Polishing of bearing cups ?

[Rich2502Participant @rich2502]

Anyone have any ideas on how to resurface the bearing cups in bicycle wheel hubs ?

They are pressed in cups of hardened steel. Not sure if they are through hardened or case hardened the latter making this impossible, its not practical to fit new ones as spares are not available off the shelf except for a few vintage hubs.

This would have to be done while the hub was on the wheel as building a wheel is a long job.

[Rich2502Participant @rich2502]

[roy entwistleParticipant @royentwistle24699]

I seem to remember this from last month

Roy

Edited By roy entwistle on 06/09/2018 16:15:14

[David Standing 1Participant @davidstanding1]

Here, but not the same question:

**LINK**

[Michael GilliganParticipant @michaelgilligan61133]

I am almost certain that they are only case hardened … but it should be a very simple matter to check.

• Take one scrap cup, and a triangular 'diamond needle-file'
• File a nick in the edge of the cup
• Take a good sharp hacksaw
• Attempt to saw the cup

Alternatively, if you have any sort of grinder …

MichaelG.

[John OlsenParticipant @johnolsen79199]

I'm not sure that you will have much luck in resurfacing old cups.

I would be looking at a few other possibilities:

1 Is there a more available type that is just a little smaller? That might let you fit a sleeve into the hub to bring the hub down to the available size. You would probably want to use the matching cones, which may or may not fit the axle, although all the ones I have seen seem to be about the same diameter.

2. If the only modern replacement is just a little too big for the hub, you could look into resizing the outside of the cup. This would require something like a tool post grinder. They are of course not all that thick, but you could probably get away with reducing the outside diameter by a millimeter or so.They are probably too hard to turn. You would want to protect the inside bearing surface from grinding sparks.

3 What about coming up with a fix using cassette type bearings, eg standard ball bearings fitted into the hub. This might also require a sleeve in the hub to bring the size down to an available bearing size. It would also require a suitable piece for the axle to replace the cone. This bearing would need to have an inner diameter larger than the axle, and you would make up a piece threaded to fit the axle and with an outside to fit the bearing, plus a larger step with flats to allow adjusting it up to trap the bearing.

I have done the resizing trick on motorcycle steering head cups and cones, when fitting a Suzuki 185 front end into my Honda 100 years back. It means that the only parts you change are not the actual bearing surfaces, so it does not matter if you take off any case hardening.

John

[Neil WyattModerator @neilwyatt]

Is it really worth the effort, if the original hubs are not special in any way?

It doesn't cost a fortune to get a wheel rebuilt. My brother builds wheels (he built the ones on my mountain bike) and says anyone with the patience and care can do it. Although it's a long job for a beginner, it's not going to take days. Taken carefully it's very rewarding and if you use the frame as a jig the only costs are the new hub and a decent spoke key.

Neil

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Neil Wyatt on 07/09/2018 09:42:10:

Is it really worth the effort, if the original hubs are not special in any way?

.

Quoting from the opening post: "its not practical to fit new ones as spares are not available off the shelf except for a few vintage hubs."

… My inference from this is that the original hubs are special in some way.

MichaelG.

[HopperParticipant @hopper]

You might be able to set them up running true in the lathe and use a toolpost mounted Dremel grinder, or similar, with a spherical stone the same diameter as the balls to regrind the race.

We use this technique to regrind the ball races in vintage Harley hubs that are made as one piece, ie not removeable.

If the races are case hardened you will have to try to not grind through past the depth of the case.

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