C 2500 Truck 2WD V8-5.7L VIN R (1997)
Brake Rotor/Disc: Testing and Inspection
Brake Rotor Diagnosis and Service Guidelines
This article has been updated with bulletin No: 00-05-22-002B.
BRAKE ROTOR DIAGNOSIS AND SERVICE GUIDELINES
IMPORTANT: Certain conditions may apply to individual vehicles regarding specific repairs which differ from those outlined in this bulletin. For
information regarding lateral runout correction, refer to Bulletin Number 01-05-23-001A, Brake Align System for Brake Rotor Lateral Runout
Correction. For other conditions, refer to those specific repairs in applicable bulletins.
Original equipment rotor surfaces are ground to ensure smooth finish and parallelism between mounting and friction surfaces. New rotors SHOULD
NOT be resurfaced before installation. When rotor turning is necessary, it is essential that you use a high quality brake lathe. Rotors, when remounted on
the hub, should have less than .055 mm (.002 in) lateral runout.
Brake rotors should only be turned when one of the following rotor surface conditions exist:
1. Severe scoring - depth in excess of 1.5 mm (0.060 in).
2. Pulsation concerns from:
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Lateral runout in excess of .055 mm (.002 in).
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Thickness variation in excess of 0.025 mm (0.001 in).
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Excessive corrosion on rotor braking surfaces.
Rotors are not to be resurfaced in an attempt to correct the following conditions:
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Noise/squeal
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Cosmetic corrosion
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Routine pad replacement
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Discoloration/hard spots
Explanation of Brake Rotor Warranty Service Procedure
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Rotor refacing during normal pad replacement is not necessary.
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Rotor refacing for cosmetic corrosion is unnecessary. Clean up of braking surfaces can be accomplished by 10-15 moderate stops from 62-75
km/h (35-40 mph) with cooling time between stops.
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Rotor service is ineffective in correcting brake squeal and/or premature lining wear out and should not be used to address these conditions
unless specifically directed by a service bulletin.
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When installing new rotors, DO NOT reface them. If a new rotor has more than .055 mm (.002 in) lateral runout when properly mounted on
the hub, it may be machined using an approved on-car lathe or follow correction plate procedure found in Corporate Bulletin Number
01-05-23-001A.
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Ensure bearing flanges and rotor mounting surfaces are free of corrosion when installing rotors to prevent inducing lateral runout. Use Kent
Moore tool J 42450A to clean the corrosion around the wheel studs.
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Always mark the position of the rotor on the hub before removal and reinstall the rotor in the same position. Rotors with perceived hard spots
or discoloration should not be serviced. These conditions are normal. Installation of new rotors does not require pad replacement. Do not
replace pads unless their condition requires it. It is not necessary to replace rotors in pairs. Rotors may be replaced individually. However,
caution should be exercised, as a variance in surface finish may cause a brake pull condition.
A torque limiting socket or torque wrench must be used to insure that the wheel nuts are tightened to specification. This should be done in 3 steps using
the star pattern:
1. Hand tighten all 5 lug nuts using the star pattern.
2. Tighten all 5 nuts to approximately 1/2 spec. using the star pattern.
3. Tighten all 5 nuts to full spec. using the star pattern.
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Never use lubricants or penetrating fluids on wheel studs, nuts or mounting surfaces. Wheel nuts, studs and mounting surfaces must be clean
and dry.
BRAKE SERVICE TECHNIQUES
1. Clean and lubricate all metal-to-metal contact points (i.e. caliper to knuckle, pad to knuckle, etc).
2. Clean and lubricate slide pins, if applicable.
3. Set correct clearances (i.e. caliper to knuckle, etc.), if applicable.
4. Clean rotor and hub mounting surfaces. Use Kent Moore tool J 42450 to clean around the wheel studs.
5. Verify lateral runout of the rotor with a dial indicator (rotor held on hub with 3 or more wheel nuts and washers).
PULSATION
IMPORTANT: Brake pulsation is often caused by factors outside customer control. Brake pulsation concerns may result from two basic conditions:
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Pulsation is caused by brake rotor thickness variation. Thickness variation causes the piston in the brake caliper to "pump" in and out of the
