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WHAT MAKES A GOOD BRAKE DRUM (continued)
WHEN SHOULD A BRAKE DRUM BE REPLACED?
The ability of a brake drum to perform safely is affected by a variety of factors. Conditions, which affect the life of brake drums, are
listed, although this list is not intended to be all-inclusive it should serve as a useful guide. The brake drum should be replaced when
any of these conditions appear.
1. Brake face diameter reaches maximum limit
2. Excessive heat checks
3. Cracks
4. Martensite spotted drums – “hot spots”
5. Worn or elongated bolt holes
6. Galling of brake surface
7. Brake drum known to have been overheated as occurs with dragging brakes
8. Brake drum warped….out of round
9. It may be necessary to replace brake drums in pairs in order to maintain proper brake balance and efficiency.
RECOMMENDATIONS FOR LONGER BRAKE DRUM AND ROTOR LIFE
When drums are forced to fit onto a hub, there is improper match of parts for installation. The cause must be determined and corrected.
Wheel bearings should be properly adjusted to prevent the drum from picking up the load created by the braking action.
Drums and linings should be checked at periodic intervals to detect operational patterns. The use of non-asbestos organic linings can
cause linings to swell and drag resulting in hot spots and lower fuel economy.
Clearance between non-applied brake linings and the drum varies slightly. See the brake system manufacturer’s recommendations for
this adjustment. Proper clearance prevents excessively hot linings and drums and improves fuel economy.
Parking brakes should not be set while the drums are hot. Allow them to cool, otherwise, drum cracking and failure can result.
DRUM FAILURE ANALYSIS
Regular and thorough inspection of your brake system is the best investment you can make for low cost per mile brake operation. Be sure
you have a standard inspection timetable and follow it. The following pages list common problems you should be alert for.