2 replies [Last post]
1943 WWII BMW's picture
Joined: 05/09/2017
Posts: 1

I have a 1943 BMW R75 with sidecarthat I need help on. The whole bike has been lovingly restored and it runs but there are multiple problems that I can't seem to fix. ANY help or advice on ANY of the following would be greatly appreciated
1. Can't keep brake fluid in rear brake cylinder, or I have a bubble in the line that although I've tried multiple times I can't get to bless out.
2. High gear will nt work, in fact, if high gear is even slightly engaged, none of the gears will engage.
3. Think it's running mostly on one carb but not sure how to tell on that
4. It's REALLY leaking oil... I know they should leak a little, but it's getting to the point of ridiculous.

THANKS!! Added some pictures for reference

  • img_2770.jpg
  • img_2748.jpg

Nothing in the world is accomplished without passion.

R68's picture
Joined: 08/20/2008
Posts: 459
Interesting motorcycle...

...hate to know what someone paid for the MG42, but:

#1 Try the local brake shop, especially one that services german autos. The master cylinder was made by AtE, still making brake parts. You might contact them for help also?

#2 Poorly rebuilt gearbox? A fellow in Fredericksburg, Indiana can rebuild your's, take a nice drive down there?

#3 While giving it throttle, pull the plug on the "good" side: does it run on the weak side? If so, pull your carbs, substitute a set of 24mm Bings from a R50-R60 that you borrowed from someone, see if your originals need rebuild? For re-enactment, just use the Bings?

#4 Oil leaks usually result from seepage around the pan bolt holes. The threaded hole directly into the crankcase is very obsolete technology, but RTV or some sealant on the bolts will stop the leak. Don't use too much RTV. Of course, check the pan gasket and mating surface of the pan and case for warpage or damage while your pan is removed. Maybe you should dial in the bike without all that excess military bling/weight; that driver needs to go on a diet?...or...oil on the rear shelf: worn rear main seal...or...oil seepage from the top end: damaged head or base gaskets, loose cylinder base nuts...or...oil seepage from gearbox: poor rebuild, see above #2...good luck with your piece of history.

Bruce Frey
Bruce Frey's picture
VBMWMO #6316
Texas Hill Country, USA
Joined: 10/27/2006
Posts: 574
While i think it it is

While I think it it is possible to build a complete R75 from repop parts, the horror stories I have heard about R75 transmissions kept me from ever thinking about owning one.

Anecdotally, I have heard that:
1. There was a factory design flaw in the transmission that must be corrected to prevent failure.
2. Repop parts are not always interchangeable with factory parts or with other repop mfgrs. In other words, you may need to have all pieces from same source.

In Europe, Hans Peter Hommes is generally regarded as the R75 guru (and repop parts supplier). I have chatted with him at Veterama and English is not a problem.

If you search the Yahoo Kradrider forum you will find some R75 discussions.

Closer to home, Vech at Benchmark Works has restored an R75 and I would seek his counsel.

Good luck,


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