Brake Rotor Thickness Measurement

Brake Rotor Thickness Measurement

Caution: Refer to Brake Dust Caution (Brake Dust Caution) in Cautions and Notices.
1. Raise and support the vehicle. Refer to Lifting and Jacking the Vehicle (Service and Repair) in General Information.
2. Remove the wheels. Refer to Tire and Wheel Removal and Installation (Service and Repair) in Tires and Wheels.
3. Clean the friction surfaces of the brake disc with denatured alcohol, or an equivalent approved brake cleaner.




4. Using a micrometer calibrated in thousandths-of-a-millimeter, or ten-thousandths-of-an-inch, measure and record the thickness of the brake disc at 4 points, evenly spaced around the brake disc.
5. Make sure that the measurements are only taken within the friction surfaces and that the micrometer is positioned the same distance from the outer edge of the brake disc, about 13 mm (1/2 in), for each measurement.
6. Compare the lowest thickness measurement recorded to the following specification:


Specification - Front (G8)
* Brake disc minimum allowable thickness after refinishing: 28.75 mm (1.13 in).
* Brake disc discard thickness: 28 mm (1.1 in)



Specification - Front (G8-GXP)
* Brake disc minimum allowable thickness after refinishing: 31 mm (1.22 in).
* Brake disc discard thickness: 30 mm (1.18 in)



Specification - Rear
* Brake disc minimum allowable thickness after refinishing: 20.75 mm (0.82 in)
* Brake disc discard thickness: 20 mm (0.80 in)

7. If the lowest thickness measurement of the brake disc is above the minimum allowable thickness after refinishing specification, the brake disc may be able to be refinished, depending upon surface and wear conditions which may be present.
8. If the lowest thickness measurement of the brake disc is at or below the minimum allowable thickness after refinishing specification, the brake disc may not be refinished.
9. If the lowest thickness measurement of the brake disc is at or below the discard thickness specification, the brake disc requires replacement.