Refinishing Brake Drums

When performing routine brake maintenance, drums should not be refinished unless there is a brake pulsation caused by the drums or 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, it must be replaced. Removal of more metal will affect dissipation of heat and may cause distortion of drum.
All 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 maximum refinish diameter after refinishing should be replaced.

IMPORTANT: When refinishing drums, always use sharp cutting inserts (tips, bits). dull or worn tools leave a poor surface finish which will affect initial braking performance. Vibration dampening attachments should always be used when refinishing braking surfaces. These attachments eliminate tool chatter and will result in better surface finish.

FOLLOW ALL BRAKE LATHE'S MACHINING INSTRUCTIONS TO OBTAIN BEST POSSIBLE SURFACE FINISH QUALITY.