FD pinion bearing seal

Slipperyeel · Jul 24, 2020

Afternoon all.

I'm off to Italy in Monday. Ahead of this I wanted to give the FD gaiter a check because on my earlier trip a few weeks ago (some of you may remember my post on this) my preparations revealed a load of water in the shaft tunnel - the calcium grease of used had all but washed away. So I purchased some Staburags grease.

Then, on my ride down to the tunnel, the rain was horrendous. I needed a bloody snorkel. Lol. But consequently I was keen to see how the Staburags had held out.

Well, I have to say, what a result

. Clearly a really good seal remained despite the rain and the following heatwave.

However, what I did find was some oil around the pinion shaft. FD oil. Some pics below. When I drained the oil to lower the FD, it had a wispy black appearing here and there, otherwise it was beautifully clear. My thinking is, a seal is breaking down. And now I see the trace of oil around the pinion shaft, I'm joining dots and thinking it must be the pinion seal.

I'm not overly worried. Not enough to stop me doing this return trip. There's no play in the rear wheel. But clearly it's going straight to Mikeyboy when I'm back!

Thought it might be of interest.

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NicD · Jul 24, 2020

is there much play in the pinion?

Slipperyeel · Jul 24, 2020

NicD said:
is there much play in the pinion?

I think there is. But I'm not sure. I mean, if there is, I can barely feel it - to the point I'm not sure it's play I'm feeling!

Right now my guess is the seal is on the way out. So it's going to need a rebuild...when I'm back. I've just done 3k on It since the last fluid change. Little difference on any details except for the tell tale wisps in the otherwise clear oil and now this weeping from the pinion.

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Advsplash · Jul 25, 2020

Thanks for sharing, good to see for the brain bank.

Just had my FD back from Mikey, very slight play in the pinion on inspection, though no oil... perhaps a matter of time, perhaps not.

How long since your last FD rebuild? surely not 3k?

Slipperyeel · Jul 25, 2020

Advsplash said:
Thanks for sharing, good to see for the brain bank.

Just had my FD back from Mikey, very slight play in the pinion on inspection, though no oil... perhaps a matter of time, perhaps not.

How long since your last FD rebuild? surely not 3k?

3k since last oil change. I only changed it this time so I could lower the FD. My intention was to check and see how the Staburags had performed (very well from what I could see!). But because I left it like new in there, it was easy to see any changes. And no water this time!

But the oil is a good indicator of things going on inside there. In my case, normal wear excluded, it looks good in that there are zero metal particulates. But there is some black wisps of something, almost another liquid. My educated guess is oil seal breaking down. That, combined with the weep from around the pinion shaft, if guess it's the pinion seal. I reckon it was doing it when I found the water in there 3k ago because there was a lot of emulsified oil around the whole area. Maybe it's all a consequence of water getting in there in the first place, allowing a tiny bit of corrosion around the dust where the seal lips meet? Not sure, but it seems a reasonable idea.

But it's now on borrowed time. A rebuild is clearly needed.

I'll report back after this next trip. But my thinking is, next to nothing has changed since I was in there last. I can just see something 'new' because it's free of water.

I think play in the system is acceptable, but it should be really really tiny.

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Lowflyer · Jul 25, 2020

Could this be a leak in the final drive seal as oppose to the pinion seal ?

Slipperyeel · Jul 25, 2020

Lowflyer said:
Could this be a leak in the final drive seal as oppose to the pinion seal ?

Not sure how that would allow oil to reach the outside of the pinion shaft?

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Lowflyer · Jul 25, 2020

Slipperyeel said:
Not sure how that would allow oil to reach the outside of the pinion shaft?

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Down the inside of the paralever.
Maybe check for any oil deposits at the bottom of the paralever housing.
I may be well off the mark, just a suggestion

bikenav · Jul 27, 2020

From my experience of a a Gearbox output seal failure the oil dripped out of the main swing arm beautifully shining up the rear tyre and I was in the Alps at the time, ended up with piles of paper towels etc taped around the swing arm, good talking point anyway.

Advsplash · Jul 27, 2020

Slipperyeel said:
3k since last oil change. I only changed it this time so I could lower the FD. My intention was to check and see how the Staburags had performed (very well from what I could see!). But because I left it like new in there, it was easy to see any changes. And no water this time!

But the oil is a good indicator of things going on inside there. In my case, normal wear excluded, it looks good in that there are zero metal particulates. But there is some black wisps of something, almost another liquid. My educated guess is oil seal breaking down. That, combined with the weep from around the pinion shaft, if guess it's the pinion seal. I reckon it was doing it when I found the water in there 3k ago because there was a lot of emulsified oil around the whole area. Maybe it's all a consequence of water getting in there in the first place, allowing a tiny bit of corrosion around the dust where the seal lips meet? Not sure, but it seems a reasonable idea.

But it's now on borrowed time. A rebuild is clearly needed.

I'll report back after this next trip. But my thinking is, next to nothing has changed since I was in there last. I can just see something 'new' because it's free of water.

I think play in the system is acceptable, but it should be really really tiny.

Sent from my SM-G975F using Tapatalk

Looks like the Staburags has worked wonders, I'm yet to re-assemble my bike because the newborn just sucks up all the time :comfort

but I think I'll source some... I really don't want to have to replace / repair it again anytime soon!

When I dropped the oil in my FD it was black, very very black, and smelt awful, though tranny oil smells anyway this was just amplified to a point of wanting fresh air.

Agree on the being able to see something new, this oil could be a week old or month old problem, just keep a sharp eye on it and let us know how it goes!

NicD · Jul 27, 2020

Advsplash said:
When I dropped the oil in my FD it was black, very very black, and smelt awful, though tranny oil smells anyway this was just amplified to a point of wanting fresh air.

That's doesn't sound great. Even if it had just been rebuilt, it wouldn't be as black as you describe or smell as much. Or am I wrong?

Advsplash · Jul 28, 2020

This was about 3k after a rebuild, not by Mikeyboy I'd like to state.

There was no transparency in the oil whatsoever, I just believe it was from the pinion needle bearing wearing but :nenau

FD pinion bearing seal

Slipperyeel

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NicD

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Slipperyeel

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Advsplash

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Slipperyeel

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Lowflyer

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Slipperyeel

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Advsplash

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NicD

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