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jons997
Newbie
Joined: 21 Nov 2019
Posts: 9
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 Posted: Thu Nov 21, 2019 4:58 pm Post subject: 997.2 C4S front end knocking noise over speed bumps
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Hi all,
I recently purchased a lovely 2009 997.2 C4S manual. It has 49k miles full service history and drives very well (as far as I know!).
The only thing I am a little worried about is that when I go over a speed bump there seems to be a bit of a clanging sound both going up and down over the bump... sound is light and metalic. It drives very well but I am concerned this may be the sign of something to come if I dont deal with it now!
I tried pushing down on the wheel arches to test the bounce.. found there was no bounce.. but also that my wheel arches seemed a little loose.. both of them.. The garage that sold me the car said they had recently resprayed the front end so this could possibly be why..
Has anyone got any thoughts or experiences?
Thanks all!
Jon.
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GMG
Nürburgring
Joined: 07 Jan 2018
Posts: 463
Location: Devon
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| Posted: Thu Nov 21, 2019 5:38 pm Post subject:
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Your wheel arches are loose? You are going to need to provide a more detailed and accurate description if you want a similar response...
You know what they say " crap in, crap out !"
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Magic919
Barcelona
Joined: 05 Jun 2013
Posts: 1283
Location: Berkshire
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| Posted: Thu Nov 21, 2019 6:02 pm Post subject:
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You’ll be replacing various bits of suspension from now onwards. Best way is to attach some chassis ears and diagnose. A decent indie will do that.
_________________
997.2 C4S PDK
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love154
Trainee
Joined: 18 Dec 2018
Posts: 91
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| Posted: Thu Nov 21, 2019 6:13 pm Post subject:
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i would say top mounts
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jons997
Newbie
Joined: 21 Nov 2019
Posts: 9
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| Posted: Thu Nov 21, 2019 6:13 pm Post subject:
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Thanks fella's, re the 'wheel arches', I am talking about the bodywork over the wheel. When I put a little pressure down to create some suspension travel I found the bodywork 'moved'... so doesnt seem fixed solidly.. is this normal?
But yes, thanks for the terminology 'chassis ears', I will take the car back to the garage I bought it from and mention this.
Also re replacing parts from now on.. I thought the noise may be caused by a perishable rubber part on the suspension or some rod in this area.
As you might tell, I am not very aware of what is going on or how to describe this to the dealer who gave me a 3 month warranty I would like to use!
thanks again!
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jons997
Newbie
Joined: 21 Nov 2019
Posts: 9
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| Posted: Thu Nov 21, 2019 6:15 pm Post subject:
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will get them to check the top mounts too!
thanks
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Magic919
Barcelona
Joined: 05 Jun 2013
Posts: 1283
Location: Berkshire
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| Posted: Thu Nov 21, 2019 7:30 pm Post subject:
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If you mean the front wings, then they should be pretty firm.
_________________
997.2 C4S PDK
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Lee997
Silverstone
Joined: 04 Apr 2019
Posts: 113
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| Posted: Thu Nov 21, 2019 8:56 pm Post subject:
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There’s a lot of components to the front end. Had a similar experience recently, after getting the car back from Porsche Colchester’s bodyworks company after some paint correction work and full geometry setup the car quickly developed a knocking from front end (more noticeable on slow speed bumps), unable to get a messages left responded to I ran it into my indi and while stood next to him we both found a steering track rod locking nut loose and wound up the thread (clearly they’d adjusted but failed to lock it off after). This I and my indi believe was responsible. It went back in to the same place as the paintwork repair wasn’t acceptable, while there they agreed to replace a suspension link after they’d got porsche to do a diagnostics and come up with the bottom link being at fault with an advisory for myself to get front left shock replaced !
Having lost confidence in this mob I took it to my indi and asked them to replace both front shocks, after which the knock was still evident!
My indi spent some time checking everything and was about to give up and finally discovered the steering rack was leaking oil inside the rubber gussets and had excess wear ( no doubt exacerbated by leaving the lock nut undone)!
It’s taken 3 months to get Porsche’s bodyworks centre to come back with an answer, only to further insult me by claiming they quoted me for a steering rack ( which they didn’t, further more I have a copy of Porsche’s inspection stating the steering rack was ok)! They offered me £250.??
Moral of the story, and in answer to your question, there are a number of components that could be to blame, take it to a decent indi !
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jons997
Newbie
Joined: 21 Nov 2019
Posts: 9
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| Posted: Fri Nov 22, 2019 9:43 am Post subject:
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That sounds like a nightmare! did you feel an issue with the steering? or just the knocking sound was the tell?
This (cold) morning one my way to work the knock was still evident.. quite a light metallic sound and I think more on the left than the right but not sure. I noticed though that I pushed it a little in 2nd to about 3k revs and lifted and it made the same noise but much louder and definitely to the left but quite high it sounded.. like it was behind the glove compartment... still trying to visualise the location... then I tried the car with PASM in an area where there were few bumps left and the car had warmed up but the knock seemed to have gone...
could it be the cold weather? could it be the PASM?
I suppose the simple test is to warm it up and do the same run and see.. or try PASM first thing in the morning and see..
the knock when lifting was very concerning... couldnt manage to get it to do it again though..
thanks again all for your comments!
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MaxA
Albert Park
Joined: 11 Oct 2015
Posts: 1668
Location: Helsinki
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| Posted: Fri Nov 22, 2019 2:47 pm Post subject:
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Obviously the car needs to be inspected and the knock diagnosed, as it could be a multitude of sins, but from the sounds of it (so to say) it could be a drop link bush or anti roll bar bush which has perished - if it's on the passenger side, as that side tends to hit more drain covers (if not potholes). Otherwise, you need to check all the joints and bushes. But the one that knocks over bumps is - in my experience - the drop link bushes or anti roll bar bushes.
