Will a corroded sprocket damage the hub oil seal?

[expr]

Ok no problems, I will try and help as much as I can, but its inportant to clean the area and find the source >

Speak soon

Dave.

[goosander]

OK, I cleaned up the hub and added a bit more oil to it and then went for a 5 mile cycle.  The good news is that the hub is now quieter, so I think the change in freewheel noise was due to the hub being almost empty as you suggested.  It is now apparent that the oil is leaking from the driver bearings and not the sprocket oil seal - the area around the driver nut became moist with oil after only a couple of minutes of cycling.

So it looks like I need to replace the driver bearings - how hard are these to remove and is there anything I should be aware of?

Expr, you mentioned that it is possible for oil to leak past the driver bearings rather than past the oil seal, how do you stop this?  Should some sort of sealant be used to 'glue' the bearings to the hub?

Before deciding whether or not to do this, I will give SJS a ring and find out how much they will charge.  I really need a new rear rim anyway so it could be tempting to get both done at the same time, especially as SJS seem to do a good job on wheel building.

[geocycle]

Sorry to hear you are having trouble.  Your suggestion of returning the hub to SJS seems sensible.  I sent mine back last year for building into a new rim and reversing the sprocket.  I simply cut through the old spokes and sent the hub.  Came back within a few days. 

[goosander]

SJS say it will need to go back to Rohloff but can't say how much it will cost other than it would be 'fair' with the possibility that Rohloff might take pity and fix it for free.

[geocycle]

Let us know how you get on.  I hope Rohloff's legendary service lives up to expectations and I hope it is not that expensive to send to Germany with DHL or whoever.  I guess it would still be worth having a new rim while it is out of the bike and make it easier to post.  FWIW I rate SJS's wheel building very highly. 

[expr]

Hello goosander,

sorry for the late reply I've had rather bad news to deal with. The driver bearings are pressed in to the driver itself with no sealent around them and only relying on the interference fit to create the seal, they are very easy to change but you are doing the right thing sending them back if unsure. The two driver bearings are in back to back inside the driver effectively giving 4 seals to get past which I have to say is pretty much impossible.

I would be tempted to say its coming from the shifting shaft seal which rohloff call the (breather) which inturn goes in to the hollow part of the axle where the qr goes through. Did you check to see if inside was also wet with oil.

I hope you get sorted out, let us know what rohloff said the issue was.

Any more questions please ask.

Dave.

[goosander]

Hi Dave, sorry about your bad news, I hope whatever it is can be resolved.

Anyway, I decided to send the hub back to SJS and get them to sort it as I needed a new rim anyway.  They rang me last week to say that they have fixed the hub (no need for it to go back to Rohloff) by replacing a seal which from what they described on the phone sounded rather like the shifting shaft seal you mentioned.  The repair was done free of charge (thanks SJS) and they have apparently replaced all of the easily accessable seals as a precaution.

I hope that this sorts the problem but I have a nagging doubt because there was no sign of oil on the QR skewer (it was bone dry) which you would expect if the shifter shaft seal was leaking.  Guess I'll just have to wait and see, hopefully the wheel will be delivered in the next day or two - now just need to get the frame fixed...

Whilst the hub was being repaired I decided to get the frame blasted and re-powder coated as the original finish was getting very tatty.  Unfortunately the local firm I used haven't been very careful and managed to put three small dents in the frame, as if that wasn't bad enough they also powder coated over the Thorn badge on the head tube rather than remove it prior to coating which they told me they would do.   

[expr]

Hi goosander,

If the qr pin was dry then the shifting shaft seal is definitely not the cause, and sjs would not go that far with the strip down, that would have gone to germany. The only seals accessible are the main hub lip seals which they would have done I guess and possibly the driver bearings but again I don't think sjs go that far either.

The lip seal could have been the cause and is the most probable, the driver bearings shields are very difficult to pass oil as I said there are four to get past, and the chance of the oil passing around the outside of the bearing cage is almost none.

Similar to a car engine, oil leaks can come from a totally differnet place than where they are dripping from. I realise as you said that you cleaned it all off and found fresh oil on the aluminium nut allmost straight away which would suggest the main oil seal to have gone given the quick hemeraging of oil.

I would be tempted to ask them to get the dents put right and the badge sorted out. what material is the frame, can it be braze filled and re-coated.

[goosander]

SJS said that they didn't replace the driver bearings but did replace the lip seals even though they weren't the cause of the leak.  Guess I'll just have to wait and see whether or not it is really fixed.