I had a similar problem on my 2.4 Stock. it started as a light bump and I assumed it was tools in my trunk (used to renovation work). It got louder, so I took it in to the dealer. The day I drove it to the dealer it sounded like the rear suspension was trying to slam through the underbody of the car.

Just checked my service slip it was the trailing arm bolts came loose. They had to replaced them and tourqed everything properly never had a problem since. ( this was almost 2 yrs ago )


only thing i can do? any other idea's? i might just call the dealership and see what they say

 

cut ur bump stops

 

already did that

 

cutting your bump stops at the rear may lead to coil bind or shock limit travel. Big bang. Dumb

 

thats probably your problem there. Like qwik said, without the better valving of the FE5 struts, your bottoming out and causing coil bind, which is not a good thing.

 

hey LS1f body...time for a new sig: PINK

 

lol, you know what, i will do it just for you john.

gimme some time with the 'ol MS paint, and i will make Mavens pink dreams come true

 

i think we are too hard on you. this pink theme is old now....damn i gotta getup and go to the machine shop and work on your stuff this am...see you in a bit. you going to afganland soon? or home? are you allowed to say? cmon....

 

not yet, all i can say is march sometime.

and i will have a finished product here for you in a wee bit

 

i cut them properly. i first did not cut the back bump stops at all and had the noise. then i pulled off the wheels and cut them the right length and i still have the noise.

 

Milkey I dont know what the right length is cutting bump stops, it did not help you. And long distance internet diagnosis is tough as you may have made a mistake if you are not a supertech like Maven.

BUT something I noticed the other day; there is a thick spacer underneath the top strut mount on the Cobalt. the fitment goes like this: spring (plastic ring underneath it on the strut lower plate against the bottom of the spring). then a spring, followed by a top plate, (a rubber ring underneath that against the spring) a white plastic bearing with the dark plastic side facing down, then the top cobalt strut mount WITH A THICK SPACER INTEGRAL TO THE MOUNT but this spacer can fall out while working changing springs. If you miss this, the center strut nut will bottom on the threads without letting the top plate anchor securely on the strut rod, SO if this spacer is gone, and you assemble everything onto the car it will clunk coz its loose.

just sayin'

 

it's not the front. it's the rear. all that is in the rear is the shock. no strut.

 

sorry missed that: loose or broken shock (mount0, twb mount or coil bind.

 

still have this problem. damn i don't think it's ever going to be solved unless i take the springs out and put stock ones back in for the back.

 

make sure you have your exhaust in all the hangers sometimes simple is the answer. my car does the same thing except my is from my anti sway bar clanking