I have been plagued by this clunk that I have in my 2006 g35. The clunk is prominent on biggg bumps, bumps at an angle, when one wheel takes a hit, and weight transfer. When both wheels take the hit evenly the car doesn't seem to clunk. The noise is definitely coming from the rear and seems to be worse with weight in the car (or the lower the car is). The car drives well and does not seem bouncy, the clunk can be felt in the steering wheel though. Harder the car hits, the louder the clunk (if it clunks). The clunk also happens on weight transfer even when the car doesn't hit a bump. Strictly weight transfer and the car still seems to clunk. Noise also seems worse in the cold.

What i have done/checked on the rear:
Fortune Auto True coilovers
SPL rear camber arms (with lock out)
SPL rear toe arms (with lock out)
SPL sway bar endlinks (rear link is adjusted for max length)
Energy sway bar bushings

checked:
all nuts and bolts
rear axle nut torque (big nut)
bushings
ball joints
emptying trunk (does seem to help but still heard a clunk)
tighten down my spoiler on the trunk (couple 10mm behind the trunk cover)
subframe nuts
top coil over nuts
rubber gasket between coil over and body

I am starting to think its my Fortune Autos. I bought them from a friend who used them for 10k miles at most. his car did not clunk. they sat for a couple months and then i threw them on my car. car does not bounce, no oil leaking out of the tops from what I have seen. I dont think its the coils just dont know what else it could be.....

 

Sunroof.

 

Yep

 

lol, seems like a common problem. Any other possibilities as the noise really does sound like it comes from the trunk, although the noise is consistent with something smacking the body (like a sunroof rail/frame).

Does the sunroof just need to be bolted down tighter?

I have been thinking of doing GT spec bracing, will that help with more body rigidity?

Thank you for the quick replies.

 

It sounds like you've checked all the other possible culprits. Specifically it's the sunroof frame, you'll need to drop the headliner to tighten it up. Recommend using locktite on the bolts when you do.

Bracing always helps with handling, not so sure it'll help this particular knocking problem though.