When i hit a big bump, i hear a very loud... noise coming from the back of the car. Sounds like a very loud creak... like how an old mattress sounds when somene jumps on it, but pretty loud.
My car only has 20k miles on it, so if its a suspension issue, i would want to get it checked out.

I have a sway bar + 10'' wheels in the rear, but the wheels are lighter than stock. I never got to preload the sway bars so that could be it. let me know what you guys think it is.

 

I say go to the dealership, you sit in the passenger seat while the tech drives the car.

 

Have you seen the thread with the cracked rear subframe......

 

More than likely, it's either your sway bar or the end links. Do you have an adjustable after-market sway bar? If you do, you may want to adjust the setting to see if the noise goes away. Also, check the end links to see if there's any play on the bushings.

 

I have the same thing and have had it ever since I installed the after market exhaust. It's real close to the hotchkis sway bars. It seems to do it more when its cold outside.

 

souds like the exhaust is slapping the under carriage like A ******* slaps the A$$ Of A Hooker. or maybe its something else... I just like that analogy.

 

check to see if the sawy bar bushings have grease on them.

 

Its not the exhaust slapping. Its a creaking noise, not a metal to metal noise. I think it may be the endlink. I have to get it up to see, but its too cold outside.

 

+1 on getting all your suspension parts/bushings greased up. I had a horrible creaking noise start on my way home from a road trip (3hrs from home, mind you) and almost had my car towed home because of it... it was CONSTANT coming from the front, I thought the car was about to fall apart. Well, I risked it, and got everything lubed up when I got home and the problem was gone.

 

okay ill let the dealership know. They grease everything for me normally..except for swaybars. Where can i get teh swaybar grease for stock rubber bushings??

 

Did the rease fix the issue?
I have the same noise on my 06 and have hotchkis sways. They've only been on for a few months though and already the sound. I hope it's just grease.

The good thing about the sound? It takes my mind away from all the other sounds the Z has . Brand new car and it has more noises/sounds coming from everywhere han anything else I've driven. it sounds like a 30 year old car inside!

 

i havnt been able to do anything. I just got knee surgery.