Help My 911 is UNSTABLE!

[Chri4S]

What do you make of this?

I am a 996 newbe, having just got a 4S a few months ago.

At first I thought the car's limits were not that high, now I think there is something wrong.

I notice it in faster sweeping bends. In mid corner I have had what feels like the brakes coming on and the car takes a bit of a twitch. I cant be sure if its the PSM operating as its unnerving and I am looking at the road (and where the edge of it is) and not the dash. The car really doesnt feel that stable above 55 in a sweeping bend like the ones off slip roads etc.

Now I wonder if there is something serious amiss with the transmission. There are no unusual noises, tyres are ok, no warning lights and no knocks as if it was a shock absorber.

Any thoughts from you guys with much superior experience of a 996?

Just read my warranty booklet and thankfully all the transmission stuff is coevered except the clutch. Time to book it in I think.

[boony]

Hi

I think you definately need to have it looked at.

I've had my 996TT less than two months so I'm no veteran but it in my experience it certainly shouldn't feel like you describe. Mine feels amazing through sweeping corners - totally confidence inspiring.

Previously I had a Mitsubishi Evo 8, and would say the 996 handles better than that did - even on bumpy B roads.

First step may be to get the geometry checked by a specialist. I've read that can dramatically alter the handling characteristics for the worse if it's all to pot.

Hope you get it sorted, keep us updated.

Cheers,
Boon

[melv]

"First step may be to get the geometry checked by a specialist."

Agreed!! Second crucial step. If u r local, try GT-One at Chertsey -01932 569911/944.

First is to check you have matching tyre makes and N ratings.....

Took a pals 964 C4 out a few years ago with same reported problem -felt distinctly unstable down Egham by-pass -sure enough, mismatched tyres....

Rgds
Mel

Edited by melv on Monday 18th June 08:01

[Erik997]

Definitely sounds wrong.

Check all your tyre pressures are ok and then get a full geo check done.

[Chri4S]

Thanks for ideas so far chaps.

I am surprised the geometry can have such an effect, will investigate.

[bd02]

I had something very similar in a BMW on 18" wheels - they were VERY sensitive to incorrect pressures and as soon as one of the front tyres became over 5psi down it would crab round corners with the traction control cutting in. Check your pressures!

[anonymous-user]

Chri4S said:

I am surprised the geometry can have such an effect, will investigate.

???
911's very sensitive to setup.
i wonder how many are running round with the owners oblivious to how good they could be?

[Erik997]

Definitely sounds wrong.

Check all your tyre pressures are ok and then get a full geo check done.

[nbetts]

Chri4S said:

Thanks for ideas so far chaps.

I am surprised the geometry can have such an effect, will investigate.

You will not believe how much it affects the car if the geometry is out. Reading PH you might start to think that all the Porsche drivers have super sensory perception, with the ability to notice whether a tyre is under-inflated by .5 psi... and you would be right... ... but when it comes to the feel/handling of a 911 they are very very sensitive to the 4-wheel geometry setup. I had a 997 S that was very unstable at speed so I took it in to be checked, the rear left wheel was found to be out by about 30' or half a degree... adjustment was done... car was perfect.

Get it checked. Good Luck.

[Erik997]

nbetts said:

Chri4S said:

Thanks for ideas so far chaps.

I am surprised the geometry can have such an effect, will investigate.

You will not believe how much it affects the car if the geometry is out. Reading PH you might start to think that all the Porsche drivers have super sensory perception, with the ability to notice whether a tyre is under-inflated by .5 psi... and you would be right... ... but when it comes to the feel/handling of a 911 they are very very sensitive to the 4-wheel geometry setup. I had a 997 S that was very unstable at speed so I took it in to be checked, the rear left wheel was found to be out by about 30' or half a degree... adjustment was done... car was perfect.

Get it checked. Good Luck.

Had the geo done on my 997 a while back. Car came back feeling totally different and a lot more stable.

[Chri4S]

Don't these jobs just escalate!

I was going to get the geometry checked today but I am getting ready for new front tyres which would affect the geometry, seems pointless having to get it checked again in a few weeks time.

Tyres now ordered. But I was going to get the wheels refurbished when the tyres were due.

So, wheels refurbished Wed/Thu, put new tyres on, geometry checked Friday. Have fun Saturday in super handling car.

Sounds like one of those best laid plans destined to fail. Lets hope for the best.

Thanks for the advice.

[TOENHEEL]

bd02 said:

I had something very similar in a BMW on 18" wheels - they were VERY sensitive to incorrect pressures and as soon as one of the front tyres became over 5psi down it would crab round corners with the traction control cutting in. Check your pressures!

I had the same experience with a e46 convertible..i remember being very dissapointed with the handling.

[Dr S]

Chri4S said:

Don't these jobs just escalate!

Let's just hope you get your geo checked before you need to start on a complete rebuild of your car...

[Chri4S]

Well, got my wheels refurbished, new tyres fitted to the front and then got the geometry checked.

Looks like you guys were right enough.

The alignment was pretty poor, the rear expecially was toed out which would explain its behaviour. The front has been tweeked as well. CLCM in Edinburgh were most efficient, 45 mins all done £47.

Still early to say if it has cured the handling problem but initial feeling is it seems happier on the road.

Thanks again for the advice.

[johnmaddox]

That seems very cheap for a porsche set up. If it sorts it out then that is the bargain of the year.