Transmission Output Seal Leak or Torn Swingarm Boot? Both?

[Niemand]

Soon after purchasing my bike I discovered it lacked the ability to keep all the juice in the transmission.  It might have simply been overfilled, but the clutch control arm boot was suspect, so I replaced it last week.  The one that came out looked relatively intact, so I have begun to wonder if I actually have a leak where the swing arm and  transmission meet.

Would there be a leak simply due to a torn or improperly installed boot between the transmission and swing arm, or would that indicate the output shaft seal on the rear of the transmission is toast too?  I am still working out a few other issues, so I haven't had a chance to test my current setup after the clutch boot replacement, but I wanted to know ahead of time what to expect if it still decides to dump gear oil on my exhaust as before.  Once I get the new fork seals in, de-lube the front rotors and replace the cracked right peg plate I will be putting it back together to take it out for a test run to see if it still leaks.  (or perhaps not...just remembered I recently discovered the shock is leaking too.  I'm in denial, as that is going to take some time to resolve.)

I still need to replace the clutch nut o-ring in the near future, so if I have to take the swing arm off anyway, I will just take a shot at the whole thing at once.  After 18 years and a good bit of neglect, I'm pretty sure it is due for a spline lube too.  It only has about 29k miles, so I'd like to get up to speed with the service intervals before finally getting it back on the road. (finally...finally...going insane.)

[frankenduck]

Could be the pinion seal on the back of the trans.  Pull the final drive off and look for a slug track in the swing arm.

[Scott_]

Is the oil running down onto the top of the exhaust, or is it only on the bottom of it.

If you are getting gear oil on the top of the exhaust, I'd suspect it being overfilled and coming out the top vent that is on the left side of the trans. Same side as the exhaust.

[Niemand]

Could be the pinion seal on the back of the trans.  Pull the final drive off and look for a slug track in the swing arm.

Will do.  Thanks.

Is the oil running down onto the top of the exhaust, or is it only on the bottom of it.

It seemed to be primarily coming from the right side.  It was all over the top of the exhaust after the headers join (collector box?) just below the clutch boot and running down beneath that area as well, which is why I figured that was torn.  It could be fine now that I have replaced that and refilled it properly, but I just wanted to get an idea of what I might be dealing with if the leak persists from that direction.  Combined with what could just be a slow leak from the clutch nut o-ring, it looked pretty bad.  I hope to check it out soon now that it is cleaned up and I can trace leaks easier.

[frankenduck]

Could be the pinion seal on the back of the trans.  Pull the final drive off and look for a slug track in the swing arm.

Will do.  Thanks.

Is the oil running down onto the top of the exhaust, or is it only on the bottom of it.

It seemed to be primarily coming from the right side.  It was all over the top of the exhaust after the headers join (collector box?) just below the clutch boot and running down beneath that area as well, which is why I figured that was torn.  It could be fine now that I have replaced that and refilled it properly, but I just wanted to get an idea of what I might be dealing with if the leak persists from that direction.  Combined with what could just be a slow leak from the clutch nut o-ring, it looked pretty bad.  I hope to check it out soon now that it is cleaned up and I can trace leaks easier.

I don't think overfilling would cause that to happen.  When I bought my K1100RS, the PO had recently had the trans oil changed at Ventura BMW by some manual-reading monkey who refilled it to the bottom of the fill hole threads.  I rode it (pretty hard) from Malibu to SF and nothing came out.  I discovered the over-filled trans in SF at a buddy's place with a lift where I stopped to give the bike a going over.  (They also installed a new front tire backwards so that it destroyed itself within 1,000 miles. Quality shop I tell ya. :loopy:)

[Niemand]

So I have found no other major leaks so far, but may have discovered the original issue that I thought was a torn boot.  After using the clutch lever a few times, I can see gear oil weeping from the clutch arm adjusting screw, right through the lock nut.  It must have been pretty bad originally given the amount of leaking when I bought it, but now it is still too much for my liking as it is quite noticeable when watching for it and still drips right on the exhaust.

Prior to finding this I did a clutch adjustment, and set the screw just where I started to feel resistance.  Should I crank it in just a bit more perhaps, or is this indicative of something further in needing to be looked at?  The boot seemed to seat fine on the screw during installation as far as I could tell, and it does not leak at all until the clutch lever is pulled a few times.

If it matters, this is happening despite the fact that the bike has not been run since the boot replacement a couple of months ago.  I've had the front end off doing some other work and had to get a new right peg plate. I just caught this during reassembly yesterday.  I've yet to read of anyone else having a leak there, so advice would be appreciated.

[Rick G]

I had asimilar problem some time ago with the K100. the clutch cable was an aftermarket and not quite the right length so the adjuster screw was screwed in too far making the arm sit too far back and as a result the arm didnt seal against the rubber boot so the thing leaked.The clutch arm pushes against the rubber boot around the steel insert in the back of the boot and that was not happening.
It could be adjusted out but it left nothing to adjust for normal stretch at a later time. I had to fit a OEM cable and all was OK.

[frankenduck]

Make sure the ring of the boot is well-seated on the clutch arm.