BMW K bikes (Bricks)

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sid_knee

sid_knee
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Hi, I bought a 94 K1100 that had been sitting around for a while. All the rubber seals died as soon as I started riding it. Fine. I'm used to them going and replace them.

July 2020 The RMS went, taking a friction plate out with it. Cool. Replaced them both as Mr Clymer says to. The stop disc crumbled as I took the clutch housing off, but given that I was in rented workshop space I elected not to replace the stop disc and just press on regardless, the wait time and cost for a replacement 1mm magic washer being 9 weeks and $100.

3 weeks later there is a decent stream of oil out the weep hole. Mistake :/ I bite the bullet and order a stop disc from Munich. Given how annoying having to rip a K bike in half is I replace the main seal here again in case it was a dud seal (It was one of the older type seals with the little spring). This time I also made sure to make the RMS sit either deeper or prouder (can't remember which) in case there was scoring on the output shaft even though I couldn't see or feel any. Everything back together and it's OK for 6 months and a 1,200Km tour + daily commuting, but then it starts slipping on acceleration in 4th/5th.

I manage to baby it for another 1000Kms to a family farm where I have access to a decent workshop and have ripped it in half again only to find engine oil on the engine side of the clutch. I was thinking it might have been a clutch spring or the friction plates at fault (they are a little worn but in spec) so I found a 2nd hand clutch on eBay and intended to install it, but now I know it's another leak I'm not sure what I should do. I replaced all the bolts you should replace every time. And the O ring is new every time. Torque specs all followed each time. The leak is always from behind the clutch housing, never through the Oring.

I don't have precision measuring tools, so I have to wait until tomorrow to get a machinist in town to measure for me. I have compared the two clutch housings and pressure plates visually and by touch. The replacement set looks older in construction but less worn on the pressure plates. Both of the surfaces that would rub on the lip of the RMS feel similar and the rusty calipers I had to hand measured the same on both.

One side issue is that I have no idea what orientation the 2nd hand clutch assy should be in as whoever salvaged them didn't mark them so if anyone has any advice on that I'll take it.

I bought the expensive "touring" friction plate because I just can't face ripping apart this bike again and the leak is quite minor. I'm going to order another main seal, but
would replacing the clutch assembly potentially solve these leaks?
Should I use the stop disc on the replacement clutch?(I'll measure this as well to be sure)
Am I missing something obvious?
This is the RMS I have on now that is leaking, the product description now I look at it doesn't mention K1100LTs (will call tomorrow about that) could that be a thing? I can't imagine there's that much difference with the 100 Vs 1100 in this area.

Thanks for reading the epic!

Pics:
https://ibb.co/277Gg7F
https://ibb.co/xFH8xrC
https://ibb.co/ySH9fXX
https://ibb.co/LzYtx1v
https://ibb.co/vmBjbqn


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K1100LT (94)
    

Waz

Waz
Life time member
Life time member
Tom had a similar problem, he was supplied with the wrong size O ring.


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1988 K100 RS
1999 K1200 RS
1987 K100RS DJP sidecar
    

3Back to top Go down   Rear main seal replaced twice last Year, Leaking a 3rd time. What am I doing wrong? Empty Rear main seal Sun Oct 10, 2021 2:01 am

daveyson

daveyson
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I'm not familiar with the k1100, but it looks very much like the k100, so this might be useful.

There is only a tiny amount of clearance between the clutch basket and the seal (and engine casing) Because you didn't use the stop disc, the clutch basket was possibly in contact with the seal. From your photos I'll guess the seal turned a bit under the pressure and causing the damage to the clutch basket. I'm assuming your other replacement seals were also the older type, so not wider, so no need to be proud. It's to prevent the seal distorting, not the lip on the shaft issue. If you offset it with an original width seal, that might have caused the leak. 

I'd use the original clutch basket (the overall shaft length also needs to be exactly the same on both of them) The second time, if the seal was proud, it might have again been in contact, especially if you used the non original clutch basket. Make sure there is clearance next time. 

