Thread: mystery noise

Hey everyone, I drive a 2000 grand prix gt that makes a really irritating thumping noise. I've been trying to identify it for about six months and im completely at a loss. hopefully someone here will be able to point out what I'm missing. Here's the basics.

-i noticed about six months ago. No fender benders or other obvious possible causes.
-definitely coming from front of vehicle somewhere
-thumping starts at about 15mph now. used to start at about 20 mph but has slowly gotten worse
-noise gets louder as vehicle gains speed, then levels off as it hits obnoxious.
-noise goes away completely if i take a right turn with enough speed to lean the vehicle to the left a little
-mostly goes away when i do the same on a left turn.

And this is where it gets mysterious for me lol. heres everything ive replaced in the last six months trying to find the problem. all with new parts and all to no avail. lol though on a bright note, she handles far better then when i got her.

both wheel bearings
both outer tie rod ends
both ball joints
both control arms
both halfshafts
all rotors
all brakes (not e-brake yet)
all tires
both front rims
both front swaybar bushings
upper radiator support brackets and bushings.
engine and transmission mounts
all the little rubber hangers on the exhaust

I've exhaustively gone through and looked for anything that could be loose and knocking, though I really don't think thats the cause, as the thump seems to vibrate through the floor. bit intense for something just knocking around i think. replaced the beat up fenderwell splash guards though just on the off chance that they were bouncing off the tires. Im completely at a loss here guys.

Yea the noise began before i ever put a wrench to the car. Pretty much all those pieces were replaced one at a time, with an alignment done by firestone after each piece (got the unlimited alignment package). they told me my camber is a tiny bit off on the left side, but it was within range. and yes bill, when i replaced the rear rotors and brakes i checked the ebrake. didnt look very worn and i rarely use it so i decided not to replace it.

Have you checked the sway bar end links?

Originally Posted by luckyg817

Have you checked the sway bar end links?

yea they are new too lol

Originally Posted by stocker

I think strut mounts and/or all new suspension up front should have been much earlier on the list.

i had the struts checked out by a shop since i dont know how to tell if they are bad or not short of bouncing the front end up and down and checking the rebound lol. shop said they were good. is there anyway i can check them myself that you know of?

******* it. its the strut mounts. rubber bushings are both cracked to hell, bolts moves every which way if you so much as think about leaning on the car, lol start rocking it and i cant figure out how the hell its still driveable.... plus i can grab that little metal plate on the very top of the strut mount and rotate it a quarter inch back and forth with minor effort... thank you everyone. once again you've saved the day lol.

do i really have to replace the struts along with the mounts? lol mounts look so cheap...

You don't "have" to, but struts should be replaced every 75k miles anyhow.

I just put a set of quick-struts in from RockAuto, they were a breeze to put in.