I have the same issue, but only on the rear passenger side. I took it to the dealer, and they blamed my HKS coils. They also said my endlinks are perfect. I then had my mechanic drop the shock and tighten the top mount nut. No improvement.

This has been going on for over 6 years. I love my suspension. It's perfect on 3 corners, but the noise on the problem corner really has me frustrated.

 

I get a slight creak/thunk from the rear passenger side at low speed on occasion, but disappears at medium and higher speeds. I have tightened everything and have never found a cause on this. I even had the dealer check it out and they couldn't find anything, though I don't think they looked very hard.

 

my Dad's G35 has this. He took it to the mechanic and he said that it was the top hat for the strut that had to be replaced. Suspension is stock on stock on stock.

 

+1 check your top mount sometimes the bolts can shear off like other people have been saying. It sounds like your strut is loose somewhere. Maybe check the bushing the strut connects to on your control arm.

 

That noise is more than likely the compression rod...not the bushing of the rod, but the actual ball joint/socket portion of it which is fastened to the spindle/knuckle. I've seen this many times before...the entire comp rod needs to be replaced in order to get rid of the noise. It is a tough one to diag on the hoist...you can use a large channel lock and squeeze the ball socket end of the compression rod to see the play, or you can actually diag it pretty easily on the ground. If you drive the car very slowly and tap the brakes (with a bit of force) you will actually see the entire wheel of the suspected side, jerk aggressively. It actually works a bit better if you're testing this while slowly reversing. The siuspension will always tend to move some while doing this (on a good G), but the front corner with the issue will have more moverment.

The only other thing that it could be is the strut. However, you have to load the strut to test it. Lower the G's control arm onto a jack stand (car is on hoist), and compress the strut. Grab the strut's piston and shake it...if you hear the knock, then replace the strut. If you have to, test the other strut and compare.

But my money's on the comp rod...

 

I know it's been a long time but if I recall correctly it was the end links.