Tranny output seal

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airway
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Joined: Fri Feb 07, 2014 8:10 am

Tranny output seal

Post by airway » Fri Sep 29, 2017 8:45 pm

Hello y'all. The bike is a '91 GS. The output shaft seal was obviously leaking as I was getting gearbox oil collecting in the lower swingarm boot.I got the cycleworks tool for pulling the flange, and it worked fine, but after reassembling everything, the flange is kind of hard to turn by hand, and notching a little bit in 4 spots per revolution. Everything I have ever read says that the flange should turn freely with no drag or notchiness, so I am wondering what I might have done wrong. When I disassembled it, I was kind of surprised at the ease of removal of the flange nut. Did not seem to be anywhere near 180 ft lb of torque on that nut. When I reinstalled everything, I cranked it down to around 180 ft lb. Do you think I should back the nut off again a bit and try again? Any and all advice/ideas appreciated. Thanks!

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ME 109
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Re: Tranny output seal

Post by ME 109 » Fri Sep 29, 2017 9:20 pm

I'd pull the flange again and make sure the output shaft spins freely without the flange. Torque is 163 lb. in my bmw manual.
Torquing that nut should make no difference to the free spinning output shaft.
Is the seal seated? Maybe the flange is contacting the seal?
Lord of the Bings

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airway
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Joined: Fri Feb 07, 2014 8:10 am

Re: Tranny output seal

Post by airway » Fri Sep 29, 2017 10:02 pm

Hmmm, I will check that. I drove the seal in till it felt like it was bottomed out, and it looks flush. I'll pull the flange and check that again Thanks much.

Wobbly
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Re: Tranny output seal

Post by Wobbly » Sat Sep 30, 2017 5:29 pm

Did you apply lube to the "contact surface" of the seal ?
After 20 years as a professional bike mechanic and 30 years as an engineer I know just enough to be dangerous !

airway
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Joined: Fri Feb 07, 2014 8:10 am

Re: Tranny output seal

Post by airway » Sun Oct 01, 2017 9:15 pm

Yes, I did lube that inner ring. I backed the nut off, got a brand new torque wrench, and set it to 163 lb. Much better now. I think maybe my old wrench is off.I know ME said that shouldn't make a difference, but it did. Think I'm OK now? Seems to spin free
now, a tiny bit stiff,but no notching, not totally freewheeling, though,I mean not like a roulette wheel, but easy to turn by hand . Thanks for you fellows' help. I appreciate it.

airway
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Joined: Fri Feb 07, 2014 8:10 am

Re: Tranny output seal

Post by airway » Tue Oct 10, 2017 7:21 pm

Well, I thought all was good by having put the new seal in and all. Rode about 150 miles this weekend. Decided I might ought to check to make sure it was ok. loosened the rear boot, and danged if about 3 tablespoons of gear oil poured out. So I am back to square one. I can't imagine what it can be. I have checked and re-checked that transmission vent/ground bolt, looked through it, blown through it. It is clear. I know some say that synthetic gear oil can weep past the seal, but I have been using synthetic in the gearbox for years with no issues. Any ideas?

Rob
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Re: Tranny output seal

Post by Rob » Tue Oct 10, 2017 10:12 pm

All I have to add (I have never replaced one of these seals in my life) is I remember hearing that this gearbox output seal is installed "backwards" of what logic might imply.

I suppose that means that the seal lip goes toward the inside of the gearbox?
Rob V

Rob
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Re: Tranny output seal

Post by Rob » Tue Oct 10, 2017 10:16 pm

Nothing to do with your issue. Your name reminded me of this old store chain:

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Also something to do with helping choking victims... ;)
Rob V

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ME 109
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Re: Tranny output seal

Post by ME 109 » Wed Oct 11, 2017 5:35 am

You might be right there, Rob. Opposite direction of the out put seal is to do with paralever models iirc. Spring facing out. Anyone?


There is also blocking of the notch above the seal with silicon. This might be causing a leak on this particular model. With the seal removed, there is a triangular notch at the top of the tranny cover plate where the seal runs.
Later models (which?) require this notch to be closed with silicon.
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airway
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Re: Tranny output seal

Post by airway » Wed Oct 11, 2017 8:12 am

It's a new type seal without spring, and even marked "inside" on one side for dummies like me. Also read about that v notch before I installed it, and it had been sealed before, I added a little more sealant to it just in case. I'm starting to wonder about that little bolt with the hole in it again. It sure doesn't look clogged, I mean, you can even blow through it. A few months ago, though, after I knew the seal was leaking, I removed the trans. oil filler plug to check the level, just in case I needed to add oil. The bike was still warm, and when the filler plug was removed, it kind of blew off with a "poof" and spewed a little oil-like there was air pressure behind it. Thanks

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