GM Service Manual Online
For 1990-2009 cars only

Special Tools

J-21177-A Drum to Brake Shoe Clearance Gage

Warning: Refer to Brake Dust Warning in the Preface section.

Note: The park brake cable nut is a nylon lock type. Use ONLY HAND TOOLS when loosening or tightening the adjusting nut.


    Object Number: 1744444  Size: SH
  1. Remove the console rear trim plate. Refer to Console Rear Trim Plate Replacement.
  2. Ensure that the park brake lever is in the fully released position.
  3. With the park brake lever in the released position, loosen the adjusting nut (1) enough to completely relieve tension on the front cable.

  4. Object Number: 891757  Size: SH
  5. Raise and support the vehicle. Refer to Lifting and Jacking the Vehicle.
  6. Remove the rear tire and wheel assemblies. Refer to Tire and Wheel Removal and Installation.
  7. Remove the brake drums. Refer to Brake Drum Replacement.
  8. Position the J-21177-A Drum to Brake Shoe Clearance Gage to widest point of the brake drum inside diameter.
  9. Firmly hand tighten the set screw on the J-21177-A Drum to Brake Shoe Clearance Gage .

  10. Object Number: 891758  Size: SH
  11. Remove the J-21177-A Drum to Brake Shoe Clearance Gage from the brake drum and position it over the corresponding brake shoe assembly at its widest point.
  12. While holding the J-21177-A Drum to Brake Shoe Clearance Gage in position, insert a 0.375 mm (0.015 in) feeler gage between one side of the J-21177-A Drum to Brake Shoe Clearance Gage , and the corresponding brake shoe lining.
  13. Rotate the brake shoe adjuster screw until the brake shoe linings contact the J-21177-A Drum to Brake Shoe Clearance Gage , and the feeler gage.
  14. Specification
    Brake shoe lining-to-drum clearance: 0.375 mm (0.015 in).

  15. Repeat the above steps for the opposite brake drum and brake shoe assembly.
  16. Install the brake drums. Refer to Brake Drum Replacement.
  17. Adjust the park brake. Refer to Parking Brake Adjustment.
  18. Install the rear tire and wheel assemblies. Refer to Tire and Wheel Removal and Installation.
  19. Lower the vehicle.
  20. Install the console rear trim plate. Refer to Console Rear Trim Plate Replacement.
  21. Release the park brake lever.