[aztechmaster]

OK so I am finishing up my clutch job, new disc, drilled weep hole, and replaced the transmission seals.....and YES the output seal leaks! Not while running mind you but after shutdown. I still have the swingarm off just to make sure all was well and it isn't. I did fill the trans up with synthetic 75/90. So tomorrow I will be looking for a different seal than OEM. You can actually SEE how poorly the seal fits around the shaft. Should I use a different fluid for the trans??

 

[K100Dennis]

Please don't get offended, but I offer the following questions in the hope of helping to understand your problem - 1. Are you absolutely certain the seal is the correct shaft size ? OEM part or not, mistakes can and do get made in supply. 2. Is the seal 100% undamaged as a result of the install process ? Deformation of the seal body will cause leakage. 3. Are you certain the seal is installed squarely and to the correct depth in the houising ?. 4. Is it possible the seal spring has become dislodged during installation ? Only removal and examination will confirm this. Recommendations - check the shaft surface to make sure there are no marks from the removal process. Push some clean cloth into the space behind the seal and take some 1200 grit wet 'n dry paper and lightly linish the seal running area. Do this using CRC or WD 40 or simiar as a lubricant. Caution, do not use paper any coarser than 1200 and do not allow the grit into the gearbox as it contains carborundum from the paper, the natural enemy of the bearing. Reinstall the new seal with lubricant on the shaft and in between the seal lip and outer dust lip. Do not use impact which can cause seal distortion. Finally, check the gearbox breather is clear. Hope this helps.

 

[aztechmaster]

Dennis- no offense taken, I am an ASE -L1 master auto tech.Yes I did everything you mentioned, including verifying the seal with Sturgis BMW where I bought all the parts. I even used a seal porotector from my tans kit to cover the splines while installing along with trans gel. The seal I removed was NOT leaking, but the rear mainshaft was, along with a very poorly installed and damaged rear main seal (the oring was already a viton one). I bought the bike last year and found service records from a dealership in Wisconson, which I called, who had done the clutch/seal three years ago. I plan on taking pics of the seal showing the lousy fit, and will gladly post them here. Tomorrow I plan on visiting a large local bearing/seal store with fingers crossed.
I had a rear main seal failure on my 2004 K1200RS four years ago....with 3200 miles.....nine weeks out of warranty. Of course BMW denied any warranty consideration, so I did that myself, with zero issues. This is the fourth K bike I have replaced clutchs/seals on. Bad batch of seals? Poor rubber? Just very glad I was so very picky about it, could have (eventually) toasted the trans.

 

[LittleJoe]

You possibly know this but just a fyi . Always fill the back side of seal(where spring sits) with clean grease. This will prevent the posibility of the spring jumping out of place during seal installation. The shock of tapping seal in can sometimes cause this spring to jump off.

 

[aztechmaster]

Yes that was what the trans gel was for.

 

[clayton]

I have had the same problem when my clutch and seals were replaced. The shop replaced two trans output shaft seals and each time the seal was installed correctly, and showed no signs of damage upon installation. The third and last seal installed the shop installed, put a thin layer of silicone in the small groves that are in the seal surface then installed. It has been a couple thousand miles now and no leaks. I have spoke to several dealer service departments and this seems to be the correct fix.

 

[ErnieA]

I have had the same problem when my clutch and seals were replaced. The shop replaced two trans output shaft seals and each time the seal was installed correctly, and showed no signs of damage upon installation. The third and last seal installed the shop installed, put a thin layer of silicone in the small groves that are in the seal surface then installed. It has been a couple thousand miles now and no leaks. I have spoke to several dealer service departments and this seems to be the correct fix.

I was going to make this same suggestion! Good call Clayton. Use RTV (very thinly smeared on the seal outer diameter) and guide the seal on over the shaft. The seal is not a tight fit into the case which surprises me. The last time my transmission was worked on at a BMW shop the mechanic used one hellabunch of RTV (much overkill) but it was sealed tight.

 

[rattler50]

I use a lot of RTV silicone in transmission work but I use it sparingly. Too much and it's just wasted and looks like some guy at a wrecking yard did it......................... :histerica

 

[jrh2020]

I'm confused...

... The third and last seal installed the shop installed, put a thin layer of silicone in the small groves that are in the seal surface then installed. ...QUOTE]

Originally Posted by ErnieA
.... Use RTV (very thinly smeared on the seal outer diameter) and guide the seal on over the shaft. The seal is not a tight fit into the case which surprises me. The last time my transmission was worked on at a BMW shop the mechanic used one hellabunch of RTV (much overkill) but it was sealed tight.

