Brake Drum Refinishing

Tools Required

• J 41013  Rotor/Drum Flange Resurfacing Kit
• J 42450-A  Hub Cleaning Kit

1. The brake drums do not require refinishing as part of routine brake system service. Do not refinish brake drums in an attempt to correct the following conditions:
   • Brake system noise (squeal, growl, groan)
   • Uneven and/or premature brake lining wear
   • Superficial or cosmetic corrosion/rust of the brake drum surface
   • Scoring of the brake drum surface (less than the maximum allowable specification)
2. Brake drums should only be refinished if the following conditions exist:
   • Excessive corrosion/rust and/or pitting
   • Cracks and/or heat spots
   • Excessive blueing discoloration
   • Scoring of the brake drum surface (in excess of the maximum allowable specification)
   • Radial runout in excess of the maximum allowable specification
3. Inspect each of the brake drums and determine if the brake drums can be refinished and remain within the maximum allowable diameter after refinish specification:
   1. With the tire and wheel assemblies removed, measure the diameter of each of the brake drums. Refer to Brake Drum Diameter Measurement .
   2. Inspect each of the brake drums for excessive surface wear and/or radial runout. Refer to Brake Drum Surface and Wear Inspection .
4. If the brake drums can be refinished, proceed with the rotor refinishing procedure.
5. If necessary, use the J 41013  in order to thoroughly clean any corrosion/rust from the brake drum flange.
6. Mount the brake drum to the brake lathe according to the lathe manufacturer's instructions.
7. Ensure that any vibration dampening attachments are securely in place.
8. With the brake lathe running, slowly bring in the cutting tool until it just contacts the brake drum friction surface.
9. Observe the witness mark on the brake drum. If the witness mark extends approximately three-quarters or more of the way around the brake drum surface, the brake drum is properly mounted to the lathe.
10. If the witness mark does not extend three-quarters or more of the way around the brake drum, re-mount the brake drum to the lathe.
11. Following the brake lathe manufacturer's instructions, refinish the brake drum.
12. After each successive cut, inspect the brake drum diameter. Refer to Brake Drum Diameter Measurement .
13. If at any time the brake drum exceeds the maximum allowable diameter after refinish specification, the brake drum must be replaced.
14. After refinishing the brake drum, use the following procedure in order to obtain the desired non-directional finish:
    1. Follow the brake lathe manufacturer's recommended speed setting for applying a non-directional finish
    2. Using moderate pressure, apply the non-directional finish:
       • If the lathe is equipped with a non-directional finishing tool, apply the finish with 120 grit aluminum oxide sandpaper.
       • If the lathe is not equipped with a non-directional finishing tool, apply the finish with a sanding block and 150 grit aluminum oxide sandpaper.
    3. After applying a non-directional finish, clean each friction surface of the brake drum with denatured alcohol or an equivalent brake cleaner
15. Remove the brake drum from the brake lathe.
    IMPORTANT: Failure to clean the corrosion from the wheel bearing flange may result in increased lateral runout of the brake drum and brake system pulsation.
16. If necessary, use the J 42450-A  in order to thoroughly clean any corrosion from the wheel bearing flange.