greg1234

I thought I'd check the distance between the ground and the wheel arch on my car, and found the distance to be approx 65cm all round. The left front, though, was 67cm. Is this within normal tolerances, or could it indicate something fishy, that perhaps relates to the scariness at speed....?

Tyre pressures were checked yesterday and the floor must be level or else the back would also be out...

Christer

I think you may have just found something. I am sure this would result in some pretty strange handling....

fc-racer

My car sits at 63cm all around. However, I've noticed that the car takes some time to settle down and you have to be careful when you park it not to brake hard to corner while parking. I've seen my ride heights vary as much as 1.25cm based on a slight gradient.

Your problem with instability likely comes from your tires and the comfort level you have with the car. For example, I came from a 1989 944 Turbo S, one of the best cars ever made, bar none. It was rock solid on the highway up to 285km/h and it was even more solid on the racetrack going through Turn 1 at SIR at 265km/h.

In comparison, my 911T feels like it's going to lift off on the highway. The steering goes quite light at high speeds, the car darts around in the wind and the car does not tolerate aggressive alignments, following every groove in the road.

I have found however that as the tires are wearing down, the car is becoming better which indicates to me that what I felt as instability is likely tire squirm, whether it be from the sidewall or the tread itself. Also, some lightness will be felt because of the weight distrubution of the car, you can't get around that. The new 993TT and 996TT don't have it as bad since they have the AWD drivetrain up front.

I've ordered a 3.8RS front splitter to try and help matters, but I think my car's feeling of instability comes from two areas:

1. Alignement (I'm running only 10m of toe-in up front and in the rear)
2. Sidewalls (the S-02 is a much softer sidewall tire than what Porsche originally specified for this car)

I might also have some bushing issues which I'm going to look into. My rear was very unstable before and all it took was a little toe-in to calm things down so I think the front will need the same, maybe 15m of total toe-in might do the trick.

Swap tires with a narrow body 993 owner and see if the problems go away.

fc-racer

Kevin Ross

Hello

Just a thought - I agree with the comment on ride height differences, they can vary depending on how the car 'settled' when parked... I'm not an expert but have noticed the same thing.

Also, I have found that a full petrol tank seems to make the car more stable at high speeds. Sounds crazy, I know, but it seems the extra weight in front seems to minimise the 'lightness' one experiences.

Any thoughts from the experts?

VS

Kevin,
I'm not the expert but here's an idea. A typical problem with 911s at high speeds is the aerodyinamic nose lift. Well maybe "lift" is too strong a word... Anyway, you do feel some "lightness" in the steering of the car. I guess is that's what you are referring to? If that's the case, no wonder why more fuel helps it: the fuel tank sits in the front so more weigth helps to push the nose down

JBH

The factory manual provides the following specifications for the 964 Turbo:

Front Axle
From wheel/road contact surface to outer hexagon head mounting bolt for "cross member to body"
ROW: 165mm +/- 10 mm US: 175mm +/- 10mm

Rear Axle
From wheel/road surface contact to checkpoint on control arm
From wheel/road surface contact to check surface on outside of control arm mount (body end)
ROW: 270mm +/- 10mm US: 280mm +/- 10mm

This should provide a slightly nose down profile on the car. It doesn't cost much to get the ride height set, the car cornerbalanced, and wheels aligned ($200 - $300). I can tell you from experience it has a huge impact on handling. I would almost bet it would solve your problem. Make sure you find a reputable shop (probably a race shop) that has the scales and all the tools.

Kevin: your experience confirms the necessity of having the ride height set properly. A full tank is going to put just enough weight up front to put your car in a better position. I would check your ride height too.

Let us know what happens.

Christer

I have have only owned a 964 for around 7 months now. I had some undue twitchiness at speeds of over 110mph initially. After I fitted 17" wheels and had the alignment done it is now pretty solid. Even my n/a 964 will do over 140mph and feel pretty solid. Chatty maybe,(i.e. I wouldn't want to take my hands off the wheel) but solid.

Surely a Turbo should have even better capabilities in order to cope with the extra 100 or so horses?

Greg, I think if you can get this sorted you may want to keep the car. I would be quite happy to go over 130mph with you in my car to see if you feel any difference. It maybe that you are of a nervous disposition. I will say though that the 911 is a little more fidgety at speed than say my dad's BMW 525i - I think this is called 'steering feel'.....I prefer it now, but it took some time to get used to...

Best of luck!

Christer

greg1234

Hi Christer.

Nervous.... only when it feels like the car is going to leave the road!!

I have no problems doing those speeds in other cars and bikes - and as I mentioned before I've done 170mph in my 928GTS.

Chatty, yes - the Turbo seems to pick up road imperfections that you can't even see, and reports them faithfully! Reminds me of something I once read about a car that supposedly had very communicative steering (can't remember which one):

"Not only would you feel it if you ran over a packet of crisps, you'd be able to tell which flavour they were"

JBH - you must be getting fed up with suggesting corner balancing to me! It's not that I don't think it's a good idea - I do think it's a good idea - but whenever I've mentioned it to a dealer they've either said they can't do it or they never do it these days.

Kevin Ross

JBH

I am going to get wheel balancing / ride height adjusted Tuesday next week... will let you know what it was before / after.

Thanks muchly

PS.. also going to get new $2000 stereo fitted.
Woohoo.. <img src="graemlins/jumper.gif" border="0" alt="[jumper]" />

greg1234

OK -

I've been doing some more testing on my local, er, high speed track and there is *definitely* a difference in the way the car handles on left and right hand bends at high speed. Right hand bends seem fine. Left hand bends are scary. The car just feels wrong, as if it's not all pointing in the right direction. It also feels a bit like it's trying to tuck under on left hand bends rather than corner flat. Finally, it gets extra twitchy and bouncy on left handers.. make it feel less predictable. It's almost like it takes a while to react, but then it over-reacts and starts trying to tuck under, so of course I have to correct, which makes it flip the other way and so on. I'm exaggerating slightly but that's what it feels like.

I suppose I'll have to take it in somewhere. JZ Machtech would be my first choice... but they're sp far away. I might try GT-One again.. though for some reason I get the feeling JZM would be better at suspension work.. not sure why..