If you still have bits of the original stop disc, measure its thickness. If not there is a thread describing how to find the stop disc clearance in the how to section called "how to understand the k100 engine output shaft" Again keep in mind that's relevant to a k100, don't know how relevant to yours that is,but I think it still applies. The disc needs to be a bit thicker than its clearance.

The k100 clutch I looked at had a yellow paint dot on the clutch basket, and two white paint lines on the other bits. If the paint marks are gone you might still see the patina left.



Last edited by daveyson on Sun Oct 10, 2021 2:52 am; edited 2 times in total


__________________________________________________
11/1985 bmw k100rt (late model)  Vin. 0090567
 ~120,000 km
    

sid_knee

sid_knee
active member
active member
I'll have a look at the clearance for the thrust washer. How do you measure that? feeler gauges through the holes in the clutch housing? I have never run this bike with a different clutch assy. I just have one here as an option to put in. The thrust washer I lost between 1st and 2nd main seal replacements so never measured. The downsides of using shared workshop space Sad

I'll drive back out now while it's light and find the old O ring I binned and measure it. The new one I have here is 27mmOD 19mmID, where the one on EME (only reference I could find with dimensions) is listed at ø 27/18mm. Also measure the output shaft. Anyone have a confident source for the correct clutch O ring dimensions? I took it off today and it felt as securely on like the other 3 I've done (also did my dads 89 K100 years back with no issues). I couldn't find a tom posting about wrong O ring sizes, but the new one and the one I just took out are from the same AU supplier...


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K1100LT (94)
    

5Back to top Go down   Rear main seal replaced twice last Year, Leaking a 3rd time. What am I doing wrong? Empty Rear main seal Sun Oct 10, 2021 3:00 am

daveyson

daveyson
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Life time member
If the seal is original width and you install it flush you should have clearance between the clutch housing and the seal, then you don't have to measure the stop disc clearance. You could recess it if there's enough clearance for the lip. 

I think you have the right O-rings, cause they're not leaking.

Am I right in guessing there was sometimes a bit of a rattle going on during the three weeks you rode around without the stop disc installed?


__________________________________________________
11/1985 bmw k100rt (late model)  Vin. 0090567
 ~120,000 km
    

Laitch

Laitch
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That seems to be a teflon seal. If it is, when installing a teflon seal its inner lip should be expanded so it doesn't deform by rubbing against the shaft during installation. Some use a plastic pill bottle for that purpose. I don't know what healthy people use but it's either spreading that lip by hand or other means.  Smile  The inner seal will contract and securely grip the shaft after installation. Also, it should not be oil-soaked before installation like the old-style seal with the perimeter spring. The Clymer manual I have doesn't seem to explain any of that where I looked. I wouldn't be omitting the stop disc either.


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1995 K75 81,000 miles
Rear main seal replaced twice last Year, Leaking a 3rd time. What am I doing wrong? Usa-lo10
    

RicK G

RicK G
admin
admin
If the thrust washer is not there it can cause the O-ring to leak because there is not enough pressure to make an oil tight seal.
I use viton seals because the nitrile seal will  harden with the heat. Viton seal is 80 x 50 x 8mm and goes in flush with the surface.


__________________________________________________
"Man sacrifices his health in order to make money.
Then he sacrifices money to recuperate his health.
And then he is so anxious about the future that he does not enjoy the present; the result being that he does not live in the present or the future; he lives as if he is never going to die, and then dies having never really lived."   Dalai Lama


Bikes 2004 K1200GT 1998 K1100 LT, 1993 K75 RT, 1996 K75RT, 1986 K75 GS, 1979 Z1300 Kawasaki
    

8Back to top Go down   Rear main seal replaced twice last Year, Leaking a 3rd time. What am I doing wrong? Empty Rear Seal type Sun Oct 10, 2021 5:23 pm

redrockmania

redrockmania
Silver member
Silver member
Further to RickG's post: There are significant maximum operating temperature capacities depending on the rubber compound type. Nitrile is safe up to 110C - Viton is safe up to 205C. While Viton is usually a red/brown colour, sometimes it comes in a different colour.

