When refinishing a drum, remove only enough metal in order to obtain a true, smooth braking surface. If the drum does not match specifications after being refinished to the maximum refinish diameter, replace the drum. Refer to Component Specifications . Removal of more metal than necessary affects heat dissipation. This will cause brake drum distortion.

All brake drums have a maximum diameter. This is not a refinish diameter. Do not refinish a brake drum that will not meet the specifications. Replace the brake drum. Refer to Component Specifications .

When you refinish a brake drum, resurface the drum to a dimension no more than 0.76 mm (0.030 in) 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 wear.

Always use sharp cutting tools or bits. Dull or worn tools leave a poor surface finish. A poor surface finish will affect initial braking performance. Always use vibration dampening attachments when you refinish braking surfaces. These attachments eliminate tool chatter so that you can obtain a better surface finish.

Follow the manufacturer's instructions and recommendations for setting up and refinishing brake drums.

Crossfeed for rough cutting should range from 0.15-0.25 mm (0.006-0.010 in) per revolution. Make finish cuts at crossfeeds no greater than 0.05 mm (0.002 in) per revolution.

Do not refinish the braking surface when installing new brake drums. These parts already are at the correct level of surface finish.

Manufacturers use weights to balance brake drums. Do not remove these weights.

Check the drums for balance in the following situations:

Check the drums on off-vehicle balancers. Replace the drum if it is out of balance.