GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 1999 🢒 GMC C-Series Medium Duty Truck B7 🢒 Brakes 🢒 Air Drums 🢒 Brake Drum Replacement

Removal Procedure

Caution: Avoid taking the following actions when you service wheel brake parts:

   • Do not grind brake linings.
   • Do not sand brake linings.
   • Do not clean wheel brake parts with a dry brush or with compressed air.
Some models or aftermarket brake parts may contain asbestos fibers which can become airborne in dust. Breathing dust with asbestos fibers may cause serious bodily harm. Use a water-dampened cloth in order to remove any dust on brake parts. Equipment is available commercially in order to perform this washing function. These wet methods prevent fibers from becoming airborne.

Notice: A new brake drum must have the protective coating removed from the friction surface before being placed in service. Use denatured alcohol or an equivalent approved brake cleaner, and wipe the surface clean with clean cloths. Do not use gasoline, kerosene or other oil base solvents that can leave an oily residue. This residue is damaging to brake linings and is flammable.

  1. Raise and support the vehicle. Refer to Lifting and Jacking the Vehicle in General Information.
  2. Remove the tires and the wheel assembly. Refer to appropriate type of tire from the following list: in Tires and Wheel.
    3. • Wheel Removal (Disc Type - Single Front/Rear)
    • Wheel Removal (Disc Type - Dual/Rear)
    • Wheel Removal (Cast Type - Single Front/Rear)
    • Wheel Removal (Cast Type - Dual/Rear)

    Object Number: 201765 Size: SH
  3. Cage the rear air brake chamber. Refer to Caging the Rear Air Brake Chamber .
  4. Release the air brake automatic slack adjuster fully in order to retract the shoes then the air drum will clear the brake linings.
    5. 4.1. Disengage the pawl with a screwdriver.
    4.2. Turn the air brake automatic slack adjuster adjusting nut until the brakes shoes are fully retracted.
    4.3. Release the pawl in order to snap the pawl into engagement after the brake shoes have retracted.

    Object Number: 201685 Size: SH
  5. Slide the air drum from the hub (outboard mounted). For the inboard mounted air drums.
  6. Clean the air drum using the Brakes Parts Cleaner GM P/N 12345754 or equivalent.
  7. Inspect the air drum. Refer to Brake Drum Inspection .

Installation Procedure

    Object Number: 201685 Size: SH
  1. Slide the Air Drum onto the hub (outboard mounted). For the inboard mounted Air Drums.
  2. Adjust the wheel bearings if needed. Refer to Wheel Bearing Adjustment .
  3. Install the tire and the wheel assembly. Refer to the following prcedures: in Tires and Wheel.
    4. • Wheel Installation (Disc Type - Single Front/Rear)
    • Wheel Installation (Disc Type - Dual/Rear)
    • Wheel Installation (Cast Type - Single Front/Rear)
    • Wheel Installation (Cast Type - Dual/Rear)
  4. Adjust the brakes. Refer to Air Drum Brake Adjustment .
  5. Remove the supports.
  6. Lower the vehicle. Refer to Lifting and Jacking the Vehicle in General Information.
  7. Check the brakes for the proper operation.