    

9Back to top Go down   Rear main seal replaced twice last Year, Leaking a 3rd time. What am I doing wrong? Empty Rear main seal Tue Oct 12, 2021 2:13 am

daveyson

daveyson
Life time member
Life time member
"The leak is always from behind the clutch housing, never through the O ring"

I don't get this bit, the O ring is behind clutch housing, unless you mean looking from the rear. I think I get the point from the other posts that a leak from the O ring would be more likely to contaminate the clutch than from the seal. 

Although the parts weren't marked when removed, there are three paint marks from the factory for the heavy points. They should be spaced 120 degrees apart. You can see one in your photo of the pressure plate. There will be another one on the outer side of the cover plate, and one on the inner side of the clutch housing.


__________________________________________________
11/1985 bmw k100rt (late model)  Vin. 0090567
 ~120,000 km
    

sid_knee

sid_knee
active member
active member
Thanks all. I've ordered a new RMS, I can't get at a viton one quick enough in my current rural setting, so I have to go for the same teflon again. This time pill bottle stretched. I remember last time I also had it in the freezer so it'd fit better, but I'm thinking now if it's that much of a princess with temperature maybe best not to.

I'm talking in reference to looking at it while doing this job. If your head is where the gearbox was, it goes Nut, compression ring, O-ring, (output shaft), clutch housing, stop disc, engine. There is never oil on the nut or dribbling down the concave side of the clutch housing. It always comes from between the engine and the convex side of the housing. This is perhaps further evidenced by staining on the outer edge of the friction disc as if loose oil had flicked up from the bottom of the gearbox/engine cases and a pristine inner section, where if oil was being flung around centrifugally you'd think it'd coat the whole surface of the disc.

Now I know where to look on the replacement clutch I can try find those markings. When I did before I couldn't tell if I was looking at a mark or a smudge or a ghost.


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K1100LT (94)
    

Arlina

Arlina
Moderator
Moderator
I'm missing something here.
In the engine is a retour hole for the engine oil where the RSM comes, RMS must not be pressed in over the hole, gotto measure where the hole is and how deep you can push the RMS just not to cover.
Takes me to the second one, is that hole open?


__________________________________________________
Rear main seal replaced twice last Year, Leaking a 3rd time. What am I doing wrong? Eu-log10  K1100RS/LT - R1200RT - R1100RS (RIP) - Cagiva SST 350 Ala Verde - K75LT project - K75 Schurgers - K75S
    

sid_knee

sid_knee
active member
active member
Aha. Very good question. I assume you mean this hole.

I think you are right. It seems I might have made a mistake and pushed the teflon RMS in too far. Not sure it's far enough in to be fully covering the hole, but in trying to figure out what you meant by return hole I found many pictures of the teflon seal in place and in none of the examples is it in as far as mine is. I must have confused it with the thinner Viton seal or maybe I'm just stupid and hit it too hard. It's been known to happen.

Also Red LTs are the best LTs (;


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K1100LT (94)
    

RicK G

RicK G
admin
admin
The teflon seal should be 10mm deep and sit level with the case. There is no need to use a pill bottle, you can't actually do that trick there as it is done on the front crank seal, tap the seal in gently until it is level with the case then put a film of oil on the lip of the seal before you push the clutch carrier through. The pill bottle trick is so the seal wont turn inside out when the front cover is seated on the engine block but here you are pushing the carrier through the seal so it cant do anything but expand to fit the shaft.
I use a piece of soft wood with a hole in the centre so the shaft goes through this way it is not as easy to damage the seal.
I usually put some oil on the seal and before you put it in run your finger round and round for a few minutes so as to gently stretch the seal lip and soften it a bit that way the shaft is easier to insert, the seal lip will contract back to the correct size in a few minutes.


