Rear Suspension Noise

[ivanuf]

I am obsessive with my car noises. I have searched and read all Forum posts on noises and I have followed all TSBs on noises. And my 1999 C2 is almost as silent as it can be. The last noise (for now) that I can't put my finger on is a tricky one and just wondering if someone else has encountered it. I narrowed it down to this:

It comes from the back of the car. It sounds like a "clunk" or loose part from (the bottom of the car not the roof) but it only happens when I hit irregularities or potholes on the roadway under breaking. If I pass over the same spot w/o braking I do not get the noise. It is pretty loud and sounds like something is loose. Under acceleration it disappears. When the weight of the engine is lifted (under breaking) and I hit potholes it makes the noise.

Parts I have changed of the rear suspension: ( I have a 4 post and a 2 post lift on the shop)

(2) Rear Sway Bar Links

(2) Shocks and top mounts

I torque all suspension bolts under car (including sway bar supports)

(2)Engine mounts

I got a steel bar and verified upper and lower control arms they have no play.

I was going to order the control arms, but to me they are not the problem. They have little play and the rubber looks in good condition from visual inspection.

Edited May 18, 2007 by ivanuf

[RFM]

If it happens only under braking there is 99% chance that the control arms ( the longerons with the uni ball fixation ) are used. Thy are very difficult to check for play.

[GOB]

I was going to tell you that it sounded like droplinks (swaybar links?) and if you have replaced those, then its a tough one to diagnose. Muffler mounts?

[ivanuf]

What control arm(s) should I replace first. Upper (2) or lower??

The car has 75,000 miles and the roads here are rough.

Edited May 18, 2007 by ivanuf

[ivanuf]

I will order the (2) upper control arms and the lower control arm. I will follow up after the installation and post the results.

[Kel]

I have 98 Carrera C2- 36k miles - maybe similar noise - and have been unable to find it. Mine occurs on sharp bumps when wheel is sharply pushed up and perhaps back. I have checked whether its engine lid loose or spoiler etc - no. The service shop report nothing wrong with left rear shock and can not find anything wrong with the rear control arms that have the ball joint on them although they said these are difficult to check for wear in the shop. All other connections/links report OK.

Mine sounds like a "pop", a bit like a bunch of wooden floor boards in unison going up and then making sound on landing. Vey odd. I'll be interested in this one.

The front castor arms were replaced recently - they had a different rattle noise.

Also I am not sure whether I am getting a bit of rear end steer in a straight line.

[evansaero]

Airbox

[ivanuf]

I am still waiting for the control arms, I will post results after the instalation.

[ivanuf]

I finally replaced the (2) upper control arms and the lower control arm on the rear of the car.

I am glad to report that all rattle noises under breaking are gone. Upon close inspection the lower

control arm ( the longerons with the uni ball fixation ) were the cause. On the end of the ball fixation the cover

rubber looked in excelent condition but inside they were damage. The metal sleeve on the center was moving to the

point of making metal-to-metal contact with the arm. The only way to diagnose this is to remove the arm and pull

the interior metal sleve, it should not move.