People who have rebuilt an early 1970s
bottom end will recognise these parts.
For others, this is the main gearbox shaft from an early 1970s
motor. One end has a sleeve gear with a spline for the rear drive sprocket and the other end spline is for the clutch hub. I have taken the sleeve gear off the shaft to show the shaft better.
Earlier motors have a key driven clutch hub and later motors have needle roller bearings in the sleeve gear where this one has sintered bronze bushes.
The sleeve gear spins on the long shiny part of the shaft and this feature of the gearbox design is sensitive to how well the gearbox oil lubricates those sintered bronze bushes. Poor lubrication causes the shaft and the bushes to wear and eventually failure of the teeth on the sleeve gear due to misalignment from that wear which is a fairly common failure mode in these motors.
The shaft with the gears on it is from a Basket Case (1971/1972) model 85
Alpina and the long shiny bit and the bushes are in fairly good condition considering how old it is. I was going to use this shaft along with new bushes in a motor I am rebuilding.
However a couple of weeks ago the other shaft (which is new-old-stock) popped up for sale on eBay and I bought it for a reasonable price. I was expecting there to be some corrosion to clean up after all it has been sitting around in that plastic bag for about 49 years, but it looks perfect.
It's fairly amazing to still be able to buy new parts for a bike whose manufacturer went out of business 40 years ago.