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Drum Brake System

WARNING: This page is about a different car, the 2003 GMC Sonoma, 2003 GMC Jimmy, 2003 Chevrolet S10 Pickup, and 2003 Chevrolet Blazer. However, it is still accessible from the selected car via links, so may be relevant.
  1. Were you sent here from SYMPTOMS - HYDRAULIC BRAKES  under TROUBLE SHOOTING? If so, go to the next step. If not, go to STARTING POINT - HYDRAULIC BRAKES .
  2. Remove the brake drums. See BRAKE DRUM  under REMOVAL & INSTALLATION. Inspect the drum brake shoes for the following conditions: Lining thickness below specifications. Uneven and/or abnormal wear, edge-to-edge and/or side-to-side. Contamination from an external substance. Looseness, damage, glazing, or incorrect lining material. Did you find any conditions to indicate a concern with any of the drum brake shoes? If so, go to the next step. If not, go to step  7.
  3. Are any of the brake shoes contaminated? If so, go to the next step. If not, go to step  5.
  4. Inspect the wheel cylinders for evidence of an external brake fluid leak. Replace any wheel cylinder that is found to be leaking brake fluid. See WHEEL CYLINDER  under REMOVAL & INSTALLATION. Did you complete the inspection and replacement? If so, go to step  6.
  5. Inspect the drum brake hardware for any components which are worn, damaged, discolored due to stress, broken or missing. See DRUM BRAKE ADJUSTING HARDWARE INSPECTION  under ADJUSTMENTS & INSPECTION. Replace components as required. See DRUM BRAKE HARDWARE  under REMOVAL & INSTALLATION. Replace the drum brake shoes. See DRUM BRAKE SHOE  under REMOVAL & INSTALLATION. Did you complete the inspection and replacement? If so, go to step  8.
  6. Clean the remaining drum brake system components to remove any traces of the contaminant. Inspect the drum brake hardware for any components which are worn, damaged, discolored due to stress, broken or missing. See DRUM BRAKE ADJUSTING HARDWARE INSPECTION  under ADJUSTMENTS & INSPECTION. Replace the drum brake hardware components as required. See DRUM BRAKE HARDWARE  under REMOVAL & INSTALLATION. Replace the contaminated brake shoes. See DRUM BRAKE SHOE  under REMOVAL & INSTALLATION. Did you complete the cleaning inspection and repair? If so, go to step  8.
  7. Inspect the drum brake hardware for any components which are worn, damaged, discolored due to stress, broken or missing. See DRUM BRAKE ADJUSTING HARDWARE INSPECTION  under ADJUSTMENTS & INSPECTION. Replace components as required. See DRUM BRAKE HARDWARE  under REMOVAL & INSTALLATION. Did you complete the inspection and, if necessary, the replacement? If so, go to the next step.
  8. Check the diameter of each of the brake drums. Make a determination for each brake drum if the drum can be refinished and remain above the minimum requirements. See DRUM DIAMETER MEASUREMENT  under ADJUSTMENTS & INSPECTION. Does the brake drum meet the minimum requirements for refinishing? If so, go to the next step. If not, go to step  11.
  9. Inspect each of the brake drums for surface and wear conditions: See DRUM SURFACE AND WEAR INSPECTION  under ADJUSTMENTS & INSPECTION. Make a determination for each brake drum if the drum requires refinishing based upon the results of the inspection. If the brake drum exhibits any of the conditions, it requires refinishing. Does the brake drum require refinishing? If so, go to the next step. If not, go to step  14.
  10. Refinish the brake drum. Inspect the brake drum diameter. See DRUM DIAMETER MEASUREMENT  under ADJUSTMENTS & INSPECTION. Were you able to refinish the brake drum within the minimum requirements? If so, go to step  14. If not, go to step  13.
  11. Is the brake drum at or below the discard requirements? If so, go to step  13. If not, go to the next step.
  12. Inspect each of the brake drums for the surface and wear conditions: See BRAKE DRUM SURFACE & WEAR INSPECTION  under ADJUSTMENTS & INSPECTION. Make a determination for each brake drum if the drum requires replacement based upon the results of the inspection. If a brake drum exhibits any of the conditions, it requires replacement. Does the brake drum require replacement? If so, go to the next step. If not, go to step  14.
  13. Replace the brake drum. See BRAKE DRUM  under REMOVAL & INSTALLATION. After repairs are complete, go to the next step.
  14. Inspect the brake shoes for proper adjustment. See DRUM BRAKE ADJUSTMENT  under ADJUSTMENTS & INSPECTION. Are the brake shoes adjusted properly? If so, go to step  18. If not, go to the next step.
  15. Inspect the components of the brake drum adjustment hardware system for free movement and correct operation. See DRUM ADJUSTING HARDWARE INSPECTION  under ADJUSTMENTS & INSPECTION. Do the drum brake adjusting hardware components operate freely and correctly? If so, go to step  17. If not, go to the next step.
  16. Replace the drum brake adjusting hardware components as necessary. See DRUM BRAKE ADJUSTING HARDWARE  under REMOVAL & INSTALLATION. After repairs are complete, go to the next step.
  17. Adjust the drum brake shoes. See DRUM BRAKE ADJUSTMENT  under ADJUSTMENTS & INSPECTION. Were you able to complete the adjustment? If so, go to step  20. If not, return to SYMPTOMS - HYDRAULIC BRAKES  under TROUBLE SHOOTING.
  18. Inspect the drum brake backing plate for the following:
    • Excessive wear or rust.
    • Damage and/or evidence of contact with the brake drum.

    Does the drum brake backing plate exhibit any of these conditions? If so, go to the next step. If not, go to step  20.

  19. Repair or replace the drum brake backing plate as necessary. See DRUM BRAKE BACKING PLATE  under REMOVAL & INSTALLATION. Go to the next step.
  20. Install or connect components that were removed or disconnected during diagnosis. Did you complete the operation? If so, the drum brake system is okay, Return to SYMPTOMS - HYDRAULIC BRAKES  under TROUBLE SHOOTING.
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