Abracadabra: White rubber disk on drive shaft bell disappeared

[Micha]

Yesterday I came back from a trip of about 100 km.
When I parked at home again, I noticed that the driveshaft rubber disc was gone. It was in great shape and now it's just gone. The truth is that it made me laugh. There are not even any leftovers
Anyone familiar with this phenomenon?

[Slash2rider]

Magic!I followed easy route,cut glue one minute job may put some insulation tape so it doesn't repeat.Knowing you it won't be that easy.

[niall4473]

Micha,
if having things fall off your motorcycle, never to be seen again, makes you laugh, then I strongly recommend that you dispose of the R51/3 and get yourself a late 1960s Triumph, your sides will be aching!

[strichzwei]

Made me laugh!!!

[Micha]

I see what you mean, but having owned a BSA M20 for decades, this is where I laugh, whereas with the BSA I cried.
Theoretically, if someone were to travel the roads I was on with the BSA dragging a huge magnet behind him, there is a high chance that he could assemble half a motorcycle from the parts that would stick to it.
These 2 bikes were designed more or less in the same technological period, and one can only marvel at the high level of the German bike, compared to the stubborn and and puzzling conservatism of the English to create motorcycles.

Anyway, today I was in the parking lot and I attached some pictures. It can be clearly seen that this rubber disc has been melted or eaten away while the shaft was turning. It must have had a high friction against that metal bell.
Another thing I noticed, is the angle of entry of the drive shaft into the metal bell cover, it seems to me that it is not centered, on the other hand, does it have to be centered?

[schrader7032]

The small donut departed my R25/2 shaft a number of years ago. I bought a replacement, but haven't gotten around to putting it on...technically, it has to be pressed on once the shaft is disassembled. I decided to try a small plastic ring from a juice container...cut a slit and slipped it over. Probably not really a 100% replacement, but makes me feel better!!

In your case, the small area that the original donut rides on the shaft appears to be shifted towards the bell housing. I don't think the donut is supposed to touch the bell housing.

[Seek]

On my R25 the rubber puck doesn't touch the bell housing. You should carefully check if everything is still properly tightened. Especially the nut in the cardan coupler could come loose. Or the threaded ring holding the pinion tight into the casing. I don't know if this would cause a similar problem, but better check before something more expensive comes loose.

[FL54]

I see what you mean, but having owned a BSA M20 for decades, this is where I laugh, whereas with the BSA I cried.
Theoretically, if someone were to travel the roads I was on with the BSA dragging a huge magnet behind him, there is a high chance that he could assemble half a motorcycle from the parts that would stick to it.
These 2 bikes were designed more or less in the same technological period, and one can only marvel at the high level of the German bike, compared to the stubborn and and puzzling conservatism of the English to create motorcycles.

Anyway, today I was in the parking lot and I attached some pictures. It can be clearly seen that this rubber disc has been melted or eaten away while the shaft was turning. It must have had a high friction against that metal bell.
Another thing I noticed, is the angle of entry of the drive shaft into the metal bell cover, it seems to me that it is not centered, on the other hand, does it have to be centered?

I, too have a BSA M20 that I picked up as a winter project last year. Compared to a BMW, they are very primitive and rough riding. I don’t have enough confidence in it to take it for an extended ride whereas I ‘ll ride the BMWs anywhere.