Pitting in cups and cones - any tips?

I'm currently servicing my Scott's M730 hubs. The spokes needed to be replaced and the hubs themselves had lost all their shine, so I figured I'd polish them and overhaul the bearings.

The rear was still running perfectly smooth, the front not so much.
Upon taking them apart, I noticed that both hubs have pitting on the non-drive-side. This is on the axle cones as well as the hubs themselves.





Funnily enough, the rear appears to be in much worse shape than the front is. I guess the front was a bit overtensioned by the LBS who overhauled them last time, causing it to be more apparent.
Both sides felt perfectly fine while on the bike, it's only when taking them out and twisting the front axle by hand that I noticed the problem.

Any tips on dealing with this?
Replacing the balls themselves isn't a problem, I have access to those. The cones shouldn't be an issue either. But the cups are a different matter. I'd hate to have to throw these hubs in the trash, it's hard to find them in 32h flavor nowadays.

Re:

I ran into the same problem myself, same type of hubs. Hubs are pretty well toast, as the internal bearing surfaces cannot be replaced. The only thing you can try, if I'm not mistaken, is to pick up a fine grit material available on the market (forgot what it's called), and try to resurface the races using that ... although that will simply abrade yet more of the hardened race surface away (thus hopefully giving you s smoother surface).

I suppose it depends on how badly they're pitted, really.

Depends on how much you ride on these. Personally, I'd fit new bearings and grease and not worry about it.

legrandefromage":1g474mg0 said:

Depends on how much you ride on these. Personally, I'd fit new bearings and grease and not worry about it.

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The last few years I did about 3-4000 miles per year on that bike, but I plan to at least double that once it's been rebuilt.

k-rod":1g474mg0 said:

The only thing you can try, if I'm not mistaken, is to pick up a fine grit material available on the market (forgot what it's called), and try to resurface the races using that ... although that will simply abrade yet more of the hardened race surface away (thus hopefully giving you s smoother surface).

I suppose it depends on how badly they're pitted, really.

Click to expand...

Lapping compound may be an option indeed, at least for a temporary solution. Lap the cups, rebuild the wheels and start looking for an alternative while riding these until it really becomes problematic.

Re:

8000 miles a year warrants replacement to me. Interested to hear how you get on with lapping them. Bit of grinding paste in grease and ride for a week?

Smoothing the surface is a complete waste of time. You will never ever get it right, even using a lathe. Plus the surface is hardened. Technically, the inner cones can be pressed out and replaced, but why would you bother?

Just buy another pair and thats it. Or do as LGF said. I did that, too on my commuter. Those hubs will continue to run OK for quite some time....

Lapping is pointless, you wont get the pitting out just trash what is left of the hardened surface.

Replace the cones, they are smaller area plus remain fixed so any uneven wear will be exagerated. New ball bearings, grease and ride them.

Just a thought, it may be possible to press or pull the old bearing out then get hub machined to take one of the new fangled sealed races. You would need matching axle made up..... but almost certainly be cheaper to buy replacement.

Re:

Yes it seems like those hubs are at the beginning of the end of their useful life.
As already said above, replace the axle cones, fit new bearings, grease, and ride.
They could well last another year or more, but ultimately it'd be easier to search for some more of the same hubs, rather than try to repair the damage to the current ones.

Re:

Too bad you just can't find these new in 32h anymore.
Buying 2nd hand is always a risk, it's a paypal dispute and a forum argument waiting to happen.

I'll just rebuild these wheels (with new spokes, some were bent) and ride them until they go bad. In the meantime I'll get me some NOS hubs in 36h flavor and be on the lookout for some NOS 36h rims.