Hi Guys,
I have an identical problem to Ben. I have an 2009 STR and this front right noise (and vibration through the floor) has been occuring since around last September (around 15,000km's on the clock). It is a very defined thumping/knocking noise and it varies in intensity and loudness depending on speed, amount of left turn, and surface. Generally the faster the wheel moves up/down, the more severe the noise and vibration through the floor.
It's now done 35,000km's and went back to Liverpool Nissan yesterday - for the 3rd time - but they still can't find a problem. Check wheel bearings, tighten body mounts, check torsion bars, check brakes, grease this and that etc. But to no avail, very frustrating. Their next step is to contact Nissan's technical dept - still waiting for a response.
My biggest concern it that if something eventually fatigues/breaks, I'll have an accident or be stranded off-road somewhere.
There seems to be a few forums with similiar issues so I'm assuming that someone, somewher knows the answer.
Cheers,
Geoff.