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Drums

Determine the need to recondition based upon individual drum conditions that follow. Friction material replacement does not require drum reconditioning unless other justifications exist. Do not recondition new drums unless they are being pressed or bolted onto an existing hub. It is not necessary to replace drums in axle sets. However, when replacing or reconditioning a drum due to the conditions that follow, you may suggest reconditioning of the other drum on the same axle to eliminate uneven braking behavior. Always wash drums with warm soapy water and a clean cloth after servicing or before installing.

Condition	Code	Procedure
Balance weight missing		No service suggested or required
Bell-mouthed, affecting performance	A	Require reconditioning or replacement
Cooling fin broken		No service suggested or required
Cracked	B	Require replacement
Drum diameter is greater than OEM "machine to" specifications but less than "discard at" specifications, and the drum does not require reconditioning	1	Suggest replacement
Only applies to vehicles for which OEM "machine to" specifications , the drum may be worn to discard specifications exist. If OEM does not supply "machine to".
Drum diameter will exceed OEM "machine to" specifications after required reconditioning	1	Suggest replacement
If OEM does not supply "machine to" specifications, you may machine to discard specifications.
Hard -spotted	2	Suggest reconditioning or replacement
Measured diameter is greater than OEM discard specifications	B	Require replacement
Out-of-round (run out), affecting performance	A	Require reconditioning or replacement
Out-of-round (run out), exceeding manufacturer's specifications	B	Require reconditioning or replacement
Scored	B	Require reconditioning or replacement
Surface threaded due to improper machining	B	Require reconditioning or replacement
Tapered, affecting performance	A	Require reconditioning or replacement


Legend
A	Part no longer performs intended purpose
B	Part does not meet a design specification (regardless of performance)
C	Part is missing
1	Part is close to the end of its useful life (just above discard specifications, or weak; failure likely to occur soon, etc.)
2	To address a customer need, convenience, or request (to stiffen ride, enhance performance, eliminate noise, etc.)
3	To comply with maintenance recommended by the vehicle’s Original Equipment Manufacturer (OEM)
4	Technician’s recommendation based on substantial and informed experience




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