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.

Warning: Refer to Brake Fluid Irritant Warning in the Preface section.

Caution: Refer to Brake Fluid Effects on Paint and Electrical Components Caution in the Preface section.

  1. Apply and fully release the parking brake 6 times.
  2. Verify that the parking brake pedal releases completely.
  3. • Turn ON the ignition. Verify that the BRAKE indicator lamp is off.
    • If the BRAKE indicator lamp is on, ensure that the parking brake pedal is in release mode and fully returned to stop. Remove the slack in the front parking brake cable by pulling downward on the cable.
  4. Raise and suitably support the vehicle. Refer to Lifting and Jacking the Vehicle.
  5. Remove the rear tire and wheel assemblies. Refer to Tire and Wheel Removal and Installation.

  6. Object Number: 177186  Size: SH
  7. Remove both rear caliper brackets. Refer to Rear Brake Caliper Bracket Replacement.
  8. Relieve tension on the park brake system at the park brake equalizer.
  9. Remove both rear brake rotors. Refer to Rear Brake Rotor Replacement.

  10. Object Number: 177200  Size: SH
  11. Set the J 21177-A inside of the park brake drum (1) at the widest point.
  12. • Place the contacts on the tool to the widest point of the drum.
    • Tighten the set screw on the tool to ensure the proper measurement when removing the tool from the drum.

    Object Number: 177201  Size: SH
  13. Position the J 21177-A over the park brake shoe (1) at the widest point.
  14. Turn the adjuster on the actuator until the park brake shoe just contacts the J 21177-A .
  15. Repeat steps 8-10 for the opposite side.
  16. Install both rear brake rotors. Refer to Rear Brake Rotor Replacement.
  17. Install both rear caliper brackets. Refer to Rear Brake Caliper Bracket Replacement.
  18. Install the rear tire and wheel assemblies. Refer to Tire and Wheel Removal and Installation.

  19. Object Number: 177170  Size: SH
  20. Adjust the parking brake by turning the nut at the equalizer (2) while spinning both rear wheels. When either rear wheel starts to drag, back off the nut one full turn.
  21. Lower the vehicle to curb height.
  22. Apply the parking brake, then inspect for rotation of the rear wheels. If the rear wheels rotate during this inspection, then readjust the parking brake shoes.
  23. Release the parking brake. Verify that the wheels rotate freely.
  24. Lower the vehicle.