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Home >> Chevrolet >> 2007 >> Optra5 LS, Standard >> Repair and Diagnosis (Single Page) >> Brakes >> Mechanical - Hydraulic >> Disc Brakes >> Diagnostic Information and Procedures >> Brake Rotor Surface and Wear Inspection >> Rear Rotor Inspection Procedure

Rear Rotor Inspection Procedure

Fig 1: Measuring Thickness Of Rotor
GM1255713Courtesy of GENERAL MOTORS CORP.

Measure the thickness of the rotor at 4 or more points around the circumference of the rotor at the same distance in form the edge of the rotor. A new rotor is 10.4 mm (0.95 in) thick. Discard the rotor if the thickness is 8 mm (0.31 in) or less.

Rotor thickness that varies by more than 0.01 mm (0.0004 in) can cause brake pedal pulsation and/or rear brake vibration during brake applications. A rotor that does not meet these specifications should be refinished to specifications or replaced.

Using a commercially available dial indicator, measure the lateral runout of the rear brake rotor as follows:

  1. Position the shift lever in NEUTRAL.
  2. Raise and support the vehicle. Refer to Lifting and Jacking the Vehicle .
  3. To preserve the wheel balance, mark the relative positions of the wheel and the hub.
  4. Remove the rear tire and wheel assembly. Refer to Tire and Wheel Removal and Installation .
  5. Remove the rotor. Refer to Rear Brake Rotor Replacement .
  6. Clean the rotor.
  7. Clean the hub.
  8. Verify the hub-to-rotor contact surfaces are smooth and free from burrs.
  9. Fasten the brake rotor to the wheel hub.
  10. Fig 2: View Of Dial Indicator With Probe Tip 10mm From Edge Of Rotor
    GM1255712Courtesy of GENERAL MOTORS CORP.
  11. Mount the dial indicator.
  12. Place the indicator tip approximately 10 mm (0.39 in) from the outer edge of brake rotor, perpendicular to the disc and under slight preload.
  13. Rotate the rotor and observe the indicator gage.
  14. Determine the lateral runout of the rotor.

    Specification:  The maximum allowable lateral runout of the rear installed on the vehicle is 0.08 mm (0.003 in).

  15. Remove the dial indicator.
  16. If necessary, refinish the rotor with precision equipment.
  17. Complete the installation of the rotor. Refer to Rear Brake Rotor Replacement .
  18. Align the marks that were made before the wheel removal, and install the rear tire and wheel assembly. Refer to Tire and Wheel Removal and Installation .
  19. Lower the vehicle.