Clayton's post sounds like putting silicone on the internal diameter seal surface (rotating surface) and ErnieA's post sounds like silicone around the outside diameter which I assume is a press fit seal into the transmission case.

The original thread would seem to indicate gaps between the seal surface and the rotating shaft.

Given that the silicone is a much softer material than the seal lip, would be surprised that it would hold up as long as a well fitting seal on the ID, on the press fit side it would seem to be a good precautionary measure.

 

[K100Dennis]

Yes, I'm confused too. This seal leakage phenomenon cannot be too hard to solve, surely. A standard type lip seal with an external wiper is being installed into an aluminium case with a steel shaft. If the seal has a metal outer case design then the case must be sealed to the housing using Permatex, Hylomar, Loctite 515 or similar. If the seal has a Nitrile or Viton cover extended over the steel body then the seal is normally installed into the housing using a light film of grease to assist. If the sealing lip must pass across a circlip groove in the shaft then the groove is normally covered with some PVC tape which needs to be removed after the seal is in position, this prevents damage to the seal lip and also stops the hat spring flicking off. If the shaft is grooved from a previous seal running there, then carefully measure and calculate a new seal position either slightly inboard or outboard of the original placement.

 

[aztechmaster]

OK solved it!.. :dance: After some thought, I simply found a correct sized seal in a local bearing/seal warehouse, 25X40X7. I then removed the garter spring, unscrewed it, then snipped about 1mm from its length. I screwed it back together, slipped it back into the groove in the seal, and carefully installed it. MUCH tighter fit, and NO leaks! Check out the pictures, you can see the smaller garter spring!

 

[aztechmaster]

..............and of course the best part of all....

 

[ErnieA]

I'm confused...



Clayton's post sounds like putting silicone on the internal diameter seal surface (rotating surface) and ErnieA's post sounds like silicone around the outside diameter which I assume is a press fit seal into the transmission case.

The original thread would seem to indicate gaps between the seal surface and the rotating shaft.

Given that the silicone is a much softer material than the seal lip, would be surprised that it would hold up as long as a well fitting seal on the ID, on the press fit side it would seem to be a good precautionary measure.

The silicone is to be used on the outer diameter of the seal where it presses into the transmission case.

 

[jzeiler]

OK solved it!.. :dance: After some thought, I simply found a correct sized seal in a local bearing/seal warehouse, 25X40X7. I then removed the garter spring, unscrewed it, then snipped about 1mm from its length. I screwed it back together, slipped it back into the groove in the seal, and carefully installed it. MUCH tighter fit, and NO leaks! Check out the pictures, you can see the smaller garter spring!

I think Dan Martin tried a ...x7 and it didn't work for him and went back to a ....x6 with success. Looks like the real secret is the ....x7 with the tighter spring. That's what I'll use the next time. Thanks for posting. We had another member here that went through four seals and still had a leak. Was begining to think there was a bad production run.

 

[aztechmaster]

I used an SKF seal, P#692313. I got two for less than 8 bucks! I plan on visiting the dealer this weekend, returning my old seal and offering my solution.

 

[jzeiler]

Thanks for the info. I have another tranny rebuild coming up and I did not fair well on this seal the last time but it did hold for about 3 months.

 

[saddleman]

Only time will tell if the increased tension will wear the seal out early.

 

[K100Dennis]

Can someone do a garter spring length & tension comparison maybe ? Compare an OEM seal spring with the aftermarket one(s), maybe there are distinct differences. This is not normally an issue in industry, and this application just isn't any different, so it has me puzzled I must admit.

 

[jzeiler]

Check again Dennis - he shortened the stock spring in the ...x7 seal by cutting 1mm out of it.

 

[K100Dennis]

John, 1mm off the circumference is 0.3 mm off the diameter. I would think that hardly enough to increase garter spring tension by any significant amount, and surely can't be the difference between sealing and leaking ??
I used to shorten the seal springs in my Aprilia forks to make them seal for longer, but I cut about 5 mm off those springs and then filled the seal cavity with RTV silicone and let it cure completely before installing the seals. It worked well, but eventually still leaked. It came doen in the end to needing to linish the fork legs. Different application I know, but the surface was the problem in that instance, not the seals.