Drive Train Lash

[Mijostyn]

I picked up a 6 speed 2006 C4S Aerokit last June with 6100 miles on it. I noticed right away a "clunk" in the seat of my pants with rapid transitions on and off the accelerator. This gets much worse in Sport mode (more aggressive accelerator programming). The dealer says it is normal. None of my previous 911s did this. If I drive real smooth I can avoid it. I drove a brand new 991 7 speed recently and it has the same exact maldady! Anyone with any ideas???

[Loren]

Check for loose rear swaybar mounts - fairly common on all model years.

[logray]

Broken or weak motor/trans mounts can contribute as well.

If you drive it hard/on a track semi solid mounts may help.

Also damper control contributes... I notice the effect you describe more when my PSS10's are on #1 versus when they cranked all the way up to 10 (an 11 setting would be good).

[Mijostyn]

Hi Loren,

A local Porsche specialist thought the same so, for short money I replaced both rear sway bar links...no change :-(

Hi ,Logray

Both engine mounts and the tranny mount are in fine shape. I never go to the track, but every day is a track day, you know what I mean ;-}

I'm pretty sure the problem lies in the transaxle. Although some people have incriminated the dual mass flywheel. A brand new 991S 7 speed does EXACTLY the same thing. Also drove a 991S PDK and it was fine as far as PDKs go. I will never buy one. Just not sporting, the free wheeling business is plain stupid, its another 100 LB where you least need it, and my right arm will feel neglected.

[brendel]

I am going through the same story

My differential is new as changed with the tiptronic under guarantee

My sway bar links and bushes are new

The transaxle ( I guess you mean the main cardan shaft between rear and front), has been replaced by Porsche without asking, as they have seen that the rubber spacer was worn,

After all that the noise is still there

I tend to think that most people don't care that is why it is seldomly reported

I also heard the dual mass flywheel story, and that 1 car out of 5 does this without known reason

I will be changing the control arms ( not the coffin one the other big ones ) on the back as I get some clunk when gently braking, if there is some change I will let you know

now I don't have my car, as I got the nasty cylinder scoring and Porsche is changing the engine under guarantee ( an engine in 85 000 miles... no comments), I asked them to check the rear CV joints also

[Mijostyn]

I also have a 2006 C4S but mine is a manual. Not sure if the Tiptronic uses the same differential or not. Does the differential run on automatic fluid or does it get it's own gear oil? I am going to run a little experiment with different gear oils and will post the results.

I would not do anything else to your car. In your case I think there is too much water under the bridge. There is always collateral damage with any large job on these cars and you have had several. I have had two 911s that developed issues that could not be diagnosed or were fatal flaws. I traded them in. You are obviously unhappy with that car. You need to get one that puts a smile on your face every time you get in it not grief. All you are going to do by changing parts is make things worse.

[brendel]

You are reading in mind, though I still have a smile on my face despite the bad stories, I cannot get to the idea of driving something else, you know "cars with the engine in the wrong place", the front...

I will see how it goes, maybe I make friends again with my C4S with a new engine

[Mijostyn]

Absolutely, I would never suggest any car that does not have the engine hanging out over the rear axle. Can't get your golf bag in there ;-) The price we pay is having to live with personality flaws. We are not driving cars that do their best to offer a quiet serene experience, isolating you from everything. In a 911 you are hard wired to just about everything, the road and the machine. An Audi may have just as much drive train lash as my 911, you just can't hear or feel it or anything else for that mater. So, when you notice something that you think may represent a significant issue tread lightly. First have someone who knows these cars and drives a bunch of them check your's out. I have one tech I always use at my dealer who I trust as much as anyone, who I have a great relationship with. If he tells me the issue is normal for these cars I believe him. With this lash I was worried that my tranny would fall out. He says no. If there is something minimalist I can do to improve the issue I try it like playing around with different gear oils. Ripping your transmission apart chasing ghosts is the last thing you want to do. With a new car this is easy. You have a long warrantee to fall back on. A used car is obviously more difficult. I personally would never get a used car that was not certified by Porsche. For a two year warrantee it is short money. In the end you have to decide whether or not you will keep the car. A car like your's I would get rid of. A well mannered car that is endearing I might keep but, you still have to be ready, willing and able to pour $6,000 dollars into the car in a moment's notice. And, that is for a water cooled car. I believe an engine rebuild in an air cooled car is something like $15,000!