Windy Water Boy

Hello all, as a new Rennlist member I've really appreciated the comments on various issues while I was doing research, and am the new owner of a lovely 2009 997.2 C2S with loads of toys.

Asking for help please with suggestions as to why the car is squirming/swaying from side to side a lot under moderate to firm acceleration. This is happening even on straight pretty even roads. I had thought it may be down to tire pressure or road camber, but even after checking pressures and running on flat 6 lane roads it is still happening. However at constant high-ish speeds there is no swaying at all.
Any suggestions gratefully received. Many thanks

RichFL

What model car and tires? Any modifications? PASM? This may sound silly, but are you certain PSM is ON?

Saaboteur

Have you looked at the wheel bearings? Check them for play. Any weird noises?

Windy Water Boy

Thanks Rich for the quick reply. It's a 997.2S on moderately worn Pirelli PZeros - front: 235/35 ZR19 87Y and rear: 295/30 ZR19 100Ys. Car has PDK, Sport Chrono (Sport, Sport Plus), PSE but not PASM suspension. Just 30k miles and full history.
When I switch the car on it always defaults to "standard" throttle response and I need to select S or S+ if I want it. I have never tried playing with the PSM button but had assumed that it was "on" as standard.
Hope that helps...?
Thanks

Windy Water Boy

Thanks Saaboteur. The car had a fairly comprehensive check as I had the Porsche warranty extended for 2 years when I bought it, and nothing was raised.
I haven't heard what I would normally describe as a wheel bearing sound (as per old tired taxis etc), but at very low speeds (walking pace) I have occasionally heard a slight faint "rotating" sound that I took to be coming from the drive shafts, but this seemed to disappear with any more speed

jem7v

Nothing is wrong with your car. It's perfectly normal. All of the 911's do that. My 997.2 turbo S does that, my uncles 991 911c4s does that, a 991 911 c2s I drove does that.

What usually helps for that not to happen, is to make sure tires are very well warmed up before slamming the throttle.

It doesn't do it when you launch the car though on the AWD models. Probably because the systems are engaged to use all 4 wheels. When you switch to sport mode with an AWD model it puts most of the torque in the rear to act like a RWD car.

CosmosC4S

Gee...you must have hit the G-spot for the car to be squirming/swaying from side to side!

RichFL

Your car sounds almost identical to mine. At start up, PSM is on automatically and Sport Mode is off. I can get my back end to slide if I accelerate quickly with the wheel turned. This is common when I'm on the track, but doesn't happen on the street unless I force it. I never have felt it during straight line acceleration on or off the track.

I don't have an answer. Worn tires, poor alignment or something wrong with the rear suspension come to mind. The latter isn't likely if it was checked prior to warranty extension.

jem7v

I think you all are maybe over interrupting and exaggerating his swaying issue. This sound like simple torque steer off launch which is EXTREMELY common with the 911s. When you floor the gas and the tires aren't warm they do a little squrriel dance.

Bruce In Philly

I have a 2009 C2S coupe and experience the same squirm. I believe it is from the soft bushings. To be blunt, Porsche has really dummed down these cars and have continually taken out performance items such as this.

BMWs are also pretty famous for squishy chassis bushings.

I don't like it as my 2000 Boxster S had more road feel and no-squirm tracking. Sorry, but we drive a fantastic GT car... it is no longer a true sports car.

Peace
Bruce in Philly

jem7v

Just call bbi for rear control arms. Problem solved. But enjoy the maintenance on a spherical joint on a car driven on the street. Can't get those things dirty.

Macster

If you are sure the tires are inflated properly if they are unidirectional tires they are mounted properly that the tires display no real signs of alignment wear issues I'm guessing the tires are worn?

These cars are quite sensitive to worn tires. My Boxster was squirming something fierce to the point I thought the suspension was wearing out. With 288K miles I figured it was about time. But the front tires were quite worn, as worn as they have ever have been. I usually run them 40K miles but this time I left then on for more miles. I don't know how many more miles but way past 40K and like I said they were worn quite a bit. Not to the wear bars but close.

Because this year was proving to be a wet winter I broke down and had new front tires installed. The rear tires have plenty of tread left. The squirming went away. With new front tires installed what a change and for the better.

Oh, the squirming was at highway speeds. At lower or higher speeds the squirming was not present.

StormRune

Do you know the age of the tires? Even if the tread is good, older tires get hard and don't stick very well. The degree of squirming you seem to be experiencing sounds greater than what I would expect. I can't say that I could report experiencing any such thing in my 2S unless I'm driving on slick pavement in cold weather with cold tires (45 degrees F or less) with my summer tires... but I see you are in Dubai so I assume you don't get that cold?

onewhippedpuppy

Absolutely. Check the date codes, I typically replace if much older than 4 years. Because Porsches aren't normally a daily driver, it's common to find them with old tires that have great tread.

Windy Water Boy

Thx for the feedback. The tires are 2 years old (and by law here they have to be less than 4 yrs old). Current winter ambient temps here are 15-25C/60-75F but up to 55C/130F summer.
Appreciate the thought about cold tires - In retrospect the worst I have felt it was a couple of days ago and the tires will have been quite cold. The rear was swaying so much that the car was hard to keep driving straight