What is the clunking sound on my BMW?

I have a 2003 BMW 330xi and when I back out of the driveway and turn the wheel to the left, I get a hard knocking, or clunking sound from the right front end. Any thoughts?What is the clunking sound on my BMW?In addition to checking the control arms and bushings, look also for wornout brake pads and rotors. The latter even if still thick and within specs may be ridged and make this kind of noise specially if brake disc pad grease was not applied during the last service or if the grease is already gone/caked off.What is the clunking sound on my BMW?lower control arm, they wear a lot on BMW, make sure when you replace to replace both at the same timeWhat is the clunking sound on my BMW?I'dook to lower control arms, or the thrust bushing. problem on my '04 3er