Recently we had a phone call from a potential customer concerning the handling of a friend’s sidecar that he had to drive for a fund raising event. Although he was not normally a sidecar rider he was able to determine something was not right with the way it looked and drove. After discussing the potential problem over the phone he said he would attempt to drive it slowly to our shop so we could look at it.
First glance at the rig showed that the bike was leaned toward the sidecar causing most of the pull to the right.
The customer was not able to tell me who mounted it but I suspect it may have been a first timer doing it at home. I also would assume it started out level but because of the poor mounting system it probably slipped while being used.
The most interesting part of the mounting was the lower rear attached to the swing arm of the bike.
The idea for this may have come from seeing that years ago Harley had the lower rear mount of their sidecar also connected to the rear swing arm.
Fortunately Harley did a better job of attaching the mount. What the installer missed was that at the time was that the mount was very close to the swing arm pivot which reduced the vertical movement at that point. The most important thing missed
here was the fact that the Harley sidecar was of a three point design with the upper front arm intended to flex slightly to help absorb some of the input from the sidecar wheel that like all Harley sidecars up to the end of production, had no suspension at the wheel.
Being a four point mounting system you can see the lack of triangulation between the upper and lower rear arms. Combining this with the up and down travel of the swing arm it probably did not take the rear of the sidecar long to start sagging.
Actually if the upper front strut clamp had been aligned better with the mounting point on the sidecar frame it may not have rotated around the bike frame tube. The strut would probably have done a better job trying to keep the bike from sagging to the right. The clamp was probably a lot closer to straight in the beginning but may not have been tightened enough to keep it from slipping.
The mount used for the lower front can be made to work in this position however I have had less trouble with other brands slipping that with the Velorex clamps. Actually the clamp in this situation did not appear to be the problem with the mount seeming angled down but rather the angle the new tube was welded to the original Velorex curved arm. It is easy to see it was not square to the other end of the tube going into the sidecar frame.
Because the sidecar was designed to be mounted on a light weight two stroke twin cylinder motorcycle, with a much shorter wheel base than the Sportster, the lower front mounting arm does not allow the sidecar wheel lead to be located back where it
should be. In order to solve this problem as well as assure there would be no more problems with things slipping at the
rear, I made a couple of modifications to the frame to allow the use of more modern boss and clamp arms.
First I welded a new pinch tube on the rear of the frame to eliminate the use of the stock sheet metal clamp that is notorious for slipping on the sidecar frame. If you look closely you can see in the rusty spot on the sidecar frame where this one appears to have been tack welded to stop it from moving. This also spread the lower mounts farther apart on the sidecar frame.
On the front I used the machined part of the tubing used for the original curved arm to make a clamp. This allowed me to move the sidecar wheel lead back to a better location which cuts down on low speed tire scuffing and in some cases will help to reduce head shake.
I also moved the upper rear mount using our own custom grade 8 eye bolt to replace the stock upper rear shock bolt. With these
changes we were able to properly square up and align the sidecar properly.
I also used our dedicated Sportster mount set shown below. Safe Riding – Barry