Vintage BMW Motorcycle Owners

We have four transmissions from which we hope to assemble two good ones. The casting numbers within the bell housing differ in their final digits. Would someone be so kind as to explain the situation?

I've read that numbers cast into things like that refer to mold numbers used by BMW. But I've not ever heard of any documentation which breaks the numbers down to anything that would make sense. The numbers that you see are not part numbers.

Am I correct that the transmissions of all the models from R50 to R69 are identical in all respects such as gearing . . .ect.?

According to Roland Slabon's book, there are minor differences with changes over time. They used different lubricants due to seals being change, so it depends on the bike's serial number. Of course there were different gear ratios for solo and sidecar uses. This page shows service bulletins...you can see in the transmission section that changes were being made.

http://www.beemergarage.com/bulletin.html

Your's is an interesting question, and I don't know the answer and I'd certainly visit Roland's website for endless entertainment and information. I'd also find the factory "Ersatzteillist" or parts books, two early examples shown here, and assume that for any particular part if the part number does not change over the years, that it's interchangeable over the years? The modern parts books have a silver or orange cover, are easy to find/hard to read. I'd guess that your four gearboxes are relatively newer? Other than for the "S" mark and the odo bushing retainer screw, I don't know how to tell a early gearbox from later? Someone else will chime in on this.

Thanks all for responding. I'll go ahead and order all the bearings, seals, gaskets, plugs, and washers for the R69 from the parts manual and figure they'll fit whichever case castings we opt for. Sure do miss Vech and Richard.

Nice to know y'all still out there

Douglass