Tech Hub cups gone bad?

baribari

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May 28, 2010
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#1
After three and a half years and only about 1500 km, something has gone wrong with my hub bearings, it seems, since they were dragging.

I opened up the fronts and this is what I found:

What is with these two protrusions on the bearing cup? They're on both sides.

There seemed to be some damage to the interior of the lip, which I think was the primary reason my hub was dragging.

I broke a spoke on my rear wheel, so I decided to replace it (it's always been a problem, anyway), but I'd like to just replace the hub on my front if possible. Do they actually sell these? Or should I go ahead and order a new front wheel?
 

GSAstuto

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#3
Shimano considers the cups non-replaceable. Shimano doesn't sell any of the straightpull versions separately (as far as I know) . You can get the guts (axle, cones, seals, bearings) , but not the shell or cups. With that being said, you might be able polish out the brinelled ridges enough to be servicable, though, if the hardened layer is worn through they'll just end up the same way in a short time. Another option is replace the steel balls with ceramics which will slightly 'heal' the worn surface, due the much harder ball vs cup.
 
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baribari

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#4
Can you tell me why the cups have two protrusions sticking out of them? I could understand if they had a groove cut into them from lubrication starvation, but not protrusions.

Are the cups supposed to have a lip on the inside (to keep the bearings in place, I take it?). That lip is damaged, so I wonder if I could get away with removing the rest of it.

I was afraid that I wouldn't be able to buy a new shell/cup, since it wasn't listed on the parts list.
 

AlanW

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#5
They appear to be artefacts from the manufacuting process. The steel cup is pressed into the alloy hub shell. Maybe the machine that does this holds the steel cup where the protusions are. Looking at the wear track, it seems the balls don't contact these at all. I don't expect there to be a significant lip on the inside of the cup; if there is I would clean it up with some emery paper, then douse everything with acetone to remove any swarf, then re-grease, assemble, and adjust.

By the way I have the exact same front hub (RS80-50CL) and the bearings were significantly over tightened from new. I had to adjust them to get the hub to run smoothly, but after 3000 km it's running sweetly now. The QC on these wheels seems a bit lacking compared to the Dura Ace series.
 

baribari

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#6
It is possible that they aren't touching the protrusions.

What do you mean by don't expect there to be a significant lip?

There is a fairly substantial lip on the inner diameter of the cup that is big enough to catch a finger nail. I wonder if this comes from wear, of it was machined with a lip to begin? I think the damage to the lip (which is only on one side (the one pictured) and right next two the protrusions.

I don't suppose you can remove the cups with a bearing puller slide hammer? Well, you probably could, but it would do you no good without new ones...
 

AlanW

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#7
OK, but a lip in that position should not be touching anything, unless the ball bearings were in pieces when you removed them, which I assume they were not.
This is how a cup-and cone runs when assembled (this is a BB, but hubs are the same)
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There should be nothing touching area where the lip is, which leads me to believe it is just a leftover from manufacturing. If the cup is stamped, which is likely, you could get a small ridge.
I don't suppose you can remove the cups with a bearing puller slide hammer? Well, you probably could, but it would do you no good without new ones...
Do NOT do that ;)
Try assembling it dry (no lube) and see how it feels.
 

baribari

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#8
When it's dry and tightened to the appropriate level of play it doesn't want to rotate at all.

When lubricated with fresh grease it seems to be dragging on one spot every turn.
 

AlanW

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#9
Does rather sound like it's knackered then. Maybe time to get the file/emery paper out and try to clean up the lip. At this point you've probably nothing to lose.
 

GSAstuto

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#10
The 2 'dots' are from the swaging press. Steel cups in alloy hub. So they can avoid high tolerance and prevent the cup from shifting - it's a common technique to anchor the cup. Again, you might be able to polish out the worn ridges (commonly known as brinneled grooves), but these are case hardened cups. If the wearing has gone much into the hardened surface then don't expect much lifetime as the balls will simply grind away at the softer material. With that being said, I've seen many hubs being ridden constantly in worse condition. Generally speaking the cones will take more beating (and are replaceable). So why not just get a set of cones and new balls and then try it? Get a bit of Lithium or Flouro based grease (like Finishline) and you'll be fine.
 

baribari

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#13
Yeah. But I make a point not to shoot high-pressure streams at any areas with bearings.

FWIW, it's not as if my last bearings had lost any grease. I suppose its possible the grease had been contaminated.

I might actually still be within the warranty period, but I don't have the receipts and the shop I bought it from has gone out of business.
 

baribari

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#15
Took it back apart again to replace the bad bearing and it turns out one of the cones is pitted. Weird. I didn't notice that before. Guess I might as well older new cones and bearings.