Porsche Enthusiasts Club Forum

Annoying Knocking Noise From the Nearside Rear.


2003 Boxster S. I asked the mechanics to investigate a knocking noise, they road tested it with me and it was clear. They have told me it is nothing mechanical. All bushes, wish bones, suspension elements are all sound.
I think they are not correct.

Here are the symptoms:
It is coming from the nearside rear of the car.
It only happens over bumps.
The noise is kind of a hollow clonking noise that only happen when i am going over slightly bumpy roads.

You will have probably got excited to see a reply...but I am sad to say it doesnt sound like what I thought when I started to read your post...My S developed a knock after only a week of ownership..!! and it turned out it was the wheels ..there is literally about a few millimeters between the alloy and the suspension strut and the weight for the wheel balancing was catching and causing the most horendous knocking noise....I had had new tyers put on and they had used those hideous hammer on weights and not stick on....so changign the weights to stick on resolved it striahgt away....but as I say this is not it as it would be there all the time....however I thought I would mention it so you can eliminate the wheels......
T
;o)

I am rubbish at mechanical stuff..its not a loose exhaust mount is it?? or something to do with the exhaust hitting the underside when jolted?

My 1998 Boxster developed the same noise some months ago, I was told by many Porsche experts the problem was with the drop links. I have had all four drop links replaced and the clunk is still there. I have had all the suspension checked and as with your car all is OK.
The mystery continues but I am still searching.

Most likely the control arm centre bush going weak.

We see it quite often where the bush becomes weak, allows the bush to knock in the connecting fork that clamps it... Many places miss this because they are expecting a bad bush to be cracked or split.

Another alternative could be the engine/transmission mounts, not as common though, as are rear strut top bearings, but possible all the same.

Someone used to Boxsters should be able to find it in no time.