Noise from the back

[brendel]

Hi everyone,

I am getting a loud noise on the rear when i am braking gently on a manhole or very slight pothole, always at low speed, which makes driving in town unpleasant

I wanted to know according to you which part get shot first on the back of the car? I have 85 000 miles on my C4S

I am also thinking about other parts than suspension, like engine mounts? CV joints?

Other wise on the supsension which control arms would you change first? what about suspension top bushing, could the suspension strut be shot ( seem to do the job to me)

So far I changed the cheapest thing I could .... sway bar links and sway bar bushings ( all tighten up with the right torque )

Thanks

[therock88]

Probably going to need to be a bit more descriptive on the noise and/or conditions to get help here. What does the noise sound like? What area of the rear? Just at slow speeds, or also at higher speeds? etc.

[brendel]

I would say a "clonk" located in the back, at the level of the quarter windows

I would not hear anything when driving over speedbumps, it happens just when braking gently over a small road imperfection,

The road does not need to be very bad, it can be a road joint and if I press the brake very gently: " clonk"...

The noise is relatively loud, disproportionate to the size of the road imperfection and I can hear it most of the time when I drive down a slope and breaking

My driveway has a relatively high incline and there is a difference of level between concrete slabs , going down I hear it, going up I don't...

I have it since I bought the car (15 000 miles ago) but it does get louder

I did look on both sides and tried to shake all the control arms, shake the wheel, check the CV joints for play, everythings seems very normal

I changed my brake pads and glue brand new antisqueal dampers ( cleaning the pad before) so nothing loose here, I also thought it could be the air filter box but its seems to hold tight and is mounted on elastomers...

[Loren]

The most common loose component in the rear is the swaybar mounts. The can make noise depending on wheel load and displacement.

[brendel]

Hi Loren,

I did change both bushings and links both with new bolts, threadlock and rightly torqued

Nothing changed

What about engine mounts? do they wear easily?

Thanks

[logray]

Engine mounts are fluid filled, and to check them just look and see if there is fluid coming out of them, if there is they are bad.

Did you lube the swaybar bushings?

[RFM]

The part # 99733104301 named LENKER in german, i do not know exactly how you call it in englisch, is a well known noise maker under gently braking on uneven surfaces, cobblestone, etc. The problem is that there is nothing to see or feel, but with a little play on the uniball he will make noise when braking gently.

[brendel]

Thanks for your answers,

The Say bar bushing were not lubbed, should I do that?

The "Lenker" is what I would call the control arm, I think it could be the culprit too

Thanks to all, I will buy a new pair and keep you updated ( might take a month or 2 though)

thanks again

[dphatch]

I might suggest you get a qualified mechanic to diagnose your problem before you throw more money replacing parts that may not be causing your problem. Your second post regarding this same noise suggests that you're replacing stuff without having first determined what needs to be replaced. Costly approach to automotive repair particularly on a car like a Porsche where the parts aren't cheap.

[brendel]

Quick update to all, RFM was right, 99733104301 had play in it , you can feel it when the part is removed from car

I changed them on both sides, the problem is now solved

Thanks again