Is Brown Discoloration on 3,500 lb Trailer Spindle OK

Updated 09/07/2023 | Published 09/06/2023

Question:

Im sure this is being to OCD. When I repack the bearings on my 3500lb axle the spindle always has and has always had some brownish discoloration on the underside. My understanding is that this is fretting and is normal. It could also be caused by storage. EG. Discoloration/ problems with the ROLLER BEARING are concerning but the spindle will discolor underneath and unless is grooved/damaged that fretting is normal. Question. Should I leave that fretting there? Or sand it off? It feels perfectly smooth. And what would you sand it off with anyway? Ive always left it. As my understanding is that some movement between the inner race of the bearing and that spindle is acceptable on this axle. And that the Roller Bearing is actually what does the work. Races on the hub all look great FYI. Thanks for any advice! The internet does not have this very particular answer and you guys are the pros!

asked by: John S

Expert Reply:

Definitely smart to check, and you're right that the brownish discoloration on your 3,500 lb trailer spindle like # TRU24FR is perfectly normal. Just the discoloration won't be an issue, and you can leave it be as that is just caused by heat and grease. The only issue would be if it was grooved or nicked somehow, but since it's perfectly smooth like you said, then the spindle is fine.

expert reply by: Kyle S