ubr911

Hi Guys, I have a Series 1 GT3 (2006 MY07). Its fine at sub normal speeds but starts to sway from side to side at speeds north of 150 kph (feels like wind buffetting). Going over 200Kph and the swaying starts to get pretty scary. It also sways in the same way under hard braking. I have the car set to normal factory settings (spoiler and suspension) and have just had the rear alignment checked.

I have been told this is normal for a GT3 but I cannot believe this, my TARGA 4S is way way more stable and is able to push on past 250kph no problem at all, its feels totally planted to the road, but the GT3 is another story!

One thing to note the GT3 is a comfort spec WITHOUT scaffolding in the back but I don't thing that would make it sway like that. Does anyone else have this issue?

Would adjusting the rear wing for more downforce fix it? Maybe tyre pressures?

cheers

993GT

Worn suspension bits, tires, alignment...about all that can be THAT wrong..

Spyerx

How many miles/km on the car? How long have you had the car? You sure its never been hit? Not normal. Check all suspension, arms, links, shocks, alignment, tires, tire pressures. Get it checked out by a shop that knows these cars.

BBMGT3

1) rear tires different wear. one may be more worn than the other
2) Toe out in the rear. Check alignment
3) Bump steer, causing toe out under load
4) Broken damper / suspension arms / bushings causing "play" in wheel. Lift car, try to rock rear tires

I had this before. Its solvable. The guy who told you its "normal"? Fire him.

runet

I had two shocks that where shot on my 996 GT3 a few years back, one front and one rear and not on the same side. The car was all over the place, hit the brakes hard from speed and the car pulled sideways.

TAI2

Worn LSD can cause unsteadiness under heavy braking.......

cunno

Start with tyre pressures, are they correct? Then as above broken or worn part plus incorrect geo could all do what your describing above.

997gt3north

totally NOT fvcking normal - I pray to god this was not someone who is working on your car that said this - if so RUN

car from the factory delivers nearly ZERO Front & Rear Lift - so should be ZERO aero effect due to speed

if you have the RS wing and a huge Angle of Attack, then without the Cup front lip you will go aero unbalanced at about 200kph - car will start to cavitate - the Cup front lip stops this from happening

if terms of side to wide wiggle under accleration, if your steering wheel is vibrating back and forth, then you likely have a front tire balance issue (may also be suspension bits at the front) - if your *** is wiggling, look to the rear bit

if you have aftermarket toe steer bits that have exposed ball joints, they may have developed play and need replaced

car 'should' be completely rock solid from 0 to 196mph (max speed) - i can only confirm up to 255kph that I have seen on the track

if it was a decel only problem then I would say the LSD is toast - but that is NOT what you are saying

you either have something loose with play in it or broken and / or your tires are severely out of balance

i would start with the tires - get them balanced - if it is still there, one of or more corners have a suspension part that needs tightened and or replaced

pmaia

I had same problem!!
Bought it 2 month ago, no accident, 20.000 Km, mint condition.

Made allignment with stock values and get much much better... But not perfect!

I also need some help with this problem!`

How can I check if shocks are ok?
I put the car in a machine that compares left and right shock. In front 1% difference but in back 7%.. ~

I have almost new tires.. Pirelli Pzero n rated but not corsa!! And I feel they are not correct balaced, because I feel some vibration between 120 and 150 Km/h.

I took the car to a guy that makes allignment to lot of racing cars... He said that under the car everything is great!

One thing is true, after allignment the car was much better... But I still feel a bit scary over 230... 250...

when I make a corner at that speed I almost donīt need to move steering wheel.. it is very very sensitive!

usctrojanGT3

Make sure you don't have slightly bent wheel/s.

oldskews4

I'm betting on two things. Worn bushings and/or alignment.

BBMGT3

due respect to your race alignment guy, but you don't check alignment under the car. If he didn't put it on levelers and check the geometry of the car then he didn't check anything, he maybe eyeballed the suspension but thats it

If alignment improved things but the car is still scary... find someone with the same car and ask them to drive your car. Also, this may sound like a stupid question, but where did they get the alignment settings from? And how confident are you that they did the work right?

pmaia

The guy that made allignment check and adjust the geometry on the machine!!! He had the stock values , So has I (from here and from OPC)

When I was talking about everything is ok under the car, was about signs of damage or use..

I am not 100% confident about the results of the machine!! For instance, donīt know when it was calibrated ...
I will go today to another allignment shop and will balance the wheels and check allignment values, so I can compare with the last ones!

But I must say that the car improved a lot.. But when I compare with the 997 TT that I have, I must say y 08 GT3.1 is much more nervous and sensitive to drive at high speeds!

993GT

what ride height? almost sounds like it's heavy bumpsteer...

pmaia

Donīt know!!!
But will bet is stock, because all the screws and bolts under the car had no signs of being used!!

From where to where should I measure!!

But I really canīt lower my car... Will have serious problem getting in the garage!