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Thread: Spoked Rear Wheel, Disc Brake

  1. #16
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    Quote Originally Posted by Darryl Cainey View Post
    Any final drive can be converted over to drum brakes.
    +1
    This '78 began life with a snowflake disc. Just tap the FD for the brake arm, good to go.
    Ride Safe, Ride Lots

  2. #17
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    Quote Originally Posted by Darryl Cainey View Post
    Any final drive can be converted over to drum brakes.
    Now, that's a totally different approach!!! Details??
    Last edited by EMSimon; 08-22-2013 at 05:36 PM.

  3. #18
    Sir Darby Darryl Cainey's Avatar
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    you have to get a brake drum pivot pin and the actuating cam as well as brake shoes.

    The final drive housing has to be drilled for the cam and tapped for the pivot.

    you will also need all the mechanism for the brake pedal if you don't have it.
    Ambassador BMW MOA Ontario Canada
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  4. #19
    Registered User lkchris's Avatar
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    When you do convert to rear disc you'll will have a not likely better performing rear brake PLUS lots more hassles whenever you want to remove the rear wheel. A change the other direction would offer more benefits.
    Kent Christensen
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    '12 R1200RT, '02 R1100S, '84 R80G/S

  5. #20
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    Side by side comparrison

    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.

  6. #21
    Sir Darby Darryl Cainey's Avatar
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    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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    Ambassador BMW MOA Ontario Canada
    President Niagara BMW Riders #298
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    1977 R100RS, (Retired) 1993 R100GS (just getting started)

  7. #22
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    Quote Originally Posted by 69ZEFF65 View Post
    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.
    Ride Safe, Ride Lots

  8. #23
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    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.

  9. #24
    Registered User lkchris's Avatar
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    Quote Originally Posted by EMSimon View Post
    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.
    Kent Christensen
    21482
    '12 R1200RT, '02 R1100S, '84 R80G/S

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