Forum bmwbike.com

Follow up to my post about the clutch. I was riding at about 50 mph, when it felt like the cluch was completely slipping. I could put the bike in any gear, and I could feel the "clunk", heard no clatter, but not forward motion. At a dead stop, with motor off, I would put the bike in 1st gear, and no resistance when I pushed the bike, i.e., didn't feel like I was turning the motor.

Now, with the kick start, I can spin the motor. With the transmission out of the bike, I can turn the spline in the front, and the output shaft on the back spins.

I took the clutch assembly off the bike, and it is in very good shape, well within spec.

Should I be looking at the rear hub?

Sorry, I didn't finish the post - does it look like there's a transmission problem? How can I test the transmission, other than what I mentioned above?

Hi Jon,
Firstly narrow down where the problem lies. If the gearbox is okay, as from how you describe things it most probably is, go on to the final drive. Is the drive shaft turning the bevel drive? The splined female coupling at the end of the shaft is held on the shaft by a taper and a nut that should be very tight. However, it has been known that the nut was not torqued up correctly and the coupling became loose (I know, I was riding the bike at the time) giving the same symptoms as a failed clutch. Check that and report back.

Gerry

Oh boy. I learned a good lesson here. I should have started at the back, and worked my way forward. I took the rear wheel off today, and the spline unit on the hub that is held on by 10 rivets sheared all 10 rivets! Probably could have saved a lot of time and heartache by pulling the rear wheel first...

Is this common? I hear all about the splines wearing, but not this. I assume the rivets are available? What do I need to do to put them in? Frankly, I may just run this over to the dealer....

Thanks for all the input!

Hi Jon,

Well, I have never heard of that one before in all my 30-odd year of tinkering with BMWs! You see, it was sheered rivets after all. Don't take it too badly; I doubt if even the most experienced engineer would have guessed that was the problem.

Don't evn try to repair it yourself, it's not worth the hassle, plus either the hub or the splined boss will have suffered some degree of damage. Your best bet is to purchase a good second-hand wheel or hub complete, it will be the cheapest and most durable option.

Good luck,

Gerry