Gearbox Shaft Seal Leak

[Ron from BC]

Very small leak (< 1 tspn) from the front end of the driveshaft gaiter. Several days riding since it was cleaned up and there's still nothing further coming out (for now).

I understand it should be impossible to overfill the trans as the oil will just ooze out the side filler plug but.....if there was a slight overfill a couple of weeks ago during a change would this surplus being sufficient to cause a 'temporary' leak out of the output shaft seal?

 

[MattW]

Very small leak (< 1 tspn) from the front end of the driveshaft gaiter. Several days riding since it was cleaned up and there's still nothing further coming out (for now).

I understand it should be impossible to overfill the trans as the oil will just ooze out the side filler plug but.....if there was a slight overfill a couple of weeks ago during a change would this surplus being sufficient to cause a 'temporary' leak out of the output shaft seal?

I don't think a slight overfill would cause a leak from the output shaft seal. However a blocked gearbox breather might - could be worth locating it and checking?...

That said, are you sure it's coming from the gearbox and not the final drive? It's not unknown for the final drive input seal to pass a little oil and those who know say it's nothing to worry about.

I had a gearbox output shaft seal fail (twice ) and it filled the gaiter with about half a pint of oil in 100 miles

 

[Ron from BC]

...hrmmm gearbox breather? Well let me see if I can find it and then I'll have a look thanks!

That small amount of oil it leaked was jet black too...whereas the 80-90 I just put in is still amber and clear. I have read about the other cause being the input seal for the FD. I was going to take the gaiter strap off the front and have a look up the housing for any trail but realized I didn't a zap tie that was long enough to put back on so I'll pick one up first (that or a SS strap that others have mentioned)