Rear hub is squeezing out its grease

[Bice]

Something is not right with my 10-speed Shimano Ultegra rear hub, which is 14 years old.

I have noticed that every time I repack the hub with grease an awful lot of it on the non-drive side gets squeezed out through the dust cap, quite quickly this days. And a big ball of grease forms.

I do put in a lot of grease, but the bulk of it is working itself out. The result is that the ball bearings remain quite lightly oiled, but you can hear them moving about quite loudly when you spin the wheel.

I think something is wrong. I am not over-tightening the cones: the wheel oscillates nicely and the fact that you can hear the bearings moving about quite loudly also indicates that they are not over tight.

I wonder whether the axle might be slightly bent, creating a spiral effect on the cone and bearings, which means the grease works itself out? Something uneven in the hub could be the cause, surely?

[NickJP]

Doesn't sound unexpected. I have some Campagnolo Record hubs with grease ports in the middle of the hub shell, and I periodically inject fresh grease in through the ports until grease comes out past the dust caps at each end of the axle, and I then wipe off all the excess grease. However, for the first few rides after this re-greasing, more grease comes out past the dust caps, which I wipe off. After a few rides, this stops happening until the next re-grease of the hub. I've had these hubs more than 20 years; this behaviour hasn't changed, and the bearings in the hubs are still fine.

[PT1029]

What was the hub like before you regreased it? Have you replaced the balls?
If you put a lot of grease in a hub, any excess will work its way out. A new Shimano hub has enough grease, but in fact not vey much (based on when I looked in a new XTR hub). You don't need masses of grease, at a minimum just need enough grease for the ball metal to be kept off the bearing surface metal.
Have you inspected the balls for wear (matt finish or nice and shiney)?. Ditto cone surfaces and hub cup surfaces for wear (pitting and/or wide ball track).
"The result is that the ball bearings remain quite lightly oiled, but you can hear them moving about quite loudly when you spin the wheel." - does not sound right to me - you should not "hear the balls moving about". I assume you have the correct number of the correct size balls (! - most of us have done this once at some point!)
"the wheel oscillates nicely and the fact that you can hear the bearings moving about quite loudly also indicates that they are not over tight" does not sound right to me. What do you mean by "oscilltaes nicely"? If it is the valve finding its own position at the bottom, then that is good.
Being a cassette hub, a bent axle is extreamly unlikely. If the axle is bent, it should be obvious if you turn the axle by hand when the wheel is out of the bike frame.
I assume there is no play at the rim, and the cassette body is still tightly bolted to the hub shell?
The only time I can hear "balls moving about" (at work), it is when a hub is correctly adjusted (or loose) and all the grease has gone over time and the bearing is dry.

[531colin]

I see a marketing opportunity here.
How about axle, cones, etc. all left threaded so the grease squeezes out of the driveside?
Or right threaded on the driveside and left threaded on the left side so all the mucky old grease migrates towards the middle of the hub?

[Brucey]

too much grease will come out of a hub, as others have said. I can only think of three circumstances in which I'd be able to 'hear the balls'

1) when there is something wrong inside
2) when there is no grease at all inside the hub.
3) if oil is used as a lubricant and the adjustment is slack.

BTW most cup and cone hubs are run overtight, The correct adjustment is usually to leave a little free play, that just disappears when the QR is tightened, due to elastic compression of the axle. You can use a stack of M10 washers each side as 'dummy dropouts' to see what the hub is likely to feel like in use.

[Bice]

What was the hub like before you regreased it? ABOUT THE SAME, BUT MAYBE GETTING A BIT WORSE. Have you replaced the balls? YES, ALL NEW BALLS.
If you put a lot of grease in a hub, any excess will work its way out. I DO PUT A LOT OF GREASE IN A new Shimano hub has enough grease, but in fact not vey much (based on when I looked in a new XTR hub). You don't need masses of grease, at a minimum just need enough grease for the ball metal to be kept off the bearing surface metal.
Have you inspected the balls for wear (matt finish or nice and shiney)? THE BALLS LOOKED OK, BUT I REPLACED THEM ANYWAY. Ditto cone surfaces and hub cup surfaces for wear (pitting and/or wide ball track). THE CONES I THINK I WOULD NOTICE PITTING. BUT AS I ALWAYS LEAVE DUST CAPS ON, I HAVE NOT REALLY EXAMINED THE RACES.
"The result is that the ball bearings remain quite lightly oiled, but you can hear them moving about quite loudly when you spin the wheel." - does not sound right to me - you should not "hear the balls moving about". I assume you have the correct number of the correct size balls (! - most of us have done this once at some point!) YES, I AM PRETTY SURE I HAVE DONE THIS CORRECTLY. I REPLACES ALL THE BALLS AND REPACKED ONLY A COUPLE OF MONTHS AGO BECAUSE I COULD HEAR MOVE: THEY ARE NOT RATTLING, JUST A NOTICEABLE CLICKETY CLICK.
"the wheel oscillates nicely and the fact that you can hear the bearings moving about quite loudly also indicates that they are not over tight" does not sound right to me. What do you mean by "oscilltaes nicely"? If it is the valve finding its own position at the bottom, then that is good - THIS IS WHAT I MEAN. I LIKE TO SEE A WHEEL ROCK BACK AND FORTH A BIT, OR OSCILLATE. IT IS USUALLY A BIT STICKY AFTER A LOT OF NEW GREASE, BUT IS STILL NOTICEABLE.
Being a cassette hub, a bent axle is extreamly unlikely. If the axle is bent, it should be obvious if you turn the axle by hand when the wheel is out of the bike frame.
I assume there is no play at the rim, and the cassette body is still tightly bolted to the hub shell? OK WILL CHECK THIS.
The only time I can hear "balls moving about" (at work), it is when a hub is correctly adjusted (or loose) and all the grease has gone over time and the bearing is dry. YES, THAT IS MY EXPERIENCE. I TOOK THIS BIKE FROM SAINT MALO TO THE DORDOGNE IN MAY AND NOTICED THAT I COULD HEAR THE BALLS. (I HAD REPACKED THE WHEEL IN ABOUT SEPT LAST YEAR, AND IT HAD A BIT OF WINTER USE.) WHEN I RETURNED FROM FRANCE, I REPACKED AND FITTED NEW BEARINGS. ALL SMOOTH AND FINE, UNTIL I PUSH OUT ALL THE GREASE AGAIN.

I am now getting a second opinion on the hub from a bike mechanic, and I will report back his assessment.

He did not think the hub was right when he took - a brief - look at it a week ago. At that point, the issue was complicated by the bike also having an obviously seized up rear derailler, which I have since stripped, cleaned and regreased. His judgement is usually very good, IMO.

[Bice]

The wheel, with its Shimano FH-6700, now has a new freehub body.

The boss of the bike shop, whose judgement I trust was not there, but diagnosis passed on was that the freehub was worn out.

Given this cost £70, an alternative approach may have been buying a new Shimano 105 hub from Spa and a new Mavic rim (this one does have a ding, has been well used and is 14 years old) for £80 all in and reusing the spokes for a completely new wheel. I may get these bits anyway, as 10-speed rim brake stuff becomes more obsolete.

[Brucey]

at £70 a go, it is almost certain that it would be worth rebuilding the freehub body.