Chevrolet Silverado / GMC Sierra. Service manual — part 1504

Fig. 1: Measuring Brake Rotor Thickness
Courtesy of GENERAL MOTORS CORP.

3. Using a micrometer calibrated in thousanths-of-a-millimeter, or ten-thousanths-of-an-inch,

measure and record the thickness of the brake rotor at four or more points, evenly spaced
around the rotor.

2008 Chevrolet Silverado 1500

2008 BRAKES Disc Brakes - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra & Silverado

Ensure 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 rotor, about 13 mm
(1/2 in) for each measurement.

4. Compare the lowest thickness measurement recorded to the following specifications:

Specification - Front Rotor JD9/JH6/JH7:

Brake rotor minimum allowable thickness after refinishing 37.0 mm (1.457 in)

Brake rotor discard thickness 36.50 mm (1.437 in)

Specification - Front Rotor JF3/JF7:

Brake rotor minimum allowable thickness after refinishing 28.0 mm (1.10 in)

Brake rotor discard thickness 28.0 mm (1.10 in)

Specification - Rear Rotor JD9:

Brake rotor minimum allowable thickness after refinishing 18.5 mm (0.728 in)

Brake rotor discard thickness 18.0 mm (0.709 in)

Specification - Rear Rotor JH6:

Brake rotor minimum allowable thickness after refinishing 28.0 mm (1.102 in)

Brake rotor discard thickness 27.50 mm (1.083 in)

Specification - Rear Rotor JH7:

Brake rotor minimum allowable thickness after refinishing 29.0 mm (1.142 in)

Brake rotor discard thickness 28.50 mm (1.122 in)

5. If the lowest thickness measurement of the brake rotor is above the minimum allowable

thickness after refinishing specification, the rotor may be able to be refinished, depending
upon surface and wear conditions which may be present.

6. If the lowest thickness measurement of the brake rotor is at or below the minimum

allowable thickness after refinishing specification, the rotor may not be refinished.

7. If the lowest thickness measurement of the brake rotor is at or below the discard thickness

specification, the rotor requires replacement.

BRAKE ROTOR THICKNESS VARIATION MEASUREMENT

CAUTION: Refer to Brake Dust Caution .

2008 Chevrolet Silverado 1500

2008 BRAKES Disc Brakes - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra & Silverado

1. If the inboard friction surface of the brake rotor is not accessible, reposition and support the

caliper with the brake pads. Refer to Front Disc Brake Pads Replacement (JH6, JH7) or
Front Disc Brake Pads Replacement (JD9, JF3, JF7) and/or Rear Disc Brake Pads
Replacement (JH6, JH7) or Rear Disc Brake Pads Replacement (JD9).

2. Clean the friction surfaces of the brake rotor with denatured alcohol, or an equivalent

approved brake cleaner.

IMPORTANT: 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.

2008 Chevrolet Silverado 1500

2008 BRAKES Disc Brakes - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra & Silverado

Fig. 2: Measuring Brake Rotor Thickness
Courtesy of GENERAL MOTORS CORP.

3. Using a micrometer calibrated in thousanths-of-a-millimeter, or ten-thousanths-of-an-inch,

measure and record the thickness of the brake rotor at four or more points, evenly spaced
around the rotor.

2008 Chevrolet Silverado 1500

2008 BRAKES Disc Brakes - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra & Silverado