Pedro, do you work on Carreras? I am getting a thunk.

I just posted this over at Rennlist but better here I think...

2009 C2S Coupe, 46K miles

This has been bugging me for about a year. I just have not had the time to look into it.

I get a clunk from my rear (the car) when I go over a sharp bump like a parking trundle or garage speed bump. I don't believe this is a classic control arm issue as it takes a sharp bump to really pop the back end up. (I replaced more than a few Porsche control arms so I think I know the sound.)

It is a deep thunk (not metallic) that sounds like it is coming from atop the engine, maybe the right/passenger side. I noted it "sounds like its coming from" but I am not really sure. My active imagination tells me the engine is lifting and dropping like a bad mount or something.

It is really bugging me lately as I am parking in a garage with those really hard, short, rubber speed bumps they bolt into concrete. They are narrow and high so my car lurches up and then I get the clunk.

Anything I can look at without a lift?

Peace
Bruce in Philly

My car's PASM lowers the suspension a bit, which might also shorten the travel. I have to take it really slow (of course) over speed bumps otherwise the right front (for some reason just there) makes a pretty nasty thunk (not thump; not clunk.) It's less susceptible to this when set to Sport, which makes sense as it stiffens the shocks.

Jack up the car, take a crowbar and lever al the major suspension members, except the drop links and Tie rod ends that you cantest by hand to see if they are loose. If nothing seems loose, bang hard on the suspension members with a rubber mallet. If something is bad, you will hear a clunk.

... the various suspension components, as noted by others, but also don't overlook the engine and tranny mounts.
The two engine mounts are easy to inspect.
You can clearly see if any one is leaking from underneath.
If leaking it won't be much, but any leakage indicates it's done.
To inspect the tranny mount you'll have go remove the tranny's under panel.
The rubber mount is exactly the same as the Boxster's front engine mount, so they suffer from the same malady.
Happy Porscheing
Pedro

Pedro Bonilla
1998 Boxster 986 - 311,000+ miles: [www.PedrosGarage.com]
PCA National Club Racing Scrutineer - PCA National HPDE Instructor - PCA Technical Committee (Boxster/Cayman)

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Racecar spelled backwards is Racecar

"Racing is life. Anything before or after is just waiting" ... Steve McQueen as Michael Delaney in "LeMans"

"If you wait, all that happens is that you get older"... Mario Andretti

"Being second is to be the first of the ones who lose" ... Ayrton Senna




Edited 1 time(s). Last edit at 01/12/2014 10:01AM by Pedro (Weston, FL). (view changes)

Didn't I read a story a long time ago that Porsche developed these special mounts using anti-freeze as a damping fluid and these were installed in a Ford 4 Cyl car due to this engine's vibration problems? I think this was a product of Porsche's consulting arm no?

Peace
Bruce in Philly

... but it's a dark greenish/bluish gel-like oily goo.
They've been using it since the 993, although I'm sure it's been reformulated a few times.
Happy Poscheing
Pedro

Pedro Bonilla
1998 Boxster 986 - 311,000+ miles: [www.PedrosGarage.com]
PCA National Club Racing Scrutineer - PCA National HPDE Instructor - PCA Technical Committee (Boxster/Cayman)

---

Racecar spelled backwards is Racecar

"Racing is life. Anything before or after is just waiting" ... Steve McQueen as Michael Delaney in "LeMans"

"If you wait, all that happens is that you get older"... Mario Andretti

"Being second is to be the first of the ones who lose" ... Ayrton Senna




Edited 1 time(s). Last edit at 01/12/2014 12:22PM by Pedro (Weston, FL). (view changes)

Delphi was spun off from GM in I think 1999. The core technology was used in Cadilac where the ferous fluid in shocks could change their viscosity by applying current. This is now developed and used by Porsche in their active engine mounts. Wow, what goes around.....

Dephi Porsche News Blog

I am 99% sure I read that Porsche Consulting developed mounts that contained antifreeze for Ford... I just can't find the article.

Thanx Pedro, I will check under there this week. I will be staying at a friend's house where she has a grease pit. I changed my plugs there. Grease pits are not high tech but darn valuable.

Peace
Bruce in Philly



Edited 1 time(s). Last edit at 01/12/2014 06:07PM by Bruce In Philly (2000 S Boxster, now '09 C2S). (view changes)

Allt he magneto-rheologic dampers are Delphi (aka AC-Delco, aka DEtroit ELectric COmpany*), which has been (partly? Mostly? all?) bought back by GM to prevent their tech source from going under. Cash provided as part of bankruptcy negotiations.

G

* AC = Andre Champion, who lost the trademark use of his first spark plug company

Grant

gee-lenahan-at-gee-mail-dot-com