Cutlass Supreme V6-191 3.1L VIN M SFI (1997)
Brake Drum: Service and Repair
Brake Drum Refinishing
WHEN TO REPLACE A DRUM
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, replace it. Removal of more metal will affect heat dissipation and may cause drum distortion.
MAXIMUM DIAMETER CAST IN
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, replace it.
When Refinishing A Brake Drum - resurface the drum to a dimension no more than 0.76 mm (0.030 inches) less than the discard diameter. The
refinished 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 a better finish can be
obtained.
The Optimum Speed For Refinishing - braking surfaces is a spindle speed of 200 rpm. Crossfeed for rough cutting should range from 0.25 to
0.15 mm (0.010 to 0.006 inches) per revolution. Finish cuts should be made at crossfeed no greater than 0.05 mm (0.002 inches) 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.
