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How much slop is normal in a cushioned drive shaft? I know there should obviously be none in the u-joint. What I am wondering about is the movement in the cush part of the shaft. Hope this makes sense. What I am trying to determine is if the spring in my shaft is shot. I can rotate the shaft about 15 or 20 degrees before the shaft starts to engage one of the ramps.

Thanks in advance,

Ken

kreece wrote:How much slop is normal in a cushioned drive shaft? I know there should obviously be none in the u-joint. What I am wondering about is the movement in the cush part of the shaft. Hope this makes sense. What I am trying to determine is if the spring in my shaft is shot. I can rotate the shaft about 15 or 20 degrees before the shaft starts to engage one of the ramps.

Thanks in advance,

Ken

That's pretty normal from my experience with solid drives. Cush drives should be the same. As long as your wheel splines are in good shape, I wouldn't worry about it.

What I am trying to determine is if the spring in my shaft is shot.

Hmmmm...not sure I can help you with that one. Check the Speakeasy...

kreece wrote:How much slop is normal in a cushioned drive shaft?

I'm sorry, but, while many machines have "slop," BMW's have "clearance" or, occasionally, "play."

The simple Yes/No answer to your question is: the spring in the cushdrive is pretty stiff and pre-loaded. There is no noticable "play" in the cush drive at all, ever. You can't turn one end of the cushdrive against the other with your bare hands if the cushdrive is properly working (except for U-joint play). You know how much compression you need to get the C-clip off!

You didn't say where and how you measured but If you had actually measured your 15-20deg between the U-joint and the coupling nut at the other end of the cushdrive, it points to a broken spring or other severe problems with the cushdrive. Or the U-joint is completely shot. But that's easy to see.

Extended answer:
'You sure it isn't the coupling nut splines or final drive input gear or the wheel splines? What mattcfish is aluding to is radial play of the entire drive train measured at the rear wheel: gearbox -> U-joint -> driveshaft -> coupling to final drive -> final drive wheel splines. 20deg radial "play" at the rear wheel is 1/18th of the circumference of the wheel and equals roughly to 4.5in radial play that is way too much play in drive train and you should be worried ... if you HAD measured it at the wheel. You didn't say.

Thanks Stephen. This is what I was looking for. I have the swing arm off the bike and the movement is at the cush on the shaft, so at this point I am assuming the spring is bad. I can almost get the clip off without a special tool. Will take it apart and see what I find.

Ken