ATF seeping onto rear chain

I moved to the 5 plate 850 clutch set up in my roadster, clutch rod end seal et all. Have no complaints with the system, but since switching over I've been using ATF in the primary and have noticed a red coating on my rear chain, I can only assume this is ATF seeping past the felt washer at the back of the chaincase. Now, there's no leaking of ATF other than that (none down the chaincase and onto the ground), and the chaicase level overall does not seem to be dropping in any significant quantity, so am I correct in assuming that:

a) the ATF (being a much lighter oil) is simply more prone to weeping past the felt washer due to centrifugal forces on the clutch rod?
b) I should be happy that I discovered a new method of auto lubing the chain?

I have always used ATF in the primary and have never had this happen. Is it possible that the felt seal is bad/improperly located or possible the chaincase is over full? I suppose the sheet-metal carrier for the felt seal could be so loose on the case that it is allowing fluid to seep by the carrier itself, not the felt seal. But that's all I can think of...

MexicoMike said:

I have always used ATF in the primary and have never had this happen. Is it possible that the felt seal is bad/improperly located or possible the chaincase is over full? I suppose the sheet-metal carrier for the felt seal could be so loose on the case that it is allowing fluid to seep by the carrier itself, not the felt seal. But that's all I can think of...

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It's certainly not overfilled, like I said, there's no leaking while sitting, just when run for awhile. But do you think my assessment is correct, felt washer? Is it a pain to get at? Should I leave for the winter? Thanks for the advice.

ludwig said:

acadian said:

.. a red coating on my rear chain..

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Rust , maybe ?
beats me how the ATF can get on the chain and not leak on the floor ..

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That's what I thought initially, but after a thorough cleaning and lubing of the chain, the stuff reappears after a highway jaunt... I have no idea what else it could be?

The felt washer is certainly a possibility and it makes sense - it would not drip while stationary because there is no oil up there but there would be some oil tossed around while operating which could seep out. The seal is not that difficult to deal with though it is a bit of a pain. Of course you will have to pull the chaincase completely because it can't be removed/replaced without the rear chaincase in your hands.

The new seal should be soaked in oil and pressed in a vice to make it thin enough to actually allow it to be forced into the carrier. It can be a little annoying but it's not that bad. The carrier itself should be able to slide back and forth on the chaincase but it should be quite tight when you try to move it. If it is loose, then I would assume ATF could work its way around it, causing a seep even though the felt seal is fine.

I'd check very carefully to determine if there is any OTHER possibility for this before I pulled the case.

I recently used some engine oil - forgot the brand - that was a red as ATF. One reason I didn't like it and quit using it was BECAUSE it looked like ATF and I like being able to immediately tell what's leaking (right now NOTHING! ) by the color. So if you are using engine oil of that color, it's possible it's not ATF.

But another point that was made is a good one - is it possible it is rust within the chain that, in combination with whatever chain lube you are using, is producing a reddish oil? (of course that assumes a standard, non-Oring chain).

It'll be interesting to hear what it finally turns out to be...

What kind of gearbox oil are you using? You may be seeing gear oil leaking out the main seal.

maylar said:

What kind of gearbox oil are you using? You may be seeing gear oil leaking out the main seal.

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Standard 4 speed gearbox, it's not gear oil, definitely a reddish tone, only appeared when I switched to ATF

I've run ATF in 2 Combats w/o any mess, BUT ONLY after it either leaked out while running to seek its natural level or I just fill so some chain flop would splash in bottom layer not quite touching chain, or barely when at rest.
Felt seal may be where its leaving to seek its own level, but after that not much at all. Its possible its leaking out at front case gasket and getting blown to chain and not drip off case when stopped.

hobot