Regal V6-3.8L VIN K (1997)
Brake Drum: Service and Repair
Refinishing Brake Drums
If a drum must be refinished, remove only enough metal to obtain a true, smooth braking surface. If a drum does not clean up when refinished to a
maximum rebore diameter, as shown in specifications, replace it. Removal of more metal will affect heat dissipation and may cause drum distortion.
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 which does not meet the specifications; instead, replace it.
When refinishing a brake drum, resurface the drum to a dimension no more than 0.76 mm (0.030 inch) less than the discard diameter. The refinish
diameter is the maximum diameter the drum may be refinished to and still allow safe braking action. If this dimension is exceeded, the brake drum will
wear beyond the discard diameter during normal brake wear.
Always use sharp cutting tools or bits. Dull or worn tools leave a poor surface finish which will affect initial braking performance. Always use vibration
dampening attachments when refinishing braking surfaces. These attachments eliminate tool chatter so that a better finish can be obtained.
The optimum speed for refinishing braking surfaces is a spindle speed of 200 rpm. Cross feed for rough cutting should range from 0.25 to 0.15 mm
(0.010 to 0.006 inch) per revolution. Finish cuts should be made at cross feed no greater than 0.05 mm (0.002 inch) per revolution.
After cutting on brake lathe, finish the surface with 80 to 120 grit emery cloth backed with a flat piece of steel or wood, while lathe is running. This will
break up any threading left from the cutting tool.
