Monte Carlo V6-3.8L VIN K (1998)
Brake Drum: Service and Repair
Brake Drum Refinishing
Inspecting and Refinishing Brake Drums Servicing the front brakes usually corrects pulsation in the brake pedal. Service the rear brakes only if the
problem persists. When removing the brake drums perform the following actions:
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Clean the brake drums.
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Inspect the brake drums for the following conditions:
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Cracks
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Scores
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Deep grooves out-of-round
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Taper Normal light scoring of the brake drum surfaces will not affect brake operation. Normal light scoring must not exceed 0.51 mm (0.020
inch) in depth.
CRACKED, SCORED, OR GROOVED DRUM
NOTICE: Be careful not to drop the brake drum during handling. An out-of-round condition can occur from even the smallest fall, which may result
in brake pulsation.
A cracked drum is unsafe. Replace any cracked drum. Do not attempt to weld a cracked drum.
Smooth any slight scores. Heavy or extensive scoring causes excessive brake lining wear. Refinish the drum braking surface if necessary.
Perform the following steps if the brake linings are slightly worn (but still reusable) and the drum is grooved:
1. Polish the drum with a fine emery cloth.
2. Do not refinish the drum.
Eliminating all of the grooves in the drum and smoothing the ridges on the lining would require the removal of too much metal and lining.
The grooves and the ridges will match if the grooves and the ridges are left alone. Satisfactory service can be obtained.
Refinish an excessively grooved drum if replacing the brake linings. A grooved drum will wear a new lining. The excessive wear will cause difficulty
when obtaining proper brake performance.
OUT-OF-ROUND OR TAPERED DRUM
An out-of-round or tapered drum prohibits accurate brake shoe adjustment. An out-of-round or tapered drum may cause excessive wear on other
components of the brake mechanism. An out-of-round or tapered drum may also cause the following conditions:
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Severe and irregular tread wear
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A pulsating brake pedal
Refinish the drum in order to true up the braking surfaces when the drum exceeds the specification limits in taper and/or out-of-round. Use the
J22364-01 or an inside micrometer fitted with proper extension rods in order to measure out-of-round and taper wear.
Measure for out-of-round and taper wear at the following locations:
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The open edge of the machined surface
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The closed edge of the machined surface
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Right angles (90°) to the above edges
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, replace the drum. Refer to Fastener Tightening Specifications. Removal of more metal will affect heat dissipation. Heat
dissipation may cause drum distortion.
All brake drums have a maximum diameter cast into them. The diameter is the maximum wear diameter and not a refinish diameter. Do not refinish a
brake drum which does not meet the specifications at the end of this section. Replace the brake drum if necessary. Refer to Component Specifications.
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 the 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. The 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.
Ensure that the finish cuts that were made at cross feed do not exceed 0.05 mm (0.002 inch) per revolution.