Brake Rotor Thickness Variation Measurement

Special Tools

CH-45101 Hub and Wheel Runout Gauge

For equivalent regional tools, refer to Special Tools .

WARNING: Refer to Brake Dust Warning .

NOTE: 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.

If the inboard friction surface of the brake rotor is not accessible, remove the brake pads. Refer to Front Disc Brake Pads Replacement and/or Rear Disc Brake Pads Replacement , if equipped.
Clean the friction surfaces of the brake rotor with denatured alcohol or an equivalent approved brake cleaner.
Install the CH-45101 runout gauge for lateral runout measurement and compare with the correct specifications. Refer to Disc Brake Component Specifications .

Fig 1: Using Dial Indicator To Measure Lateral Runout
Courtesy of GENERAL MOTORS COMPANY

NOTE: Ensure the measurements are only taken within the friction surfaces.
If the brake rotor lateral runout measurement exceeds the specification, the rotor requires refinishing or replacement. Refer to Front Brake Rotor Replacement (15 inch Brake System J67 and J93) Front Brake Rotor Replacement (16 inch Brake System J60) , Rear Brake Rotor Replacement or Brake Rotor Refinishing .
NOTE: 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.