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Spoked Rear Wheel, Disc Brake

I found these pictures on the Morning Reads (sorry for borrowing it)

So it can be done!

Custom R80 with spooked wheels and a rear disc.
 

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I have the disc final drive from my '79 R 100S (smooth case old style) sitting on the bench right next to a spare drum brake R 90 final drive. The disc F/D has the tapped hole for the brake shoe pivot and the hole for the actuating arm in the casting. The pivot hole has a threaded plug and the arm hole has a plastic cap on the outside. Here is the only difference in the disc brake F/D housing and the drum brake F/D housing that I see. The drum brake one has an additional ridge(no other way to describe it) on the inside face(brake drum and shoe side) that the brake shoes appear to rest on when brakes aren't applied and keeps them aligned properly. The ridge is not on the disc brake F/D housing that I took off my 1979 R 100S. I haven't tried to install drum brake shoes on it but I have to wonder if the lack of that ridge would make it impossible or unsafe to do so. I installed a later(ribbed/finned) drum brake F/D on the bike with same gearing to convert to drum brake.

without seeing it, my first guess is that "ridge" was not a built-in design for shoe alignment, but the remnants of the original face of the inner drum, with the area where the shoes rest is what has been worn down by braking friction.
 
Pictures might help

I will see what I can do to get a picture or two of both F/D's and post them so the difference is clear. The missing ridge on the disc brake F/D isn't due to wear. It was never cast into the housing from the factory. The castings are clearly different.
 
I don't like the looks of the Snowflakes and I hear all these horror stories about them having flaws.

You're dealing with two misconceptions ...

flaws in Snowflakes
rear disc is an improvement over the drum brake

But, so did USA dealers, as in the early 1980s BMW attempted to reintroduce spoked wheels with the R100CS, but USA dealers refused this and all USA versions came with Snowflakes AFAIK. A quick check of realoem.com reveals that the spoke wheels for these bikes had rear drum brake. But, it is a source for a front wheel hub that accomodates Brembo front brakes.
 
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