Does Trailer Wheel Hub/Brake Drum Need to Be Replaced if Inside Surface is Grooved


hi i had to replace the brake assembly on a trailer because it seems that all the magnets got really hot because there was some wires that were meltted any why when this happend it left some grooves in the drum were the magnet makes contact will this affect the new magnet or should this contact area be really smooth.


Expert Reply:

Because the face of the magnet rides against the armature (inside) surface of the brake drum, any grooves that had previously been worn into the armature surface will cause the magnet to wear unevenly. For optimal braking performance, you want maximum contact between the face of the magnet and the armature surface of the brake drum. If the drum itself got too hot, you might see some blue discoloration on the armature surface. In extreme cases, the armature surface can warp.

It might be possible to find a machine shop that can surface the part of the drum where the brake pads ride, but not the armature surface. Shops that do this work are getting harder and harder to find. It might be more economical to simply replace the drum. You would need to find a replacement drum that has the same diameter and width, the identical bolt pattern and wheel stud diameter that is compatible with your existing bearings.

If your existing bearings are 25580 inner/ 14125A outer, and the drum you are replacing has a bolt pattern of 8 on 6-1/2, the wheel studs are 1/2 inch diameter and a drum diameter of 12 by 2 inches, the # 42866UC3-EZ would be the correct replacement. This drum includes the bearings, races, EZ lube cap and plug and double lip seal. The included seal has a 2-1/4 inch inside diameter. If you needed a seal with a 2-1/8 inch inside diameter, you would additionally need part # 10-10.

expert reply by:
Mike L

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