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Disc Brake System Testing

WARNING: This page is about a different car, the 2002 GMC Savana Special, 2002 GMC Savana Camper Special, 2002 GMC Savana, and 2002 Chevrolet Chevy Express. However, it is still accessible from the selected car via links, so may be relevant.
  1. Were you sent here from DIAGNOSTIC STARTING POINT - HYDRAULIC BRAKES? If so, go to next step. If not, see DIAGNOSTIC STARTING POINT - HYDRAULIC BRAKES  .
  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 disc brake pads? If so, go to next step. If not, go to step  11 .
  3. Are any of the disc brake pads contaminated? If so, go to step  8 . If not, go to next step.
  4. Are any of the disc brake pads worn unevenly? If so, go to step  7 . If not then go to next step.
  5. Are any of the disc brake pads and/or pad hardware loose or damaged? If so, go to step  7 . If not then 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  . After repairs got o to step . 11 .
    7. NOTE: Support the brake caliper with heavy mechanic's wire, or equivalent, whenever it is separated from it's 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.
  7. Remove the disc brake calipers (as appropriate) from the steering knuckles and support the calipers. Do NOT disconnect the hydraulic brake flex hoses from the calipers. See BRAKE CALIPER  . Inspect the disc brake caliper steering knuckle and the mounting/sliding hardware for the following conditions:
    • Loose, bent, cracked, or damaged steering knuckle.
    • Binding or seized hardware.
    • Worn, damaged or missing hardware components.
    Replace components as required. Refer to the following procedures as required: Replace the unevenly-worn, loose or damaged disc brake pads as a complete axle set. See BRAKE PADS  . After repairs are complete, go to step  11 .
  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. Refer to the following procedures as required: Did you find and correct the source of the leak causing contamination of the pads? If so, go to step  10 . If not, go to next step.
  9. Inspect the following systems for damage and evidence of an external fluid leak. Replace any components found to be leaking fluid which may be the source of the contamination to the pads. Refer to the following procedures:
    • See Trouble Shooting in Power Steering.
    • See Trouble Shooting in Engine Mechanical.
    • See Trouble Shooting in Automatic Transmission.
    When you find and correct the source of the leak causing contamination of the pads, go to next step.
    10. NOTE: Support the brake caliper with heavy mechanic's wire, or equivalent, whenever it is separated from it's 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.
  10. Clean the remaining disc brake system components to remove any traces of the contaminant. Remove the disc brake calipers (as appropriate) from the steering knuckles and support the calipers. DO NOT disconnect the hydraulic brake flex hoses from the calipers. See BRAKE CALIPER  . Inspect the disc brake caliper mounting/sliding hardware for the following conditions:
    • Binding or seized hardware.
    • Distorted, worn, damaged or missing hardware components.
    Replace the caliper mounting/sliding hardware components as required. See DISC BRAKE HARDWARE  . Replace the contaminated disc brake pads as a complete axle set. See BRAKE PADS  . After repairs are complete, go to next step.
  11. Visually inspect each of the disc brake rotor shields/backing plates for evidence of contact with the brake rotors. Are any of the brake rotor shields/backing plates contacting the brake rotors? If so, go to next step. If not, go step  13 .
  12. Repair or replace the disc brake rotor shields/backing plates as required. See DISC BRAKE SPLASH SHIELD  . After repairs are complete, go to next step.
  13. 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 BRAKE ROTOR THICKNESS MEASUREMENT  . Does the disc brake rotor meet the minimum requirements for REFINISHING? If so, go to next step. If not, go to step  16 .
  14. Inspect each of the disc brake rotors for the following surface and wear conditions:

    Braking Surface Conditions

    • Heavy rust and/or pitting.
    • Cracks and/or heat spots.
    • Excessive blueing discoloration.

    Braking Surface Wear Conditions

    • Deep or excessive scoring beyond maximum acceptable level.
    • Lateral runout beyond maximum acceptable level.
    • Thickness variation 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 following conditions, it requires refinishing.
    • Rotor exhibits one or more of the Braking Surface Conditions listed previously.
    • Rotor is beyond the acceptable level in one or more of the Braking Surface Wear Conditions listed previously.
    Does the brake rotor require REFINISHING? If so, go to next step. If not, go to step  19 .
  15. Refinish the brake rotor. See BRAKE ROTOR REFINISHING  . Inspect the brake rotor thickness. See BRAKE ROTOR THICKNESS MEASUREMENT  . Were you able to REFINISH the brake rotor within the minimum requirements? If so, go to step  19 . If not, go to step  18 .
  16. Is the brake rotor at or below the DISCARD requirements? If so, go to step  18 . If not, go to next step.
  17. Inspect each of the disc brake rotors for the following surface and wear conditions:

    Braking Surface Conditions

    • Heavy rust and/or pitting.
    • Cracks and/or heat spots.
    • Excessive blueing discoloration.

    Braking Surface Wear Conditions

    • Deep or excessive scoring beyond maximum acceptable level.
    • Lateral runout beyond maximum acceptable level.
    • Thickness variation beyond maximum acceptable level.
    Make a determination for each brake rotor if the rotor requires replacement based upon the results of the inspection. If a brake rotor exhibits any of the following conditions, it requires replacement.
    • Rotor exhibits one or more of the Braking Surface Conditions listed previously.
    • Rotor is beyond the acceptable level in one or more of the Braking Surface Wear Conditions listed previously.
    Does the brake rotor require replacement? If so, go to next step. If not, go to step  19 .
  18. Replace the brake rotor. See BRAKE ROTOR  . After repairs are complete, go to next step.
  19. Install or connect components that were removed or disconnected during diagnosis. Is condition still present? If so go to step  2 . If not, system is okay.
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