Your lower mounts are the type that are known to fail. Your upper rear mount is a Motovation sidecars mount and is installed in a way that it is very likely to slip. Normally the mount is placed on the main frame down tube and is of a type much less likely to slip then the Motovation mounts. Also it is installed in a manor that the forces applied are not trying to rotate it around the frame of the bike. In other words in line with the strut. The lower front is an early California frame clamp that is known to fail. Latter ones have 1/4 inch bolts to keep the "U" part from coming off of the block. Also it is installed improperly in that it should not be on curved section of the frame. Where it is installed not only does the frame curve up but also in. While these mounts have been working in the long run I would not trust them. The ball collet mounts California has some fail before they ever got out of the parking lot and these failures may have contributed to them going bankrupt about 30 years ago. There are several issues with these ball collets, the collet with even a slight amount of where on it or the ball which is a soft material called leadalloy the collet will pull off of the ball. Your upper rear mount is installed correctly however it to is the type of frame clamp that is known to fail. The lower rear being mounted higher then the lower front makes it hard to set the alignment as when ever you change your lean out, your toe goes the wrong way. So if you are trying to fix a pull to the right, you would lean the bike to the left which toes it out causing more of a pull to the right.
Lots of ways you can fix all of this, we of course offer mounts $775. Our mounts do use frame clamps for the upper two mounts. The lower front mount clamps to the frame tube and picks up the engine mounting bolt. The lower rear replaces the center stand and ties to the side of the bike putting the mount aft of its current location and below the muffler so that it is closer to the same distance off of the ground as the lower front. You would also need to replace the bosses (the part with the collet) these run $65 each you have a 45 degree and a 70 degree at this time and you would need two hiem joints $40 each. You could also drill for cross bolts on your upper rear, relocate the upper front, and fabricate new lower mounts doing away with the ball collet set up. I have personally had every one of these type of mounts fail on me when running a GL1100 friendship 1 rig.
Jay G
DMC sidecars
www.dmcsidecars.com
866-638-1793
First post: "...sidecar deal I couldn't pass up."
Later on in the thread: "Everything is wrong. Your side car is more then likely going to collapse into the bike catastrophically without warning."
I guess this means I shouldn't dual sport the rig before correcting and reinforcing the mounts. 
Well this sidecar rig just became an interesting project. Gonna have to go back to the drawing board and do the sidecar theory and design research I have been putting off while focusing on getting the bike running proper.
Thanks for taking the time to point out areas of concern and the flaws in my rig Jay. I really appreciate it. The knowledge definitely helps me get up to speed on the project. When I have a plan together I will certainly contact DMC for parts and supplies as needed.
Can anyone can help me with the following:
Besides the written works of Hal Kendall what other sidecar theory and design books are recommended reading?
Does anyone know of a GL1100 Friendship I sidecar build thread or photo gallery on this forum or elsewhere that has pictures of a properly set up rig with all the mounting parts issues corrected and the mounts properly placed?
Thanks.
We have the book "Driving a sidecar outfit" $34.95 lots of good information there. I have attached installation instructions for the GL1100 as well as alignment instructions.
Jay G
DMC sidecars
866-638-1793
www.dmcsidecars.com
jaydmc - 8/9/2016 10:30 AM We have the book "Driving a sidecar outfit" $34.95 lots of good information there. I have attached installation instructions for the GL1100 as well as alignment instructions. Jay G DMC sidecars 866-638-1793 www.dmcsidecars.com
Thanks for posting the files. Found the book on DMC site. Looking forward to it.
Why do you like to replace the windshield with a full height windshield?
My dog coming on motorcycle rides is the reason I bought the rig. The little windshield is to short to protect my dog while riding in the sidecar. The shorty also won't allow a roof to mount over the dog's head. If the rig was primarily to be a show peice I would leave the windshield as is or more realistically would have bought a motorcycle without a sidecar.
I have been trying to understand why the mounting of the sidecar wasn't more proper. It dawned on me today when the car was mounted they placed the mounts around the front fairing and rear side bags. Those peices are off and won't be going back unto the bike. Without those peices there will be more access to the frame with better mounting angles. I hope that is the case especially for the rear upper mount. As it is currently it cramps up the legroom for the driver.
May be it will be easier to make vinyl extension for your top instead replacing windshield.
Thanks for the input. It would be a good idea except dog would have a tough time getting in, couldn't sit up all the way and more often then not the roof won't be on the car so the dog would still be stuck without enough protection. Also I am not sure how much longer the shorty windshield is gonna be a viable windshield. Judging by the weathered paint job and paint lines showing a full height windshield used to be installed and because the car came with the original cover more then likely the small windshield used to be a big one that was cut down due to deterioration and cracking. What is at issue is the rig was bought new, built and ridden a long ways by its first owner. When they past on it was left to someone who only rode it a few times and mostly let it sit outside for many years. Everything is really heavily weathered. The upper photo looks ok because its from the side. Looking down on the rig is different story. The little windshield looks ok though I wouldn't trust it enough to spend money in a custom top for it in case it cracks and deteriorates further leaving me with having to buy a new windshield anyway and then another top to boot. I would like to use the original top too so the windshield really does need to be tall and close to OEM spec. In other words I want my dog to be comfy while maintaining the OEM looks and style like the below pictured rig.
I just went out to have a close look at the windshield situation. When in close I noticed most if not all mounting hole screws are cracking in the little windshield. Definitely gonna be needing a new windshield sooner rather then later.
Like Al said "Just be careful and buy their plastics bit if you do buy from them. It's not expensive and it works much better than a standard twist bit" it will save you a lot of problems. I use only nylon bolts and lock nuts on all of my sidecar windshields, and do not tighten them up too much. At least with the nylon bolts you usually break the bolt instead of the windshield when cranked down too tight.
Nylon hardware is great idea. Much more affordable to beak some bolts then crack the windshield. I will definitely use nylon for the hardware. I hear using foam tape behind the windshield helps cushion the plexiglass to alleviate stress too.
The foam tape is a good idea but thicker is not always better. If you use tape that's much thicker than 1/8th of an inch you will either pull each screw down so that it forms a dimple [and cracks eventually] or leave it so loose that to moves in the wind [and cracks eventually]. Generally tape that is not too thick and on the dense side is best.
