I'm working on a Deore XT M737 front hub. When I took it apart it was completely dry and the balls, cups and cones were coated in a hard, matt black substance which I assume is some sort of compacted grease / dirt residue. It came off the cones quite easily with WD40 and a brass brush - underneath they were heavily pitted, but they can be replaced so I'm not too bothered. I've had a much harder time trying to get it off the cups, as the attached image shows. I'm wondering if anyone has encountered this before, and is there any known way of getting the stuff off?
Weirdly the matching rear hub was absolutely immaculate inside, despite the outside being caked in 25+ years of dirt.
(Hmm, not sure why the image embed function isn't working, here's the link...)
Tried wore wool or similar? TBH I expect they'll be as pitted as the cones.
Just get a similar Shimano hub and re use the cups from it.