Drive shaft damper slipped

[85343]

I have a 95 R1100RSL with 90,000 miles. I pulled it apart to lube the input shaft splines. (Replaced at 69,000) The Krytox grease was still there and the splines had no visible wear. However the drive shaft had issues. When I assembled the drivetrain at 69k I marked the drive shaft with paint for alignment purposes. The marks were not aligned when I took it apart recently. The shaft spun about 45 degrees at the rubber vibration damper. I also have a hint of play in the rear u-joint. I took the drive shaft to Max BMW for a professional opinion. The service manager had the techs check the shaft. They said the drive shaft was OK. I would think that if it wasn't OK they would say so and sell me a new shaft. I put the bike together but I still feel a little uneasy about the shaft. I would have replaced it if it didn't cost $500. Has anybody had an issue like this with the drive shaft? I'm wondering how often I should check the drive shaft now.

Kurt

[PGlaves]

This one distinctly puzzles me. That shaft has a large diameter outer tube and a smaller diameter inner tail piece, both bonded to a rubber cylinder. I have always thought that if the bonding (glue) broke loose inside the outer shaft or outside the inner shaft that it would then continue to slip due to the lack of bonding.

I suppose that the rubber could be so compressed that it could hold by friction alone - I have never taken one apart to see - but I certainly never thought this was the case.

However - if it absolutely for sure changed alignment and doesn't slip - then I don't know what to think.

[flash412]

I'm wondering how often I should check the drive shaft now. I'll say every 90,000 miles, unless it start slipping before then.

[Morbius]

Interesting situation! I know that drag racers have noted that the rear half axles on their drag cars (and not just the big ones) will twist due to the torque applied by racing. Since drag machines only run in one direction, there is no significant torque applied in reverse. Over a couple of seasons the axles can be twisted a full rotation. Stand them up in the corner of the shop and in a couple of years they will have "relaxed" back almost straight.

Maybe the same is happening with the rubber sleeve?

I never liked the situation myself. The bond can break and where are you? Usually a gazillion miles from parts.

I've thought about making an articulated all-metal drive shaft for my R11S. Outer tube, inner tube, delrin or HDPE spacers between these and a middle tube. The middle tube is slit lengthwise full length at least 4 ways, so the middle tube essentially becomes a linear spring. Weld the middle tube to the inner tube at one end, to the outer tube at the other end. The inner and outer tubes could also be slit to match. Get rid of the rubber entirely.

[85343]

The shaft definitely spun. The service manager said the tech told him the rubber is a viscous coupling to allow movement. I'm not sure what to think either. It doesn't look like a viscous coupling. But glass is a viscous fluid, maybe the tech is correct. I had been running the bike very hard from standing starts on a remote road while adjusting a Techlusion. I also did a dyno drag during Laconia bike week, that was probably what did it. (91.2 hp) I had visions of destroying the new clutch I had just installed. The clutch is still fine. I wonder if the movement is a common occurrance. The only reason I knew was the paint marks I used for installing the shaft. How many people mark the shaft during installation?

[saab93driver]

It would be very odd for a rubber coupling in the driveshaft to have that much torsional set (permanent deformation). a few degrees maybe even 8-9 deg if it was a soft rubber compound wouldn't be unheard of after many running hours at high temps but not 45 degrees. The rubber would tear first.

It could be that it is not bonded on the OD but a press fit or clamped and it has slipped but if it has slipped some damage may have been done. There are some drive couplings that are designed to do that but I doubt the shaft is designed in this way.

If you are sure that it has changed, I'd replace it.

But I wouldn't get rid of the rubber without more facts. It is likely there as a cushion but also likely it is there to dampen torsional vibration excitations from the u-joints and to lower the torsional natural frequency. By going more rigid you may raise the natural frequency such that you wind up with more problems with splines or the final drive or the gearbox that will take some time to show up but could be more expensive in the long run. It should have been designed with this in mind as well.

[mrich12000]

I have a 95 R1100RSL with 90,000 miles. I pulled it apart to lube the input shaft splines. (Replaced at 69,000) The Krytox grease was still there and the splines had no visible wear. However the drive shaft had issues. When I assembled the drivetrain at 69k I marked the drive shaft with paint for alignment purposes. The marks were not aligned when I took it apart recently. The shaft spun about 45 degrees at the rubber vibration damper. I also have a hint of play in the rear u-joint. I took the drive shaft to Max BMW for a professional opinion. The service manager had the techs check the shaft. They said the drive shaft was OK. I would think that if it wasn't OK they would say so and sell me a new shaft. I put the bike together but I still feel a little uneasy about the shaft. I would have replaced it if it didn't cost $500. Has anybody had an issue like this with the drive shaft? I'm wondering how often I should check the drive shaft now.

Kurt

:wave Looks like the shaft has spun.
Juast like an old type rubber mounted propeller on an Evenrule outboard.
you just may be stranded with a spinning shaft. time to replace.. JUst a thought; Mike Richard .:banghead :banghead

[j-budimlya]

From what I know of rubber to metal adhesion...if it spins...it is no longer bonded...and it spins some more....

If, however, it seems to work fine....then it does not spin....can't imagine it both ways....

It has to handle quite a bit of torque....so, some kind of "iffy" sort of slipping can't happen.....it either slips alot or it doesn't ....