997/996 GT3 dynamics

[braddo]

Riding on the coat-tails of a thread like this:
https://www.pistonheads.com/gassing/topic.asp?h=0&...

In the interests of perhaps more threads about driving and dynamic enjoyment, and fewer about the colour and style of the thread holding seats and dashboards together...

I thought it might be interesting to start a thread where people can talk about how the pre-991 GT3 cars make people feel - the kinds of handling traits they feel, or which they learn over time; how a GT3 feels the first time people drive one; how people might have to adapt driving styles compared to previous experiences in other cars or adapting to different setups of the very same car etc. How the steering feels through one's fingers. How that fantastic noise is coming from behind me rather than in front.

[braddo]

And so some bits of my experience after a few years of having a 997.1 GT3.

Understeer - having grown up hearing about 'lethal' lift-off oversteer of air-cooled 911s, I was very reticent about the idea of trail braking in a 911. I knew it from having an Elise but if it wasn't for reading Steve Rance's posts on here I would probably still be wondering how to make a GT3 quicker than a MX5 around a track! Even a little bit of trail on the road makes a positive difference, as cmoose mentions when he took v8ksn's GT3 for a spin.

On track however, the heaviest of trail braking into slow corners can't quite seem to quell the understeer. Softening the front ARB made a big difference for a lot of corners but ultimately, the understeer is still there, right up until the car does a slow pirouette... Is this the PASM effect?

Brakes - stock brakes seem to make a rumbling noise whenever you really press the pedal. RS29 Pagid pads are bloody amazing (and don't make that rumble). Braking on track days hard enough to feel a bit of ABS pulse and there isn't the slightest hint of smelly brakes after a session.

But is the ABS getting triggered because the diff isn't locking properly (thus the rear axle is unstable and triggering ABS)?

Drilled brake discs are annoying. At least once every track day I have to remove pad material from the holes to preserve fade resistance. I do it with a bit of metal coat hanger.

Bumpy roads - on bumpy B roads in France, the ride was jiggly until you simply went fast enough. On the standard PASM setting I thought the car coped ridiculously well with bumpy little deserted country roads as long you're doing more than the speed limit.

[braddo]

D.no said:

How do you have the rear ARB set up?
Tyres?
Geo?

When I bought the car the ARBs were both on full stiff. The one change has been to soften the front bar to half-way (there are 5 holes I think). It really made a difference to how the front keys into the road, say on just a trailing throttle into a medium speed corner, whereas on full stiff it felt like you'd always need to be on the brakes a bit to get the nose to grip.

Tyres were originally road P-zero pirellis - they really don't have much grip but not sure it's in a nice way. Have been on Cup 2s for a while.

Geo is due a look - just factory settings I think. So much of my car's mileage is on motorway that I don't want to go aggressive, i.e. driving out of London to and from country roads, track days, family day trips etc... Plus a couple of continental trips).

One handling trait I have found intriguing - discovered at Coppice corner at Donington - being a long corner it felt like you're stuck with some understeer for a while on steady throttle, until you can get to the corner exit phase. I started getting braver and eventually found that full throttle could be applied way earlier and instead of increasing understeer, it killed the understeer! But only on full throttle.

It doesn't feel like a drift or a transition to oversteer, but it seemed to pivot the car slightly inwards enough that it puts the car on the line you want. It's how I imagine rear wheel steer might feel. It made me wonder if there is an element of passive RWS in the suspension. Or that my suspension is fked. Whatever it is I like it!

[braddo]

evodarren said:

I I tried the DSC box. It did seem to soften the suspension a small bit but wasn't to impressed. I had the car set up at Centre Gravity before I fitted the box and the car felt great. To me it fely like I could feel what the car was doing better than with the box.

Interesting. I wonder how easy it is (for the DSC manufacturer) to program the module to simply have a single setting. So instead of the PASM damper stiffness being range 1 and range 2, the choice was simply stiffness 1 and stiffness 2. It would make them 2-stage passive dampers. It would be interesting to see how that might make the behaviour of the car more predictable.

[braddo]

evodarren said:

My understanding from what some people have told me is the dsc box works better with regular 997 and turbo. Spring rates on Gt3 are quite a bit firmer and it’s hard to make the suspension ride soft over bumpier roads.

The GT3 solution to softening the ride over bumps is just to drive faster.

[braddo]

GT03ROB said:

... great stuff...

