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Spoked Rear Wheel, Disc Brake

EMSimon

No longer a member here
I want to convert my 78 R100S from rear drum to a disc brake. I have all the parts I need, but I can not find a spoke wheel with a disc brake hub???? All there is are snowflakes. Are they THAT rare?
 
Didn't the early R100RS come with spokes? Assuming it had a rear disk, then they might be pretty rare.
 
How about the S? I know there was a 1978 R100S with a rear disc. What wheel did that have?
 
Does that mean, I cannot get a spoke rear wheel with a disk brake? I have to get one made?
 
Why are you trying to reinvent the wheel> pun!

Not saying it couldn't be done, why don't you just get a pair of Snowflakes with a rear disc.
 
Why are you trying to reinvent the wheel> pun!

Not saying it couldn't be done, why don't you just get a pair of Snowflakes with a rear disc.

I don't like the looks of the Snowflakes and I hear all these horror stories about them having flaws.
 
Only the ones that haven't been taken out of service for the recall. Other than that, they should be fine.

I wouldn't know how to tell black from white. But the main issue is really the looks. The Snowflake wheels to me are an 80s BMW. A 70s Airhead needs to have spoke wheels. Especially a R100S.
I don't think Snowflakes would look good on a R90S either.
 
You might consider calling Woody's Wheelworks and discuss the situation with them. I wonder if you had a rim and hub, could the wheel be respoked with enough offset to allow the use of a disk brake. I suspect some engineering will be needed on the frame side to mount the caliper as well as the master cylinder.

It's sounding like this combination never existed in production...maybe for a reason...maybe not. But worth a question to some wheel experts.
 
How about the S? I know there was a 1978 R100S with a rear disc. What wheel did that have?

Disc on snowflakes only, or aftermarkets (Lesters, etc.)

Why do you want the disc rather than a drum? If you're looking for the spokes to give that "period authenticity/appearance", i would think that a drum set-up would enhance that look, not detract from it. No?
 
You may need to have a hub custom built

I don't think your going to find a OEM BMW spoked rear wheel or hub to fit your bike that mounts a disc brake, I don't think they made them OEM. I'm almost certain that if there's a Lester rear wheel disc brake it will not be for sale. I know that Morris mags are out there (I have a set for a pending project) and they do make a rear disc wheel for Air heads but you will need to fabricate a caliper mount. Morris mags look almost like Lesters but just a little lighter in weight and a little better looking in my opinion.

Woodys Wheel Works is an excellent resource and vendor for custom stuff and the staff has a wealth of knowledge regarding what works and what might be a very expensive and unproductive experiment.

I had given thought to having a disc mounting adapter made for a spoked wheel hub until I compared the stopping power of the rear disc on my R 100S and the drum brake on my R 90/6 and found that there is not much of a difference between them.
 
At one of the rallies, I saw a R90S with a rear disc brake, that the owner had adapted.
The main reason I wanted to go with a rear disc was the final drive (imagine that):banghead I found a brand new 32/11 final drive which I would like to install, but it is for a disc brake application.
 
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.
 
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.
 
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.
 
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