Yikes, sounds like a home made death trap rig story!
On the other hand... I love the way my sidecar rig handles.
I attribute that quality to a solidly constructed frame and proper alignment.
Since purchasing second hand, I've replaced the sidecar shock due to a bad irreplaceable bushing, also a worn swing arm bushing, and put an actual sidecar tire on. Replacing these regular maintenance items all made drastic improvement.