Hi, my 420 makes the occasional klunk in the right-front suspension. It usually happens when I am turning, as into a drive, and there is a change in elevation which flexes the suspension. It is one klunk, and it does not repeat, nor does it happen every time, and I haven't been able to reproduce it at will. I have good brake reaction arm joints (did it myself, about 5000 miles ago), and I cannot find any looseness in the ball joints by jacking up and prying on things. Shocks and tie rod ends seem tight. Car drives and tracks perfectly. I also can't find anything loose in the torsion bar or bushings. I thought you might have a similar experience and be able to offer advice.