apply the finish with
120 grit aluminum oxide sandpaper.

If the lathe is not equipped with a non-directional finishing tool, apply the finish
with a sanding block and 150 grit aluminum oxide sandpaper.

3. After applying a non-directional finish, clean each friction surface of the brake rotor

with denatured alcohol or an equivalent approved brake cleaner.

13. Remove the brake rotor from the brake lathe.

14. Measure the assembled lateral runout (LRO) of the brake rotor to ensure optimum

performance of the disc brakes. Refer to Brake Rotor Assembled Lateral Runout
Measurement.

15. If the brake rotor assembled LRO measurement exceeds the specification, bring the LRO to

within specifications. Refer to Brake Rotor Assembled Lateral Runout Correction.

DESCRIPTION AND OPERATION

DISC BRAKE SYSTEM DESCRIPTION AND OPERATION

System Component Description

The disc brake system consists of the following components:

Disc Brake Pads

Applies mechanical output force from the hydraulic brake calipers to friction surfaces of
brake rotors.

Disc Brake Rotors

2007 Hummer H3

2007 BRAKES Disc Brakes - H3