Cracked, Scored or Grooved
A cracked drum is unsafe for further service. Replace a cracked drum. Never attempt to weld a cracked drum. Smooth any light scores. Heavy or excessive scoring will cause excessive brake lining wear and it may be necessary to refinish the drum's braking surface.
For refinishing procedures, refer to Refinishing.
Out-of-Round or Tapered
A drum that is found to be out-of-round or tapered can be refinished to correct the condition if the condition is not too severe. Refer to Refinishing.
Refinishing
If a drum must be refinished, remove only enough metal to obtain a true, smooth braking surface. Replace the drum if a drum does not clean up when refinished to the following maximum inside diameters:
| • | 182 mm (7.16 in) for a 2-Door |
| • | 202 mm (7.95 in) for a 4-Door |
The removal of more metal will affect heat dissipation and may cause drum distortion.
When refinishing drums, always use sharp cutting tools or bits. Dull or worn tools leave a poor surface finish which will affect braking performance. Always use vibration dampening attachments when refinishing braking surfaces. These attachments eliminate tool chatter and will result in better surface finish.
The optimum spindle speed for refinishing braking surfaces is spindle 200 rpm. Crossfeed for rough cutting ranges from 0.25 to 0.15 mm (0.010 to 0.006 in) per revolution. Make finish cuts at crossfeeds no greater than 0.05 mm (0.002 in) per revolution.
After refinishing, replace any drum that exceeds inner diameter specification.
Balance
During manufacture, weights are used to balance brake drums. Do not remove these weights. After refinishing drums, check the drums for balance. Drums can be checked on most off-vehicle balancers. Replace drums that are out of balance. Refer to Vibration Diagnosis and Correction for additional information.
