Bicycle Mechanics - Polishing bearing races
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07-23-09, 06:54 AM
I have a classic PX-10 that has some damage to the races in the hubs, and wanting to keep it all original I plan to polish them and save them if possible. Can anyone tell me the material that the bearing races are made of? Is it just steel, or is it stainless steel?
07-23-09, 07:11 AM
I'm certain the races are plain carbon steel but if you use a suitable polishing/grinding compound it wouldn't matter what type of steel they are.
07-23-09, 07:53 AM
Bear in mind that if you have pits you'll have to take out a lot of material, at which point you may end up going through the hardened section. There's a how to somewhere on the internet where someone else did the same thing.
What sort of damage are you seeing? If the races are galled then they are basically toast. No amount of repair is going to be easy or inexpensive. And even if you were successful in smoothing the race, in all likelihood the geometry of the race will have slightly changed and if so, you will likely need to replace the ball bearings to a new size. If you look around you can find the Normandy HF hubs (used),that were commonly original to these bikes. That might be the better path for you. Of course, that means lacing and/or lacing and dishing a wheel - are you up for that?
If all you are seeing is some staining (dark spots) just steel wool it (#000 or finer) until you have a smooth surface. The stain won't hurt anything. Be sure to use a good grease when you repack the hubs. What qualifies as a "good grease" is a religious war that I won't get into, but any common bicycle grease will do.
07-23-09, 10:11 AM
What qualifies as a "good grease" is a religious war that I won't get into, but any common bicycle grease will do.
I.e. "not Vaseline or bacon grease." :)
07-23-09, 10:38 AM
I've polished up a BB spindle that was discolored from rusted bearings. Took some fine sandpaper wrapped around a 1/4" bolt (same diameter as bearings) and spun the spindle on a lathe. Worked quite well. Hub cup races will be harder, though, since the part you want to get at is up in the hub. If you're only removing a very small amount of material, the curvature of whatever tool you use isn't too important if you go slow. You won't change it enough to really make a difference. I would make sure to do this on a rotating tool of some kind (lathe, drill press...) to make sure that the grinding is even around the circumference of the hub. If there's a low spot where you ground the race down it'll basically be worse (or make itself worse) than you had it before.
07-23-09, 01:11 PM
I've often wondered what Simichrome would do for the races in hubs & BB's.
07-23-09, 01:37 PM
What, no bacon grease? Folks have complained that my bikes smell bad...
I think the above post is correct; if you have actual pitting or galling, then the damage has extended down past the hardening of the cone. Even if you succeeded in polishing the damaged area out, likely it would wear rapidly. I imagine you'd need a precision lathe to do the work with.
07-23-09, 02:17 PM
I've heard that you can do a bit of polishing by packing the bearing with simichrome and spinning the axle with a drill. After that, toss the balls and put new ones in.
As others said, if the damage is really bad, no polishing will help.
I use bearing grease from the auto parts store. It's true that your choice of grease is a religious matter, and I respect most people's choices.
I suspect Vaseline will work better than bacon grease, because the latter is pretty solid until heated, then it becomes thin liquid. Also, dogs will chase you because of the odor the bike will have.
07-23-09, 06:24 PM
I'm of the opinion that leaving the pits, repacking, and repacking more often in the future would be a better solution than trying to restore a pitted race by removing the hardened layer.
07-23-09, 06:30 PM
i'm not saying this works because i've never tried it: some of the more seasoned mechs at my shop have told me that they've packed pitted hubs with some abrasive toothpaste and rolled around for a while. they say it works well enough to eliminate the shallower blemishes.
needless to say, the hub gets new balls and grease.
I think Simichrome would make it shine and that is about all, as it has no cutting action to speak of. There are lots of high-speed abrasive compounds readily available from any automotive supply house that would make the job faster and smoother. What kind of a tool you could use with such a compound, how you would insert it and what you would use to (presumably) turn the tool is a beast of a different nature. Most automotive machine shops would have the skills to answer that question I am confident.
