Front Rotor Inspection Procedure

Measure the thickness of the rotor at 4 or more points around the circumference of the rotor, at the same distance from the edge of the rotor. A new rotor is 24 mm (0.95 in) thick. Discard the rotor if the thickness is 22 mm (0.87 in) or less.

Rotor thickness that varies by more than 0.01 mm (0.0004 in) can cause brake pedal pulsation and/or front end 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 front 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 hub.
4. Remove the front tire and wheel assembly. Refer to Tire and Wheel Removal and Installation .
5. Remove the rotor. Refer to Front 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.
Fig 1: View Of Dial Indicator With Probe Tip 10mm From Edge Of Rotor
Courtesy of GENERAL MOTORS CORP.
10. Mount the dial indicator.
11. Set the gage probe tip to approximately 10 mm (0.39 in) from the outer edge of the brake rotor, perpendicular to the disc and under slight preload.
12. Rotate the rotor and observe the indicator gage.
13. Determine the lateral runout of the rotor.

    Specification:  The maximum allowable lateral runout of the front rotor installed on the vehicle is 0.06 mm (0.002 in).

14. Remove the dial indicator.
15. Refinish the rotor, if required, with precision equipment. Discard the rotor if the rotor fails to meet the specifications after refinishing.
16. Complete the installation of the rotor. Refer to Front Brake Rotor Replacement .
17. Install the tire and wheel assembly. Refer to Tire and Wheel Removal and Installation .
18. Lower the vehicle.