GM Service Manual Online
For 1990-2009 cars only

Tools Required

    • J 26900-12 Dial Indicator
    • J 26900-13 Magnetic Indicator Base
    • J 23738-A Hand Vacuum Pump

Caution: Refer to Safety Glasses Caution in the Preface section.

Caution: Refer to Vehicle Lifting Caution in the Preface section.

Caution: Refer to Brake Dust Caution in the Preface section.

Important: 

   • Brake disc assembled lateral runout (LRO) exceeding the maximum allowable specification can cause thickness variation to develop in the brake disc over time, usually between 10,000 [dash ] 20,000 km (6,200 [dash ] 12,400 mi).
   • Brake disc thickness variation MUST be inspected BEFORE inspecting for assembled LRO. Thickness variation exceeding the maximum acceptable level can cause brake pulsation. Refer to Brake Rotor Thickness Variation Measurement .

  1. Matchmark the position of the brake disc to the wheel studs.
  2. Important: Whenever the brake disc has been separated from the hub/axle flange, any rust or contaminants should be cleaned from the hub/axle flange and the brake disc mating surfaces. Failure to do this may result in too much assembled LRO of the brake disc, which may lead to brake pulsation.

  3. Inspect the mating surface of the hub/axle flange and the brake disc to make sure that there is no corrosion, foreign particles, rust, or debris. If the wheel hub/axle flange and/or brake disc mating surfaces exhibit these conditions, perform the following steps:
  4. 2.1. Remove the brake disc from the vehicle. Refer to Front Brake Rotor Replacement or Rear Brake Rotor Replacement .
    2.2. Clean any rust or corrosion from the mating surface of the hub/axle flange.
    2.3. Clean any rust or corrosion from the mating surface of the brake disc.
    2.4. Clean the friction surfaces of the brake disc with denatured alcohol, or an equivalent approved brake cleaner.
  5. Install the disc to the hub/axle flange using the matchmark made prior to removal.
  6. Important: Install the wheel nuts in reverse avoid damage to the tapers.

  7. Install 2 wheel nuts in reverse to opposite wheel studs to retain the brake disc to the hub.
  8. Mount a dial indicator and position the indicator button so it contacts the brake disc friction surface at a 90 degree angle, approximately 10 mm (3/8 in) from the outer edge of the brake disc.

  9. Object Number: 1960735  Size: SF

       Important: The dial indicator's magnetic mounting base (4) must be securely mounted to the front strut unit (5).

    • To measure the front brake disc assembled LRO (View A), set up a dial indicator (2) on a magnetic mounting base (4) and attach to the front strut unit (5) above the brake disc (1).

       Important: The dial indicator's magnetic mounting base (3) must be securely mounted to the dial indicator plate (2).

    • To measure the rear brake disc assembled LRO (View B), bolt the dial indicator plate (2) to the brake caliper attaching points on the rear knuckle. Set up a dial indicator (4) on a magnetic mounting base (3) and attach to the dial indicator plate (2). Refer to Dial Indicator Plate in Special Tools for dial indicator plate details.
  10. Measure and record the assembled LRO of the brake disc:
  11. 6.1. Rotate the brake disc until the lowest reading is displayed on the indicator dial, then set the dial to zero.
    6.2. Rotate the brake disc until the highest reading is displayed on the dial.
    6.3. Mark the location of the high spot relative to the nearest wheel stud, or studs.
    6.4. Measure and record the amount of assembled LRO.
  12. Compare the brake disc assembled LRO to the following specification:
  13. Specification

        • Front brake disc maximum allowable assembled lateral runout: 0.05 mm (0.002 in).
        • Rear brake disc maximum allowable assembled lateral runout: 0.05 mm (0.002 in).
  14. If the brake disc assembled LRO measurement exceeds the specification, refer to Brake Rotor Assembled Lateral Runout Correction .
  15. If the brake disc assembled LRO measurement is within specification, install the brake caliper and depress the brake pedal several times to secure the brake disc in place before removing the wheel nuts.