Refinishing Procedure
WARNING: This page is about a different car, the 2009 GMC Sierra, 2009 GMC Cab & Chassis Sierra, 2009 Chevrolet Silverado, and 2009 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
- 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)
- 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
- 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:
- With the tire and wheel assemblies removed, measure the diameter of each of the brake drums. Refer to Brake Drum Diameter Measurement .
- Inspect each of the brake drums for excessive surface wear and/or radial runout. Refer to Brake Drum Surface and Wear Inspection .
- If the brake drums can be refinished, proceed with the rotor refinishing procedure.
- If necessary, use the J 41013 in order to thoroughly clean any corrosion/rust from the brake drum flange.
- Mount the brake drum to the brake lathe according to the lathe manufacturer's instructions.
- Ensure that any vibration dampening attachments are securely in place.
- With the brake lathe running, slowly bring in the cutting tool until it just contacts the brake drum friction surface.
- 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.
- 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.
- Following the brake lathe manufacturer's instructions, refinish the brake drum.
- After each successive cut, inspect the brake drum diameter. Refer to Brake Drum Diameter Measurement .
- If at any time the brake drum exceeds the maximum allowable diameter after refinish specification, the brake drum must be replaced.
- After refinishing the brake drum, use the following procedure in order to obtain the desired non-directional finish:
- Follow the brake lathe manufacturer's recommended speed setting for applying a non-directional finish
- 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.
- After applying a non-directional finish, clean the friction surface of the brake drum with denatured alcohol or an equivalent brake cleaner and wipe the friction surface using a clean shop towel to remove metal particles remaining from machining. Repeat the cleaning process if necessary to remove all metal particles.
- Remove the brake drum from the brake lathe.NOTE: Failure to clean the corrosion from the wheel bearing flange may result in increased lateral runout of the brake drum and brake system pulsation.
- If necessary, use the J 42450-A in order to thoroughly clean any corrosion from the wheel bearing flange.