Sometimes when I make a turn I hear and feel a "KLUNK" from somewhere behind me. It sometimes happens when I'm stopped at a corner and begin to make a turn. It almost feel as if the car behind me has bumped into me. Today I was making a slow turn in traffic and it started going "KLUNK" "KLUNK" "KLUNK". It only happens when I turn left or right and not all the time. Any ideas.