07-24-09, 05:33 PM
Just to be clear, do you mean the hub races, or the cones? In my experience the cones generally go before the hub races (I suppose due to the smaller circumference). You might be able to find replacement cones if you try a few shops. If it's the hub races, I agree with DIYGUY that new hubs are in order.
07-24-09, 07:15 PM
Just to be clear, do you mean the hub races, or the cones? In my experience the cones generally go before the hub races
That's been my experience also. I've seen the cones from several makes of hubs damaged from contamination, neglect and/or poor bearing adjustment but never seen one with the cup race damaged.
Replacement cones, either the exact OEM replacement or a "will fit", are widely available and can restore a damaged hub to like-new operation.
07-27-09, 05:36 AM
OK here is what I did, I took my dremel tool with a polishing disk which I cut down to slip inside the cup and a cake of emory paste and went to work. I was able to polish away most of the damage in about 15 minutes. I replaced the ball bearings and gave them fresh grease. They spin nicely now, these wheels go on a vintage PX-10 restoration which probably won't be ridden very hard so I am not too concerned with any longevity issues.
Sounds like a very nice solution and a thoughtful approach to a difficult little problem. Thanks for sharing!
I also have a PX-10 that I just finished. I rode it to the store last weekend. It has been about 10 years since I rode it, and what a ride compared to my aluminum "wonders". Anyway, I have an extra Normandy hub if you need some races.
08-03-09, 05:14 AM
I am in need of a rear axle for a Normandy Hub if you have one.
08-03-09, 07:20 AM
I picked up an old Raleigh MTB as a pub bike. As is my custom, before I rode it, I stripped everything down to give it the once over. The hubs are aluminium, and quite attractive for what is obviously a low-end bike. On opening up the front hub, I was surprised to see what looked like fresh grease, as the bike otherwise appeared to have been neglected for a long time. Anyway, I cleaned and re-greased the front hub, and it spun (span?) beautifully. The rear likewise had fresh grease in the hub on the non-drive side. I unscrewed the block, and the drive side was a different story. There was a potent cocktail of old grease, dirt, water and rust. Sadly, on cleaning it out, the race and cone on that side were badly pitted, at one part of the circumference only. I wondered if I could pack that side with the coarse automobile engine valve grinding paste, which is just grease and abrasive particles suspended in it, ride it around for a bit, then replace the ball bearings. I'm not sure how much of the cup race you could remove safely. An alternative to riding it with the hub packed with grinding paste would be to simply do the job on the bench and rotate the spindle. Anyway, I'm running it as it is, and it's not too bad. It figures that, if a hub is aluminium, the steel bearing cups must be pressed in somehow. Can they not be replaced?
08-03-09, 08:05 AM
It figures that, if a hub is aluminium, the steel bearing cups must be pressed in somehow. Can they not be replaced?
They are either pressed into or cast into the hub shell and, in theory can be replaced. Doing it is another matter. Replacement races are available for some Campy hubs but Shimano and most others don't offer them.
08-03-09, 08:29 AM
A variety of solutions exist for refurbishing cones and races.
Removing rust marks or similar type staining is easy. all you have to do is find a creative to polish the questionable pieces. I polish axle cones on my buffing wheel and polish hub cups with a buffing pit on my Dremel or reuglar drill.
Anything more than surface contaimination CANNOT be fixed by polishing. Any pitting or cracks must be adressed differently. Back in the old days some of the guys would mount their cones in a lathe and cut them down until a smooth surface was present. As others previously mentioned this isnt a good idea becasue your maching away the hardened surface, it only works if the cone is harded all the way through. The best course of action is to find a new cone. Hub races are a different story. I recently had one with very severe rust damage that couldnt be polished out. I replaced the race with one from a hub with a damged shell.
I am in need of a rear axle for a Normandy Hub if you have one.
Unfortunately, the hub I have is a front hub or you'd be welcome to the axle.
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