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Disc Brake System Testing

WARNING: This page is about a different car, the 2003 Oldsmobile Aurora. However, it is still accessible from the selected car via links, so may be relevant.
NOTE: The numbers below refer to the step numbers on the diagnostic table:
  1. 9  - Lubricant leaks from non-brake system components may come in contact with and contaminate brake system components.
  2. 10  - Lubricant leaks from non-brake system components may come in contact with and contaminate brake system components.
  3. 12  - Disc brake rotor shields/backing plates that come in contact with disc brake rotors may cause brake system noise.
  4. 15  - Disc brake rotor thickness variation that exceeds the maximum acceptable level can cause brake pulsation.
  5. 19  - Disc brake rotor thickness variation that exceeds the maximum acceptable level can cause brake pulsation.
  6. 22  - Disc brake rotor assembled lateral runout (LRO) that exceeds the maximum acceptable level can lead to thickness variation.
  1. Were you sent here from a Brake Symptom Test or Table? If so, go to next step. If not, go to DIAGNOSTIC STARTING POINT - HYDRAULIC BRAKES  under TROUBLE SHOOTING.
  2. Visually inspect the disc brake pads for the following:
    • Lining thickness.
    • 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.
  6. 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 BRAKE PADS  under REMOVAL & INSTALLATION. After repairs are complete, go to step  12 .
    7. CAUTION: 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.
    NOTE: DO NOT disconnect the hydraulic brake flex hoses from the calipers.
  7. Remove the (front and/or rear) disc brake calipers (as appropriate) from the mounting brackets and support the calipers. Inspect the disc brake caliper mounting bracket and the mounting/sliding hardware for the following conditions:
    • Loose, bent, cracked, or damaged caliper mounting bracket.
    • Binding or seized hardware.
    • Worn, damaged or missing hardware components.
    Replace components as required.
    • Front And Rear Brake Caliper Bracket Replacement
    • Front And Rear Disc Brake Hardware Replacement
    See REMOVAL & INSTALLATION  for appropriate procedures. Replace the unevenly-worn, loose or damaged disc brake pads as a complete axle set. See BRAKE PADS  under REMOVAL & INSTALLATION. After repairs are complete, go to step  12 .
  8. Inspect the disc brake calipers, brake hoses and brake pipes for evidence of an external brake fluid leak. Replace any components found to be leaking brake fluid.
    • Brake Caliper Overhaul
    • Brake Caliper Replacement
    • Brake Hose Replacement
    • Brake Pipe Replacement
    See REMOVAL & INSTALLATION  or OVERHAUL  for appropriate procedures. 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 wheel drive shaft outer seals (boots) for damage and evidence of a grease leak. Replace any wheel drive shaft seal (boot) that is found to be leaking grease which may be the source of the contamination to the pads. 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. Inspect the automatic transmission cooling system lines, if equipped, for damage and evidence of an external fluid leak which may be the source of the contamination to the pads. Inspect the power steering system hoses for damage and evidence of an external fluid leak which may be the source of the contamination to the pads. Replace any components found to be leaking fluid which may be the source of the contamination to the pads. Did you find and correct the source of the leak causing contamination of the pads? If so, go to next step.
    11. CAUTION: 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.
  11. Clean the remaining disc brake system components to remove any traces of the contaminant. Remove the (front and/or rear) disc brake calipers (as appropriate) from the mounting brackets and support the calipers. See BRAKE CALIPERS  under REMOVAL & INSTALLATION. DO NOT disconnect the hydraulic brake flex hoses from the calipers. Inspect the disc brake caliper mounting/sliding hardware for the following conditions:
    • Binding.
    • Seized hardware.
    • Distorted, worn, damaged or missing hardware components.
    Replace the caliper mounting/sliding hardware components as required. See DISC BRAKE HARDWARE  under REMOVAL & INSTALLATION. Replace the contaminated disc brake pads as a complete axle set. See BRAKE PADS  under REMOVAL & INSTALLATION. After repairs are complete, go to next step.
  12. Visually inspect each of the rear disc brake rotor shields/backing plates for evidence of contact with the brake rotors. Are any of the rear brake rotor shields/backing plates contacting the brake rotors? If so, go to next step. If not, go to step  14 .
  13. Repair or replace the rear disc brake rotor shields/backing plates as required. After repairs are complete, go to next step.
  14. 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. Does the disc brake rotor meet the minimum requirements for refinishing? If so, go to next step. If not, go to step  18 .
  15. Inspect each of the disc brake rotors for thickness variation that exceeds the maximum acceptable level. See BRAKE ROTOR THICKNESS VARIATION MEASUREMENT  in DISC BRAKE SYSTEM under ADJUSTMENTS & INSPECTIONS. Does the brake rotor exhibit thickness variation that exceeds the maximum acceptable level? If so, go to step  17 . If not, go to next step.
  16. 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.
    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 conditions listed previously, it requires refinishing. Does the brake rotor require REFINISHING? If so, go to next step. If not, go to step  22 .
  17. Refinish the brake rotor. See BRAKE ROTOR REFINISHING  in DISC BRAKE SYSTEM under ADJUSTMENTS & INSPECTIONS. Inspect the brake rotor thickness. See BRAKE ROTOR THICKNESS MEASUREMENT  in DISC BRAKE SYSTEM under ADJUSTMENTS & INSPECTIONS. Were you able to refinish the brake rotor within the minimum requirements? If so, go to step  22 . If not, go to step  21 .
  18. Is the brake rotor at or below the discard requirements? If so, go to step  21 . If not, go to next step.
  19. Inspect each of the disc brake rotors for thickness variation that exceeds the maximum acceptable level. See BRAKE ROTOR THICKNESS VARIATION MEASUREMENT  in DISC BRAKE SYSTEM under ADJUSTMENTS & INSPECTIONS. Does the brake rotor exhibit thickness variation that exceeds the maximum acceptable level? If so, go to step  21 . If not, go to next step.
  20. 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.
    Make a determination for each brake rotor if the rotor requires replacement based upon the results of the inspection. If the brake rotor exhibits any of the conditions listed previously, it requires replacement. Does the brake rotor require replacement? If so, go to next step. If not, go to step  22 .
  21. Replace the brake rotor. See BRAKE ROTORS  under REMOVAL & INSTALLATION. Did you complete the replacement? If so, go to step  24 .
  22. Inspect each of the disc brake rotors for assembled lateral runout (LRO) that exceeds the maximum acceptable level. See BRAKE ROTOR ASSEMBLED LATERAL RUNOUT (LRO) MEASUREMENT  . Does the brake rotor exhibit assembled LRO that exceeds the maximum acceptable level? If so, go to next step. If not, go to step  24 .
  23. Correct the LRO for each brake rotor that was determined to have LRO exceeding the maximum acceptable level. See BRAKE ROTOR ASSEMBLED LATERAL RUNOUT (LRO) CORRECTION  . Did you complete the operation? If so, go to next step.
  24. Install or connect components that were removed or disconnected during diagnosis. Did you complete the operation? If so, then system is okay. If system is not okay, go to step  2 .
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