Cobalt L4-2.4L VIN B (2006)
Caution: Refer to Brake Dust Caution in Service Precautions.
1. If the inboard friction surface of the brake rotor is not accessible, reposition and support the caliper with the brake pads.
2. Clean the friction surfaces of the brake rotor with denatured alcohol, or an equivalent approved brake cleaner.
3. Inspect the friction surfaces of the brake rotor for the following braking surface conditions:
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Heavy rust and/or pitting. Light surface rust can be removed with an abrasive disc. Heavy surface rust and/or pitting must be removed by
refinishing the rotor.
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Cracks and/or heat spots
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Excessive blueing discoloration
4. If the friction surfaces of the brake rotor exhibit one or more of the braking surface conditions listed, the rotor requires refinishing or replacement.
5. Using a micrometer calibrated in thousandths-of-a-millimeter, or ten-thousandths-of-an-inch, measure and record the scoring depth of any grooves
present on the rotor friction surfaces.
6. Compare the groove scoring depth recorded to the following specification:
Brake rotor maximum allowable scoring: 1.50 mm (0.059 inch)
7. If the brake rotor scoring depth exceeds the specification, or if an excessive amount of scoring is present, the rotor requires refinishing or
replacement.
Brake Rotor Thickness Measurement
Brake Rotor Thickness Measurement
Caution: Refer to Brake Dust Caution in Service Precautions.
1. If the inboard friction surface of the brake rotor is not accessible, reposition and support the caliper with the brake pads.
2. Clean the friction surfaces of the brake rotor with denatured alcohol, or an equivalent approved brake cleaner.
3. Using a micrometer calibrated in thousandths-of-a-millimeter, or ten-thousandths-of-an-inch, measure and record the thickness of the brake rotor at
4 or more points, evenly spaced around the rotor.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 inch), for each measurement.
4. Compare the lowest thickness measurement recorded to the following specifications:
Specification - Front J41/JM4
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Brake rotor minimum allowable thickness after refinishing: 22.75 mm (0.896 inch)
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Brake rotor discard thickness: 22.0 mm (0.87 inch)
Specification - Front JL9
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Brake rotor minimum allowable thickness after refinishing: 23.0 mm (0.906 inch)
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Brake rotor discard thickness: 22.8 mm (0.898 inch)
Specification - Rear
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Brake rotor minimum allowable thickness after refinishing: 12.0 mm (0.472 inch)