Disc Brake System Testing
- Were you sent here from a Brake Symptom table? If so, go to next step. If not, see DIAGNOSTIC STARTING POINT - HYDRAULIC BRAKE
under TROUBLE SHOOTING.
- 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.
See BRAKE PAD INSPECTION
in DISC BRAKES under TROUBLE SHOOTING. 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, the go to step 12
.
- Are any of the front and/or rear disc brake pads contaminated? If so, go to step 8
. If not, go to next step.
- 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.
- 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. When finished, go to step 12
.
- 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. 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.
See DISC BRAKE MOUNTING HARDWARE INSPECTION
in DISC BRAKE SYSTEM under TROUBLE SHOOTING. Replace components as required. 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. When finished, go to step 12
.
- 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. 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.
- Inspect the wheel drive shaft outer seals for damage and evidence of a grease leak. Replace any wheel drive 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 TRANSMISSIONS. 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.
- 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.
- Power Steering
- Engine Mechanical
- Automatic Transmission
See appropriate article as necessary. Correct the source of the leak causing contamination of the pads. When finished, go to next step.
- 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. Do Not disconnect the hydraulic brake flex hoses from the calipers. See FRONT BRAKE CALIPER
or REAR BRAKE CALIPER
under REMOVAL & INSTALLATION. Inspect the disc brake caliper mounting/sliding hardware for the following conditions:
- Binding or seized hardware.
- Distorted, worn, damaged or missing hardware components.
See DISC BRAKE MOUNTING HARDWARE INSPECTION
in DISC BRAKE SYSTEM under TROUBLE SHOOTING. 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 FRONT BRAKE PADS
or REAR BRAKE PADS
under REMOVAL & INSTALLATION. When finished, go to next step.
- 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
.
- Repair or replace the rear disc brake rotor shields/backing plates as required. See appropriate REAR SUSPENSION article in SUSPENSIONS. When finished, go to next step.
- 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
. See BRAKE ROTOR THICKNESS MEASUREMENT
under ADJUSTMENTS & INSPECTIONS. Does the disc brake rotor meet the minimum requirements for refinishing? If so, go to next step. If not, go to step 17
.
- 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.
See BRAKE ROTOR SURFACE AND WEAR INSPECTION
in DISC BRAKE SYSTEM under TROUBLE SHOOTING. 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 20
.
- Refinish the brake rotor. See REFINISHING BRAKE ROTOR
under ADJUSTMENTS & INSPECTIONS. Inspect the brake rotor thickness. See BRAKE ROTOR THICKNESS MEASUREMENT
in DISC BRAKE SYSTEM under TROUBLE SHOOTING. Were you able to refinish the brake rotor within the minimum requirements? If so, go to step 20
. If not, go to step 19
.
- Is the brake rotor at or below the discard requirements? If so, go to step 19
. If not, go to next step.
- 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.
See BRAKE ROTOR SURFACE AND WEAR INSPECTION
in DISC BRAKE SYSTEM under TROUBLE SHOOTING. 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 replacement? If so, go to next step. If not, go to step 20
.
- Replace the brake rotor. See FRONT BRAKE ROTOR
or REAR BRAKE ROTOR
under REMOVAL & INSTALLATION.
- Install or connect components that were removed or disconnected during diagnosis. When finished, repair is complete. Return to referencing procedure.