So this is kind of hard to explain because I am hearing a noise coming from the rear of my car and I do not know what could be causing it because really it could be anything, I am guessing it is something to do with my suspension. To start I have eibach springs and OEM struts on a 03 cl-s6. the other day i was driving on the high way (~75mgh) and when I stopped to get gas I started to hear a strange knocking noise in the rear. When I hit even the smallest bump in the road or even drive slow I am hearing the knocking noise and it sounds like something popping, I also hear a squeaking sound like something is scrapping my rotor. It almost sounds like my struts are loose or bottoming out or blown but I checked them today and they both felt fine. I also checked all of the bushing in the back and they all looked good, just a little dry rotted. If anyone has any idea of what could be causing this please shoot me in the right direction to diagnose it.

 

So you inspected the joints, boots and sway bar bushings already?

 

Yes I just did a simple inspection and looked at everything and tried to see if anything was shaking to make the popping noise.

 

Anyone else have an idea of what could be causing this knocking noise? Its driving me crazy because i cant figure it out!

 

It could be a lot of things: end links, bushings, bad shock, etc. You will have to get it inspected/diagnosed.

 

OK im getting the 105K tune up very soon I will have them inspect it then. Hopefully they don't charge me too much... Also should have them install XS headers which im super excited about!
Thanks everyone!

 

I haven't had the chance to Inspect everything yet. but now I am hearing a squeaking noise in the rear end when I drive slow.

 

Sway bar bushings, this car is notorious for sway bar bushings, and it may sound like its coming from the back, but I bet you it is probably your front bushings, if you can't change them out right away, a small dab of lithium grease will hold you over till you can change them.

 

check sway bar end links and bushings had the same "clunking/knocking" sound from mine too. I took it to a shop and had moogs end links put in all I can say is it stopped that annoying sound

 

matt, was the sound you heard sound like it was coming from lower on the car near the wheel well or did the sound come from higher up near the top hat / rear speaker area of the car?

 

it was more down by the wheel well for sure. but the noise would travel upward towards the speakers after I got the end links fixed there hasn't been any "clunking" since then.