Can someone advise what holds the pinion and bremstrommel onto the kardan shaft?
Mine has been welded together which makes bearing replacement a challenge.
Thanks for any replies
This is very interesting to me as I've just gone through this myself with my R52.
The bremstrommel (brake drum) is merely an interference fit on the shaft. For solo machines, the same is true for the kegelrad (pinion gear). Originally, BMW made the driveshafts for the sidecar gearing with the pinion gear machined directly out of the end of the dirveshaft.
My machinist tried to push everything together as BMW had done. The fit wasn't tight enough and after a short while it spun freely. He ended up pinning the pieces together to make sure that everything was tight, and that seems to be working now.
There's plenty of room at the back end of the pinion gear to drill across the diameter of the shaft, through both the gear and the shaft, and insert a pin. At the brake drum, he drilled a hole into the seam between the drum and the shaft, along the length of the shaft, from the front, inside the drum. Then he threaded the hole and screwed in a hardened set screw as a pin. So all of these fixes are removable and repairable, and you don't chance the heat from welding warping something.