That reminds me that being a passenger in a guards red 996.2 GT3 being spanked and drifted around Snetterton was my first experience of a GT3. It was eye-opening. And nauseating by the end...

And my wife was regretting the lack of a sports bra in my car last weekend.

[braddo]

r4_rick said:

.... I don’t want to stray from the point of your thread!

Don't worry, your post is exactly what the thread is about. It's great to read these stories of how these cars feel 'right' almost instantly to some people when they get behind the wheel for the first time.

[braddo]

I had a great early morning drive yesterday. Car got a bit dirty though...



Unfortunately I encountered some roadkill on the motorway that couldn't be avoided and I had to drive over it. I think it was a badger... I found this when I got home.



The front brake duct and the mudflap thing in front of the rear wheel have also been dislodged so I'll have to see if they're broken.

[braddo]

MDL111 said:

back to my favourite topic - how stupid is it to run a 996 Cup on road tyres…. I just don't want to have to (can't) buy/store an SUV and a trailer. Also I'd rather be very uncomfortable on my way to a track than driven a bloody SUV with a trailer ….

Have spoken to a shop and they think it is still possible to road reg one (even if they do not recommend it)

I'll take a stab and say a bit less camber and toe than a full race setup, plus an extra seat cushion and some earplugs for the road journeys and you're good to go.

Of course, you would want to watch the Top Gear episode where James May is in an Aston race car in Provence before you think about a Cup car for longer trips!

[braddo]

lemmingjames said:

Just going off track a moment but has anyone else noticed that at circa 10mph, 2nd gear, if you lift your foot of the accelerator, the car maintains its speed without slowing down/stalling?!?

Is that around idle speed? The e-throttle cars have a bit of anti-stall which will add a little throttle if the ECU thinks the car will stall. I notice it kick in when when I've pressed the throttle too little when taking off gently.

Which leads to my main little gripe with my 997.1, which is that I wish it simply had a perfectly linear throttle pedal action like a cable-throttle car. There's a little dead zone at the beginning of travel which does nothing or is slow to react; it's as if the ECU is deciding whether you have pressed the throttle accidentally and whether you deserve a bit of throttle.

After years of having cars with instant throttle response (e.g. 1cm of travel is plenty to move from rest; a literal stab of the throttle with a heel is enough for consistent H&T) it surprises me to realise I am still having to think about how I use the throttle in the GT3 after, oh, nearly 5 years and 20,000 miles.

[braddo]

Slippydiff said:

... (and a lone Escort Cosworth)



...

I hate to be a pedant but I think there are 2 Cossies in that photo (3rd and 4th cars past yours).

That must have been crushing about the 22B when it happened. Still, the 964RS outcome was a good one.

[braddo]

LaSource said:

...

We also did a night session at Portimao and that was very very cool - First time I've driven at night at speed on a circuit with no floodlights!! You really do not blink! Plus with standard lights (not dynamic lights and not rally car like multi beams), you can't actually see the apex until you are on top of it, so braking and turning points are totally different - a bit like the rain you are driving on more instinct and feel than actual vision!

I wonder if it would be the one time it is acceptable to have fog lights turned on in clear conditions.

[braddo]

A bit of thread resurrection, firstly because the way that cars are getting snapped up at higher prices at the moment suggests there might be a few newish owners around these parts, who may enjoy a bit of reading about attributes of their new cars that aren't value or spec related. And secondly, because I have a new little factoid to add.

Front-end rattles - in years gone by there have often been threads about front-end rattles that owners (and garages) have struggled to diagnose. From memory the comments I saw were usually attributing the noise to any of ARB droplinks, top mounts or the dampers. Owners would say it was mostly the noise that was irritating and there was usually no ill handling effects.

A new source (to me at least) suggested to me by NineExcellence is the front brake pads.

Something like this - it is not uncommon that they can rattle around in the calipers even with the correct shims etc because the adhesive soon breaks down with very high brake temps. A way to test is have one's foot on the brakes very slightly when going over a rough surface to see if the rattle disappears. I spent a long time being paranoid that my car had some worn bushes/links/dampers, but they all check out OK and I still had the rattle after a while. Now I can get on and enjoy my car and not care about that occasional rattle.

[braddo]

Yep.

Think of if it as a heads-up that if an owner notices a new rattle at the end of a day of track fun or alpine passes, for example, it's worth checking if the brake pads are the source before assuming that a suspension component has worn out during the day.