Forum bmwbike.com

My brother's recently restored and beautiffully running 1938 R51 has the standard front drum brake which, whilst satisfactory on the open road, in the cut and thrust of driving in Sydney, can sometimes be found a little wanting. Does anyone know where an effective "after-market" front brake assembly can be obtained that would readily fit this machine, provide better retardation and still look the part?
Not exactly a restoration query but the Ariel Verlag publication BMW Motorrader Typen und Tehnika has a picture of an R 68 in ISDT trim on page 93 which clearly shows two (2) carburettor bodies in the right hand view. One is at an angle and obviously bolted to the head whilst the other, in a more vertical plane, appears to be sitting neatly behind the intake tube, "hanging" by the throttle cable. Any ideas?

PeeVee

Philip,
I understand that the factory installed two carbies each side in an attempt to gain more mid range power. In the same book, have a look at the photo of one of the side car outfits (can't remember the page)... two carbies each side.
Lloyd

...Find a 1954 type full hub brake plate and wheel...much greater brake surface area and performance...

These single-sided brakes can be improved considerably by ensuring the drum is true by skimming, and by selecting a suitable brake lining material.

Many re-lining companies use standard stock material which might not always suit an older machine. There is a whole range of different materials available and although so far as I am aware BMW never published data on their brake lining material, they selected the best compound available at the time. Where original BMW linings are still available (for post-'55 models) they tend to be of a grey, fine grain, relatively soft compound. Ferodo made linings that worked well, but on a damp morning they were vicious enough to lock up a wheel!

Look around and ask other vintage bike owners what they use and what is available in your area. It would be a pity to lose the bike's originality for the sake of a little research.

Hi Philip,
as the writer of that book was a friend of mine; Heinz Härtel, I can help. The dual carbs on the R68 ISDT aren't really dual carbs, but an additional carb piston just in a tube, intented to be used after a destroyed piston by sand in the carbs. These boys were really clever during the ISDT events. The other dual carbs on page 178 are really dual carbs as this is the Apfelbeck engine with 4 radial valves per cylinderhead. Used on the BMW RS54 engine. So both outlet valves were opposite and each needed a carb.
As to a better brake for the R51, in the early fifties there were after market brake assemblies by Hoske and the writer Heinz Härtel actually owned a new R51/2 back in 1952 to which he fitted this drum. Perhaps Eric Bley can supply these. His son has that business in Chicago, Bley Enterprises or something.
Hope to be of help and if you have anymore questiuons don't hesitate to ask.

Wil ElbeRS
the Netherlands