996.2 GT3 Clunk
Author
Discussion

M7NRD

Original Poster:

25 posts

162 months

Tuesday 12th April 2016
quotequote all
Afternoon All,

I'm getting a clunk from the front end (I think near side) of my 996.2 GT3. I can reliably reproduce the clunk by weaving from side to side at a medium speed (30-40 mph say) and the clunk is only audible in one of those directions (i.e. high lateral load in one direction after a similar load has just been applied in the opposite direction). There must be movement in both directions but what I'm saying is I can only hear and feel it in one. Occasionally I'll get the same clunk unexpectedly over a bump / hump but I can't reproduce it on demand that way. The clunk can be felt through the steering wheel moderately.

The car has been in to my local specialist a couple of times now to have this looked at at the same time as various other bits (service, MOT, new starter from memory). The lower control arms have been replaced on their recommendation, and for good reason if memory serves. The drop-links were replaced 3000 miles ago and the the front shocks were overhauled by JZM at the same time - both around 3 years ago. I've been assured everything else has been tightened, pushed, pulled and prodded and found to be in order. Now it has been suggested that the next step is to remove the steering rack and have it overhauled (or replaced) as apparently this is only remaining place the knock can be coming from.

Really I'm just seeking some validation that this is a reasonable next step. I would normally just go along with their recommendation but having had it in for investigation a couple of times now I'm just checking. The specialist in question is reputable as far as I know and been in the game for decades. I have used them myself for several years as have other people I know - with nothing bad to say at all.

Thanks in advance for any input.

Richard.



Porsche911R

21,146 posts

294 months

Tuesday 12th April 2016
quotequote all
Top mounts ?

Pugley

687 posts

221 months

Tuesday 12th April 2016
quotequote all
Just a hunch.

It could be stiction in the top ball mount.

When this happens the coil spring literally binds on the mount when the steering is turned. The clunk may be the spring rebounding to its correct position.

To test this, liberally lubricate the top mount ball and the area where the top of the spring rests against the mount.

If the clunk disappears then you can have a closer look at why the ball is sticking (possible wear or the bronze ball needs soaking in oil)?

Have not heard your particular "clunk" but it could be the noise of the spring rotating in the manner described????scratchchin

M7NRD

Original Poster:

25 posts

162 months

Tuesday 12th April 2016
quotequote all
Porsche911R said:
Top mounts ?
Pretty sure the top mounts have been checked, and were also sent off to JZM with the shocks when they were overhauled 3000 miles / 3 years ago. Will ask the question though when it goes back in - thanks.

nxi20

785 posts

234 months

Tuesday 12th April 2016
quotequote all
If it's still on the standard Bilstein dampers, I'd suggest the top collar on the damper body has worn. If you ask Bilstein nicely, they can put 2 in when they rebuild the damper which will increase service life considerably.

LaSource

2,642 posts

237 months

Tuesday 12th April 2016
quotequote all
All the above sound sensible places to start.

Also check the front boot tub under the polysterine boot floor for any foreign objects knocking around.

M7NRD

Original Poster:

25 posts

162 months

Tuesday 12th April 2016
quotequote all
nxi20 said:
If it's still on the standard Bilstein dampers, I'd suggest the top collar on the damper body has worn. If you ask Bilstein nicely, they can put 2 in when they rebuild the damper which will increase service life considerably.
I forgot to mention that it has KW coilovers and top mounts.

Porsche911R

21,146 posts

294 months

Tuesday 12th April 2016
quotequote all
M7NRD said:
I forgot to mention that it has KW coilovers and top mounts.
it could be any arm with a 10 year old rubber bush, or ARB bushes, steering links, upper control arms, Compression Link , ARB bush's etc etc

esp as you have had new LCA as that then moves the loads to older stuff and wears faster.

Porsche drop links are like cheese but you have had those done.

as you can see a lot to go on and a lot of bush's on the front end.


M7NRD

Original Poster:

25 posts

162 months

Tuesday 12th April 2016
quotequote all
Pugley said:
It could be stiction in the top ball mount.

When this happens the coil spring literally binds on the mount when the steering is turned. The clunk may be the spring rebounding to its correct position.
I don't think I can generate the clunk when turning the steering on the spot - I'll check though. If I can't though, wouldn't it suggest that it's not top ball mount stiction?

arcamalpha

1,113 posts

193 months

Tuesday 12th April 2016
quotequote all
Porsche911R said:
it could be any arm with a 10 year old rubber bush, or ARB bushes, steering links, upper control arms, Compression Link , ARB bush's etc etc

esp as you have had new LCA as that then moves the loads to older stuff and wears faster.

Porsche drop links are like cheese but you have had those done.

as you can see a lot to go on and a lot of bush's on the front end.

That's the rear!

Cheburator mk2

3,221 posts

228 months

Wednesday 13th April 2016
quotequote all
arcamalpha said:
That's the rear!
'nuff said indeed...


Porsche911R

21,146 posts

294 months

Wednesday 13th April 2016
quotequote all
give or take the same set of arms, it's a non issue, was just showing how many items are under a car which can wear out

Smi1er

109 posts

243 months

Wednesday 13th April 2016
quotequote all
Pugley said:
Just a hunch.

It could be stiction in the top ball mount.

When this happens the coil spring literally binds on the mount when the steering is turned. The clunk may be the spring rebounding to its correct position.

To test this, liberally lubricate the top mount ball and the area where the top of the spring rests against the mount.

If the clunk disappears then you can have a closer look at why the ball is sticking (possible wear or the bronze ball needs soaking in oil)?

Have not heard your particular "clunk" but it could be the noise of the spring rotating in the manner described????scratchchin
Thanks for posting this. I have this exact issue with mine which I was reminded of when driving into work this morning (I have a 996.2 GT3 which is actually being used now that the forum has confirmed the market is taking a dive :P).

M7NRD

Original Poster:

25 posts

162 months

Wednesday 13th April 2016
quotequote all
Thanks all for the input.

Popped in to the specialist this morning and went through all previous notes and invoices and 3 notes about wear/play in the rack have been made on the 3 times it has been in for this issue:

- wear of rack bushings
- wear of internal pinion
- internal wear on the left side

Looking at it simplistically they appreciated I've brought it in 3 times and it's still not fixed but agreed to go through everything extra carefully (including the rack itself) when disassembling it next week before sending off the rack for refurb or replacement. I'm confident of a satisfactory outcome and that they will be fair with me _if_ anything comes up that they should have spotted before so fingers crossed!

Will report back in the next week or so!