R1100 clutch slips at higher RPM

[SmokinRZ]

Bike has 53K miles and I took it apart to check the splines and everything else that goes with the job. The clutch disk measured 4.6mm and I had a used but clean BMW clutch pack from a parts bike that measured 5.5mm and was dated 2014. I cleaned the pressure plates with brake clean. The cable and arm have the specified free play. The clutch works fine and I rode it about 100 miles, then today I gave it a handful of throttle on the highway and it slips. Yeah I know, used parts, but it looked almost new with no bluing and measured out better than what I had and that didn't ever slip. The rear main seal looked fine also. I used guard dog on the splines but not too much. I'm stumped. This is on a 98 R1100GS.

Edited April 3, 2017 by SmokinRZ

[Jim Moore]

Unfortunately you know the answer. It's "gotta go back in and see what's up." Good luck.

 

As a note, most clutches last longer than 53K, but maybe it was abused in its prior life. Cool bike, btw.

[Redman]

My experince with clutchs (although not dry- single plate clutches) is that measuring the thickness of friction material is only one factor.

 

Feeling the texture and stiffness of the materail is a more imprtant factor. ALthough you say the replacement clutch pack is relativly new (2014) so I would not have suspected a problem that way.

 

 

[dirtrider]

Bike has 53K miles and I took it apart to check the splines and everything else that goes with the job. The clutch disk measured 4.6mm and I had a used but clean BMW clutch pack from a parts bike that measured 5.5mm and was dated 2014. I cleaned the pressure plates with brake clean. The cable and arm have the specified free play. The clutch works fine and I rode it about 100 miles, then today I gave it a handful of throttle on the highway and it slips. Yeah I know, used parts, but it looked almost new with no bluing and measured out better than what I had and that didn't ever slip. The rear main seal looked fine also. I used guard dog on the splines but not too much. I'm stumped. This is on a 98 R1100GS.

 

Morning SmokinRZ

 

What BMW (model & year) did that used clutch come out of?

[SmokinRZ]

Good morning DR, It came from a 97 R1100RT.

[dirtrider]

Good morning DR, It came from a 97 R1100RT.

 

Afternoon SmokinRZ

 

I'm not sure it makes any difference but there were some clutch pack changes on the 1100 around December of 1997. (they do appear to use the same flywheel though)

[Doctare]

I had that issue years ago and when I replaced the clutch again I used a GS spring rather than the RT spring. haven't had that issue in the 3+ years since.

[avu3]

I had this problem on a new-to-me bike and found the cable was out of adjustment. Adjusting the cable to the spec in the service manual resolved the issue.

 

Scott

[SmokinRZ]

Unfortunately the clutch cable and arm are adjusted properly with plenty of slack. It looks like the RT and GS spring plate had the same part number. I did notice a different listing for friction plates prior to 12/97 but I replaced the whole pack so I'm not sure if that has something to do with my issue.

[dirtrider]

Unfortunately the clutch cable and arm are adjusted properly with plenty of slack. It looks like the RT and GS spring plate had the same part number. I did notice a different listing for friction plates prior to 12/97 but I replaced the whole pack so I'm not sure if that has something to do with my issue.

 

Evening SmokinRZ

 

I went through some of my old BMW 1100 era service bulletins & only found one that COULD apply to your situation (there might be others but the old bulletins were not in electronic from so I basically have a shop drawer full of bulletins without any subject indexing)

 

In any case ,if you somehow ended up with a post 12/97 pressure plate made for the thicker clutch disk but used a thinner pre 12/97 thinner disk I suppose that there might not be enough clamping force (basically a wild guess on my part) --

 

Added: The thicker clutch disk is .3mm thicker

 

Sorry I can't post the entire bulletin as it is BMW protected but here is the part that has the meat & potatoes--

 

 

All R 850/R 1100 and K 1200 RS models produced from December 1997

have received a new clutch disc, manufactured by VALEO, and a

new pressure plate (see applicable part numbers below).

Earlier production for both series can be fitted with the new parts.

However, due to changes in specifications (a thicker pressure

plate, a thinner clutch disc), the new VALEO clutch disc is not

compatible with the old pressure plate. In this application, the

new clutch disc and pressure plate must be replaced as a

pair.

Series

Production:

R 850/R1100 models: Starting with December 1997 production.

Edited April 3, 2017 by dirtrider

[SmokinRZ]

Thank you DR. The pressure plates were Sachs and the disk was BMW but made in a country other than Germany that escaped me at the moment. I suppose it all come back apart now. I'm thinking about getting a new Siebenrock friction plate and the 1150 spring plate. I have the Siebenrock in my 99 GS and it is a little more abrupt on engaging but measures something like 6.5mm vs 5.5mm for the BMW disk and is cheaper. Of course I will carefully examine the pressure plates but they looked brand new when I put them in. So confused.

[SmokinRZ]

Okay, it finally cooled down here in Texas and I pulled it all back apart. It was my fault as a speck of grease flung onto the pressure plate, It only took one small speck to make it slip at the upper RPM. I watched the CH videos and tried to mimic his application with a toothbrush. However, I was using Guard Dog Molly which seems to have a little more grease than the Staburags that CH was using. Just like when you lightly grease an axle for the wheel and then drive it home, the close tolerances cause the grease build up on the end of the pressure plate and it flung off with RPM which brings up the question of using Guard Dog Molly for this application. I used it on my 99 GS when I replaced the transmission with no issue. I have some Honda Molly 60 that seems less likely to fling and then someone here also mentioned Sachs spline lube. Regardless of what I use, it will be sparingly. I have seen aftermarket Sachs friction disks, but I have had had good luck with the Siebenrock in my 99 GS so I think that is what I will go with that. The pressure plates look brand new so those didn't get ruined.

 

I also noticed a leaking output shaft seal on the transmission that left a teaspoon of oil. I will try to drill small holes and use wood screws to get that out and replace it, and no more synthetic transmission oil even if it shifts better. So a new output shaft seal and Siebenrock friction disk and I will be back on the road.

.

[Mike279]

The moly paste can be easily overdone. Using a tooth brush gets the paste in the splines nicely. The effect you are looking for is coated but almost wiped clean off. I doubt a speck of moly will make a clutch plate slip. Remember you have two sides and plenty of surface area on a clutch disc. Looking at the Flywheel and pressure plate should be followed by using a straight edge and feeler gauges to make sure they are flat. If they are not flat only part of the clutch disc will contact them and the reduced contact area will make the clutch plate slip. Then consider replacing the spring as they can weaken over time and not apply enough pressure. I usually find used parts need some service to be used over and function correctly. If there is any doubt new parts are not that expensive compared to the time lost taking the bike apart twice. Mike

[SmokinRZ]

The pressure plates are perfectly flat with a straight edge, unlike my original 54K mile plates, and the machine marks are still visible. I cleaned up the original disk with brake clean and it would probably be ok to use but I'm not doing this a third time. Output shaft seal is on order and now i'm wondering if I should replace the input shaft seal at PM? I didn't order one so chances are I will leave it alone and stick with non-synthetic gear oil. Does anyone have experience with the TRW Lucas ceramic disk? I am leaning towards the Sachs aftermarket disk, it should be the same as BMW part.