I have a '71 R75/5 and have been told that I must have a $575.00 special mount to mount a sidecar. I was wondering if anyone could tell me whether or not this is true.
I believe the 1968 models were the last ones to have a full perimeter frame. The /5, /6, /7 models have a very puny bolt on rear frame section.
A full sub-frame or sub-frame brackets should be used for a solid sidecar mounting.
Lonnie
Northwest Sidecars
This is a corrected post!
Lonnie you are WRONG!
the /5/6/7's all have full frames.
the engine is bolted in between the lower part of the frame, same as the earlier /2's.
the bolt-on REAR of the frames ARE weak, and require beefing up with a subframe, mounted to the lower frame under the engine, and going back to the passenger foot rest area, then up to the rear frame member.
partial frames with the engine being the lower frame began with the K bikes.
subframes are used on the /5,6,7 bikes because the frames are not strong enough, and give a better mounting place instead of using 'U' clamps on the thin walled frames.
Where would I get the subframe for mounting a sidecar to the R75?
Bob,
You are correct. Looking at my rogues gallery I note the front of the frame is still there. The rear section is pretty pathetic though. Remove two small bolts and everything drops onto the rear fender. Not a high point in German engineering.
Not being a Beemer fan I don't have that much experience with the beasts.
Maybe a dozen installations in the last 20 years. Mostly K's.
I will correct my posting.
Thanks for the heads up,
Lonnie
OK. Lonnie.
your right about the rear section being weak. that is the main resaon for the subframes on those models.
Bob H...a great subframe can be bought from Claude at CStanly Motor Works
cstanley@sunlink.net PA
also at Dauntless mentioned above. WA
Garyt Haynes at Sidecar Magic Shop also makes subframes.
www.hackd.com/sidecarmagicshoppe.html WV
San Jose was selling frame braces for a while because the frames flexed too much for many solo riders- especially in racing applications.
I've worked on a couple of older R models that also had swingarm braces. To eliminate flex?
Lonnie
I built my 'subframe' using a photo sent compliments of Velorex. Velorex
said that they used to have them made by an old guy down the street...he died.
There are 2 parts to the subframe . One is the part underneath the lower frame tubes that installs on the motor mount bolts and provides a place to clamp the lower rear hack mount. The other is a stiffener that connects the BMW rear frame sides together, a piece of flat bar fitted with bent ends/drilled and bolted into the secondary rear shock mount holes. Mine lies out of the way on top of the rear fender. This stiffener keeps the BMW frame from spreading or bending when the stresses of the side car are in force. Some folks use the upper front
BMW rear frame mount bolts/holes to do the same thing. However, the
tool tray will be compromised.
Finally, an upper rear hack mount has to be located. I put mine through the same upper rear shock mount hole as the stiffener. I enlarged the hole to accomodate the hack mount male side.( Actually, I made one because the old rig I got was lacking one male connector mount)
Mine works fine and will fit other BMWs, but if you have the $$, buying is easier and much quicker. Jon
Originally written by Bob Hunt on 8/27/2007 6:19 PM
I have a '71 R75/5 and have been told that I must have a $575.00 special mount to mount a sidecar. I was wondering if anyone could tell me whether or not this is true.
John, sorry to say that is true, unless you have the material and equipment to make your own.
you will also need a set of proper mounts for the SC and bike...these will run about $100 a pair [bike and SC] for each of the 4 mounts.
OOOPS. I forgot to mention, some subframes bought INCLUDE the bike-side mounts in them already. you will need to purchase the SC halves of the mounts. or adapt whatever is on it already.
Clevis and eyes are noted to be most popular.
