Skip to content

USCA Sidecar Forum

For some extra information about navigating the forum you can go to Forum Tips

Forum breadcrumbs - You are here:ForumGeneral Discussion: Sidecar FAQBMW /2
Please or Register to create posts and topics.

BMW /2

I'm new to all this and am restoring a BMW R50/2 with a R80 engine. I have an older Watsonian GP to put on it.
Is there anything I need to watch out for? The frame has factory lugs installed.
What about the final drive gearing??

I wish I were more knowledgable about rigging sidecars, but I'm not. I do know that I hope you will show us all the final product after you get it rigged. I'm sure it will be a beautiful rig.

I have an original engine R60/2 thats been pulling a Sputnik and now a Ural. It is equiped with a sidecar transmission, but the final drive is the solo set up. The Ural tub is heavier and has significantly more aerodynamic drag so now it isn't quite geared low enough to pull in 4th gear (4th gear is the same ratio in both the sidecar and solo transmission). However your r80 engine puts out about twice the power of your original so driveability may not be an issue. The proof will be in the pudding.
I have broken one spoke on the rear wheel. So I'd say if your looking for trouble make sure to check your spokes for good condition (free of rust and pitting) and that the tension is good. You might also want to consider a thicker spoke for the pusher wheel since your increasing both load and power.

Have Fun

Lee, There are several things that worry me. I didn't know there was a sidecar trans and I have a 32/11 final ( I think ) I just re-spoked the rear wheel but noticed the spokes were actually thinner than the old ones.

Same thing happened to me. I ordered steel rims and chromed spokes from Germany and the spokes were a bit thinner than original. I had just bought the bike and rims and spokes had some pitting from rust. I hadn't gotten sidecaritis till the following year. One spoke out 36 breaking after a few years is not so bad.
32/11 are you using an R80 final drive ? I also have 84 r80rt which is as of today pulling the Sputnik. I think the /2 is better suited to sidecars. But I doubt I'll be converting the oldtimer.

I know it is a newer final drive. Not sure what from. I need to replace the gear though because it is way to worn out to use. This is my first experience with a BMW so I have to learn everything.

FYI - I had a R90 with a Watsonian GP on it. The spokes began to pull through the rim as the result of a flat tire wobble. I ended up with mag wheels - BMW Snowflakes. Adapting /6 wheels to your /2 might be an issue but the spoked wheels are a little fragile for sidecar service. Just Sayin'


I owned a BMW R80/7 rig with a Ural sidecar and have build several BMW rigs during the past 15 years. As long as your rims for spoked wheels are steel and not alloy and as long as you care about the spokes (tension) there will be no issues.
If you order spokes in Germany anyway, try to get them from Friedrich Menze Fahrzeugteile in a town called Hagen (just google for it). They are No 1 specialists in making spokes and spoking wheels for rigs. They offer reinforced spokes for sidecar application as well. Some of my customers with Harley rigs on original wheels had issues with the rear wheel spokes until I respoked them with Menze spokes.

Here is a picture of my 1965 R50/2 with a Steib S 500 attached. The R50 has a 1970 R75/5 motor and transmission

Attached files

Looks really nice, especially when one considers it's 50 years old.

If I remember right,32/11 figures out to be 2.90 which is auto-bon gearing. You will probably be doing a lot of 4th. gear work. Probably be happer with a 3.56 if you can find one.
Tex. rep

J.R, the final drive gearing might be a bit high (Autobahn) with the original engine. The 75/5 engine has got much more power. That should do quite well with the 18" wheels. It´s near perfect in my opinion

My R50/2 has the R75/5 engine and Dell Orto 32 mm carbs. I have been told that the Dell Orto 36 mm would be perfect.
For now I will stick with the 32's.

Attached files

Don´t you have any connector tubes to the airfilter? Or do you run the engine w/o airfilters at all?

The original carbs were 32mm Bing CV. From that view your 32mm Dellorto with pump are not that wrong, I reckon.

I have been working on setting up the DellOrto's. So I have the air tubes from the filter off.

The previous owner had too sharp of an angle on the throttle cables so that they were hanging up.

I have been working on a solution for a more " fair " route to the cables.

It is not easy with that big tank.
I think that the 32 mm Dell Orto's are just fine, but my carburator "Garu's" say that 36's would be better.

Attached files

You need to find a pair of right angle metal guide tubes for the top of those carbs. Given the limitation created by that tank, I think that is your best solution.


I have rerouted the cable to the outside of the tank rather than thru the tunnel. It seems to work ok now. I have put about 50 miles on her.


Attached files