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Disc Brake System Diagnosis

WARNING: This page is about a different car, the 2003 Chevrolet Corvette. However, it is still accessible from the selected car via links, so may be relevant.
  1. Were you sent here from a symptom test? If so, go to next step. If not, go to HYDRAULIC BRAKE SYSTEM DIAGNOSTIC STARTING POINT  under TROUBLE SHOOTING.
  2. Visually inspect the disc brake pads for the following conditions:
    • Lining thickness below specifications.
    • Uneven and/or abnormal wear, edge-to-edge and/or side-to-side.
    • Evidence of contamination from an external substance.
    • Looseness or damage, including pad hardware.
    Did you find any conditions to indicate a concern with any of the front and/or rear disc brake pads? If so, go to next step. If not, go to step  12.
  3. Are any of the front and/or rear disc brake pads contaminated? If so, go to step  8. If not, go to next step.
  4. Are any of the front and/or rear disc brake pads worn unevenly? If so, go to step  7. If not, go to next step.
  5. Are any of the front and/or rear disc brake pads and/or pad hardware loose or damaged? If so, go to step  7. If not, go to next step.
    • Remove and inspect the worn disc brake pads for glazing, looseness, heat spots or damage.
    • Replace the worn disc brake pads as a complete axle set. See FRONT BRAKE PADS  or REAR BRAKE PADS  under REMOVAL & INSTALLATION.

    After completing the inspection and/or replacement, go to step  12.

    7. NOTE: Support the brake caliper with heavy mechanic's wire, or equivalent, whenever it is separated from its mount and the hydraulic flexible brake hose is still connected. Failure to support the caliper in this manner will cause the flexible brake hose to bear the weight of the caliper, which may cause damage to the brake hose and in turn may cause a brake fluid leak.
    1. Remove the front and/or rear disc brake calipers, as appropriate, from the mounting brackets and support the calipers. Do NOT disconnect the hydraulic brake flex hoses from the calipers. See FRONT BRAKE CALIPER  or REAR BRAKE CALIPER  under REMOVAL & INSTALLATION.
    2. Inspect the disc brake caliper mounting bracket and the mounting/sliding hardware for a loose, bent, cracked or damaged caliper mounting bracket, binding or seized hardware, or worn, damaged or missing hardware components. See DISC BRAKE HARDWARE  under REMOVAL & INSTALLATION.
    3. Replace components as required.
    4. Replace the unevenly-worn, loose or damaged disc brake pads as a complete axle set. See FRONT BRAKE PADS  or REAR BRAKE PADS  under REMOVAL & INSTALLATION.

    After completing the inspection and/or replacement, go to step  12.

  8. Inspect the disc brake calipers, brake hoses and brake pipes for evidence of an external brake fluid leak. Replace component(s) as necessary. See appropriate procedure in REMOVAL & INSTALLATION. Did you find and correct the source of the leak causing contamination of the pads? If so, go to step  11. If not, go to next step.
  9. Inspect the axle shaft outer seals for damage and evidence of a grease leak. Replace any axle shaft seal that is found to be leaking grease which may be the source of the contamination to the pads. See appropriate AXLE SHAFTS article in DRIVE AXLES. Did you find and correct the source of the leak causing contamination of the pads? If so, go to step  11. If not, go to next step.
  10. Repair/replace any components found to be leaking fluid which may be the source of the contamination to the pads. After repairs are complete, go to next step.
    11. NOTE: Support the brake caliper with heavy mechanic's wire, or equivalent, whenever it is separated from its mount and the hydraulic flexible brake hose is still connected. Failure to support the caliper in this manner will cause the flexible brake hose to bear the weight of the caliper, which may cause damage to the brake hose and in turn may cause a brake fluid leak.
    1. Clean the remaining disc brake system components to remove any traces of the contaminants.
    2. Remove the front and/or rear disc brake calipers, as appropriate, from the mounting brackets and support the calipers. Do NOT disconnect the hydraulic brake flex hoses from the calipers. See FRONT BRAKE CALIPER  or REAR BRAKE CALIPER  under REMOVAL & INSTALLATION.
    3. Inspect the disc brake caliper mounting/sliding hardware for binding or seized hardware, or distorted, worn, damaged or missing hardware components. See DISC BRAKE MOUNTING & HARDWARE INSPECTION  under ADJUSTMENTS & INSPECTIONS.
    4. Replace the caliper mounting/sliding hardware components as required. See DISC BRAKE HARDWARE  under REMOVAL & INSTALLATION.
    5. Replace the contaminated disc brake pads as a complete axle set. See FRONT BRAKE PADS  or REAR BRAKE PADS  under REMOVAL & INSTALLATION. After repairs are complete, go to next step.
  12. Check the thickness of each of the disc brake rotors. Make a determination for each brake rotor if the rotor can be refinished and remain above the minimum requirements. See DISC BRAKE SPECIFICATIONS . If the rotor can be refinished and remain above the minimum requirements, go to next step. If the rotor cannot be refinished and remain above the minimum requirements, go to step  15.
    1. Inspect each of the disc brake rotors for the following surface and wear conditions:
      • Heavy rust and/or pitting.
      • Cracks and/or heat spots.
      • Excessive blueing discoloration.
      • Deep or excessive scoring beyond maximum acceptable level.
      • Lateral runout beyond maximum acceptable level.
      • Thickness variation beyond maximum acceptable level.
    2. Make a determination for each brake rotor if the rotor requires refinishing based upon the results of the inspection. If the brake rotor exhibits any of the listed conditions, it requires refinishing. If the brake rotor requires refinishing, go to next step. If the brake rotor does not require refinishing, go to step  18.
  14. Refinish the brake rotor. Inspect the brake rotor thickness. See DISC BRAKE SPECIFICATIONS . Were you able to refinish the brake rotor within the minimum requirements? If so, go to step  18. If not, go to step  17.
  15. Is the brake rotor at or below the discard requirements? If so, go to step  17. If not, go to next step.
    1. Inspect each of the disc brake rotors for the following surface and wear conditions:
      • Heavy rust and/or pitting.
      • Cracks and/or heat spots.
      • Excessive blueing discoloration.
      • Deep or excessive scoring beyond maximum acceptable level.
      • Lateral runout beyond maximum acceptable level.
      • Thickness variation beyond maximum acceptable level.
    2. Make a determination for each brake rotor if the rotor requires replacing based upon the results of the inspection. If the brake rotor exhibits any of the listed conditions, it requires refinishing. If the brake rotor requires replacing, go to next step. If the brake rotor does not require replacing, go to step  18.
  17. Replace the brake rotor. See FRONT BRAKE ROTOR  or REAR BRAKE ROTOR  under REMOVAL & INSTALLATION. After repairs are complete, go to next step.
  18. Install or connect components that were removed or disconnected during diagnosis.
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