My 06 h3 has a knock on the rear right side when I go over bumps, sounded like the shocks so i changed them and it didnt help. I went over every bolt etc... and just cant find the cause. Nothing inside either. Just don't know but its making me crazy any clues?

 

I read forums, checked everything for hours trying to find the rattle, thought it was the hitch, stuff in the back, a shock, etc. Turned out to be the door support just under the latch and striker. Must have loosened somehow. They are not adjustable, what I had to do is take the support off the swing door, just under the latch, looks like a triangular metal bracket and bend it a bit. I then placed it on the striker side as if to mimic the bracket closing with the door, and bent it until the bracket from the door and the associated bracket on the frame were snug. Mounted it back on the door and rattle gone! This drove me nuts for months! I used a 5lb sledge to bend it, I'm sure there's easier methods, but it worked for me.

 

Had that exact problem once. The tech just slobbed some silvery-looking lube/grease where the leaf springs come together and it went away.