__________________________________________________
"Man sacrifices his health in order to make money.
Then he sacrifices money to recuperate his health.
And then he is so anxious about the future that he does not enjoy the present; the result being that he does not live in the present or the future; he lives as if he is never going to die, and then dies having never really lived."   Dalai Lama


Bikes 2004 K1200GT 1998 K1100 LT, 1993 K75 RT, 1996 K75RT, 1986 K75 GS, 1979 Z1300 Kawasaki
    

sid_knee

sid_knee
active member
active member
I'm getting a bit confused. here, old mate has the same seal and has 3d printed a jig to keep it 0.5mm out of the casing with a BMW memo telling as much. But the teflon seal is not OEM and is 2mm(?) thicker than a BMW seal, so the BMW memo could very easily not apply because the aftermarket seal design might accommodate this 0.5mm difference in lip location. But nobody in that thread is saying "no wait! hammer it in a bit more so it's flush". Is that a USA vs rest of world thing? 100 Vs 1100?

Thing is, making it flush with the casing is how it is now. I can't help but feel that installing the RMS again in the exact same fashion is inviting more suffering.


__________________________________________________
K1100LT (94)
    

RicK G

RicK G
admin
admin
So the Teflon seal is 12mm deep?


__________________________________________________
"Man sacrifices his health in order to make money.
Then he sacrifices money to recuperate his health.
And then he is so anxious about the future that he does not enjoy the present; the result being that he does not live in the present or the future; he lives as if he is never going to die, and then dies having never really lived."   Dalai Lama


Bikes 2004 K1200GT 1998 K1100 LT, 1993 K75 RT, 1996 K75RT, 1986 K75 GS, 1979 Z1300 Kawasaki
    

sid_knee

sid_knee
active member
active member
I thought you said earlier viton was 8mm? Is viton not the OEM supplier/material? I did say I was confused (:


__________________________________________________
K1100LT (94)
    

Laitch

Laitch
Life time member
Life time member
Here's what's being sold by a BMW dealer in New England and New York, USA.

Rear main seal replaced twice last Year, Leaking a 3rd time. What am I doing wrong? Scree174


__________________________________________________
1995 K75 81,000 miles
Rear main seal replaced twice last Year, Leaking a 3rd time. What am I doing wrong? Usa-lo10
    

18Back to top Go down   Rear main seal replaced twice last Year, Leaking a 3rd time. What am I doing wrong? Empty Rear main seal Tue Oct 12, 2021 10:59 pm

daveyson

daveyson
Life time member
Life time member
The last photo in your first post, where the seal makes contact with the clutch housing, the clutch housing surface looks rough to me, especially on the left side.  Maybe it's just a reflection, dunno.


__________________________________________________
11/1985 bmw k100rt (late model)  Vin. 0090567
 ~120,000 km
    

RicK G

RicK G
admin
admin
@sid_knee wrote:I thought you said earlier viton was 8mm? Is viton not the OEM supplier/material? I did say I was confused (:
OEM was 80 x 50 x 10mm of nitrile which was updated about 10 years ago with a similar nitrile seal with a slightly different seal lip hence the 0.5mm left protruding and that was replaced by a Teflon seal of the same dimensions.
I found a Viton seal in OZ and have been using them since around 2011 as they are more likely to take the heat. The Teflon seal should also take the heat so is a good replacement.
I get the Viton seal from Statewide Bearings here in Queensland but I'm not sure where in Victoria or NSW you can get them.


__________________________________________________
"Man sacrifices his health in order to make money.
Then he sacrifices money to recuperate his health.
And then he is so anxious about the future that he does not enjoy the present; the result being that he does not live in the present or the future; he lives as if he is never going to die, and then dies having never really lived."   Dalai Lama


Bikes 2004 K1200GT 1998 K1100 LT, 1993 K75 RT, 1996 K75RT, 1986 K75 GS, 1979 Z1300 Kawasaki
    

sid_knee

sid_knee
active member
active member
Ah yes. There is a bit of crap stuck on there. It comes off with fingernails. I was planning on sanding it slightly to give it some tooth, but I'll get rid of that too.

I took some better shots and had a closer look. It appears the polished area where the seal rubs on the housing extends all the way off the edge of the surface. Leading me back to the maybe it needs to be 0.5mm proud of the case theory..?

this is the one from the leaky bike, there's two polished areas, but the rightmost one extends to the edge
this is the one from ebay, polished area far from the edge


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K1100LT (94)
    

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