Brake Drum: Service and Repair

REFINISHING BRAKE DRUMS
When performing routine brake maintenance, drums should not be refinished unless there is a brake pulsation caused by the drums or the drums are excessively scored.

If a drum is to be refinished, only enough metal should be removed to obtain a true, smooth braking surface. If a drum does not clean-up when refinished to a maximum rebore diameter as shown in the specifications at the end of this section, it must be replaced. Removal of more metal will affect dissipation of heat and may cause distortion of the drum.

All brake drums have a maximum diameter cast into them. This diameter is the maximum wear diameter and not a refinish diameter. Do not refinish a brake drum that will not meet specifications. Any drum which exceeds the maximum refinish diameter after refinishing should be replaced.