i have that aswell have had it from new car has been back to dealers 3 times so far and they have found nothing wrong they think its the magnets in the electric steering whereas i dont and typically when they take it ut for test drive it doesnt happen
Mine only does it when turning to the right so that I can reverse onto my drive and then only does as the brake is applied, seems to be from the servo motor area for the steering column, could so easily be the UJ in the steering arm or the reduction gearing from the steering servo motor, either way it was up on the ramps yesterday for it's MOT at my friends garage in Liverpool and all the important bits are spot on. Those giant puppets are superb by the way.
My Corsa used to do this, had a very similar suspension set up at the front.
Between the anti-roll bar and the suspension leg there is a very long link rod with a ball joint at each end. It pretty much ties in a knot as you turn the steering.
These wear like nobody's business into the straight ahead position and cause a "crack" you can feel through the steering when you start to turn. Oddly, it was always when turning right too.
A new one would cure it for a few months, I got used to the "crack" in the end, it was easier to adapt than repair it every few weeks.
Got a 2006 sve 1.5 diesel , had a knock on the steering since i bought the car in Jan 20012 , not ever time i turn only now and again .It just failed it MOT on the front suspension arms and a broken coil spring . Think the spring was a very bad pot hole i hit a few months ago.
anyway had them done so far so good no knocking . bit early to be sure but will update in a few weeks time.