_________________
997.2 Carrera4S: white over blue, driven and tracked, seldom clean.
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jons997
Newbie
Joined: 21 Nov 2019
Posts: 9
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| Posted: Fri Nov 22, 2019 3:15 pm Post subject:
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Thanks MaxA!
I will mention those things when I take the car in.
I have had a play this afternoon and when the car is warmed up there seems to be less noise... much more evident over the first few bumps in a morning!
many thanks all,
Jon.
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Robertb
Dijon
Joined: 01 Sep 2003
Posts: 7313
Location: South Oxfordshire
2002 Porsche 996 Carrera 4S
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| Posted: Fri Nov 22, 2019 3:23 pm Post subject:
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The bigger question is the front wings... they should be rigidly fixed to the body. If they’re not then they have been replaced, and possibly refitted wrong. You would not remove them for paintwork unless the car has needed panels replacing.
I would recommend a proper inspection in case the knocking noise is related to unrecorded post-accident work that the car has had. 
_________________
"911- the guilt-free supercar"
Current: 2003 C4S Coupe, seal/black
Ex: '02 C4S Coupe, '96 993 Targa, '88 Carrera Sport Coupe
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jons997
Newbie
Joined: 21 Nov 2019
Posts: 9
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| Posted: Fri Nov 22, 2019 3:36 pm Post subject:
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Thanks Robert, A very useful thing happened this morning that.. I found the old V5 certificate with the previous owners name and address, so I wrote him a letter (old school) and he very kindly wrote back via email this morning stating that he was surprised to hear of the knocking noise. He had owned the car for the last 4 years and the only knocking noise was resolved by finding a loose battery! (thank you previous owner if you are reading) I know the garage I bought the car from had the front end resprayed in the mean time and hence the loose wings... although I also would not have expected the wings to have been loosened/removed for the paint...
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Robert SausageTrousers
Monza
Joined: 02 Apr 2018
Posts: 237
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| Posted: Fri Nov 22, 2019 3:37 pm Post subject:
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I would agree with RobertB, the front wings definitely need more investigation.
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911rpd
Newbie
Joined: 29 May 2018
Posts: 21
Location: Surrey
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| Posted: Fri Nov 22, 2019 5:18 pm Post subject:
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does it sound like two snooker or pool balls been hit together?
best to find a small water drain or a kerb that you can roll up and down on slowly to hear it more clearly - the guys did this at centre gravity and then I really noticed it, I think it turned out to be the diagonal arms but at the time I also had other parts replaced too. c£90 a side.
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jons997
Newbie
Joined: 21 Nov 2019
Posts: 9
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| Posted: Mon Nov 25, 2019 12:13 pm Post subject:
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This morning was a warmer morning than last week.... There was no noise..
I cant imagine the car is self healing, but I can imagine that last week it was cold enough for some metal work to have shrunk a bit to make something loose?... or oil in some joints to be a little cold...?
Was perfect this morning though!
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Monkeynutz
Nürburgring
Joined: 05 Oct 2016
Posts: 470
Location: Peterborough
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| Posted: Wed Nov 27, 2019 8:53 pm Post subject:
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I was barely aware of a slight knock/clank on my the front end of my car but it was pointed out to me by the guys at Center Gravity. They knew what it was instantly, N/S front diagonal arm. Got both done as I was in for a full geo set up. On first inspection it looked like the rubbers were fine and didn't show signs of excessive wear but the fault was demonstrated to me once the old one was removed from the car. 2010 C4S @ 43k miles. Just some info to add/dismiss from your list.
_________________
997.2 C4S
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jons997
Newbie
Joined: 21 Nov 2019
Posts: 9
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| Posted: Thu Nov 28, 2019 2:55 pm Post subject:
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| Monkeynutz wrote: | | I was barely aware of a slight knock/clank on my the front end of my car but it was pointed out to me by the guys at Center Gravity. They knew what it was instantly, N/S front diagonal arm. Got both done as I was in for a full geo set up. On first inspection it looked like the rubbers were fine and didn't show signs of excessive wear but the fault was demonstrated to me once the old one was removed from the car. 2010 C4S @ 43k miles. Just some info to add/dismiss from your list. |
Thanks and yes I think this will help as it does sound similar. May I ask what you gained from the full geo set up? I like the thought os someone just going round the car and checking for anything that might cause a potential future breakage..
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FZP
Estoril
Joined: 18 Jan 2015
Posts: 3872
Location: Cheshire
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| Posted: Thu Nov 28, 2019 3:10 pm Post subject:
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1. Body work should not move unless it's the rear spoiler
2. If you drive the car on a really bumpy roads and the knock sounds like it's coming from the front/middle third of the car, coffin arms
3. If it's coming from the outer third of the front of the car, then it could be drop links/ track rod ends/eye.
Not a big deal,(excluding the bodywork issue) as you're now in the window of replacing these consumables.
Good luck with the remediation
_________________
997.2 Carrera 2S GT Silver/Cocoa.
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jons997
Newbie
Joined: 21 Nov 2019
Posts: 9
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| Posted: Thu Nov 28, 2019 4:27 pm Post subject:
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| FZP wrote: | 1. Body work should not move unless it's the rear spoiler
2. If you drive the car on a really bumpy roads and the knock sounds like it's coming from the front/middle third of the car, coffin arms
3. If it's coming from the outer third of the front of the car, then it could be drop links/ track rod ends/eye.
Not a big deal,(excluding the bodywork issue) as you're now in the window of replacing these consumables.
Good luck with the remediation |
Thanks for that! I think the sound is very close to the N/S wheel so probably in '3.' from your options. thanks!
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