G 2500 3/4 Ton Van V8-305 5.0L VIN M SFI (1997)
Brake Drum: Testing and Inspection
Refinishing
NOTES ON REFINISHING PROCEDURES
If you determine a drum needs refinishing, remove only enough metal to obtain a true, smooth braking surface. If a drum does not clean up when
refinished to the maximum refinish diameter 331.72 mm (13.06 inch), replace it. Removal of more metal will affect heat dissipation and can 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. Replace, do not refinish a brake drum that will not meet specifications. When you refinish a brake drum, resurface the drum to a
dimension not more than 0.76 mm (0.030 inch) less than the discard diameter. The refinish diameter is the maximum diameter the drum can be
refinished to and still allow safe braking action. If you exceed this diameter, the brake drum will wear beyond the discard diameter during normal
brake use.
NOTES ON TOOL USAGE
Always use sharp cutting tools or bits. Dull or worn tools leave a poor surface finish that will affect initial braking performance. Always use
vibration dampening attachments when you-refinish braking surfaces. These attachments eliminate tool chatter so you can obtain a better surface
finish. The best speed for refinishing braking surfaces is a spindle speed of 150 RPM. Cross-feed for rough cutting should range from 0.15 to 0.25
mm (0.006 to 0.010 inch) per revolution. Finish cuts should be made at cross-feeds no greater than 0.05 mm (0.002 inch) per revolution.
