:scared: I had my car up on a lift today and found the cause of the thump when turning hard in reverse. There is NO stop on the back when you turn the sterring wheel all the way. Going in reverse pulls the front wheel into the anti-sway bar. I could see where the wheel/tire rubbed the rounded section of the sway bar. The thumping part is the wheel weights hiting the sway bar. This can be very bad, as it may knock off a wheel weight or move it. Make sure to not turn too far when backing up!!