997 GT3 Geo Settings - time to learn

[Steviebeee]

Hi guys,

I've had my car set up many times, some good, some not so good.

I've started using a new guy and for the first time I've had a print out showing all settings. The cars driving great, nice and stable with lots of rear grip in corners and steering that's not pulling me all over th place.

Here's a brief run down on the current settings (from memory!)

Front Camber -1.5/-1.4
Front toe 0.15

Rear camber -1.6/-1.6
Rear toe 0.20

The ride height had been adjusted previously and sits lower than standard, lower at the front than the rear, which I believe is to help with steering feel.

I'm only just learning this and it's great to actually see my settings to then go forward and adjust to my driving style. As I said, never got this before.

The car is predominantly a road car with only two track outings per year.

Look forward to hearing what others run and feed back on the above.

Cheers,
Stevie

Edited by Steviebeee on Thursday 26th September 21:39

[mrdemon]

more camber less toe, ie no front toe at all.

[Steviebeee]

Thanks MrD,

More camber front or rear? By how much?

Stevie

[mrdemon]

it's a tough call.

the reason I sold my car was it was too much on the road but it was a 996.
The ARB caused me the biggest issues being too stiff even on soft, so the car was just a pain to drive at speed on the road.

I run zero toe on my Cayman R and would like about -1.8 on the front with about the same on the rear for hard core road use..
the rear just a tad of toe in to keep the car straight.

Not sure about the 911 settings.

but def no front toe I would say and def more neg front camber.

The track GT3 boys runs loads , so you need to decide what you want from a GT3 I guess, being more a track car than a nice road car.

Also the rear ARB's were changed at some point on 997 GT3's due to them being a bit under steery. (so a stiffer one was fitted)
you might have to check what you have.
The front ARB will cause you bump steer issue if to stiff. and that's where you have to choose between road manners or track toy also.

Some will say you can run -2.5 on the road no issue, but I had perfect shocks and a damper rebuild and my GT3 rear tyre inners were shot with that much camber on them.

SO I guess some one else will give you a better set up, just don't go to mad with it and have too much camber you will never use.

Edited by mrdemon on Thursday 26th September 23:12

[d41d8cd9]

mrdemon said:

The front ARB will cause you bump steer issue if to stiff. and that's where you have to choose between road manners or track toy also.

I don't think you know what bump steer is.

[arcamalpha]

Steviebeee said:

Hi guys,

I've had my car set up many times, some good, some not so good.

I've started using a new guy and for the first time I've had a print out showing all settings. The cars driving great, nice and stable with lots of rear grip in corners and steering that's not pulling me all over th place.

Here's a brief run down on the current settings (from memory!)

Front Camber -1.5/-1.4
Front toe 0.15

Rear camber -1.6/-1.6
Rear toe 0.20

The ride height had been adjusted previously and sits lower than standard, lower at the front than the rear, which I believe is to help with steering feel.

I'm only just learning this and it's great to actually see my settings to then go forward and adjust to my driving style. As I said, never got this before.

The car is predominantly a road car with only two track outings per year.

Look forward to hearing what others run and feed back on the above.

Cheers,
Stevie

Edited by Steviebeee on Thursday 26th September 21:39

My car runs -2deg front and rear with zero toe front and a little toe in at the rear. Arbs are all in the medium position. Ride height is slightly lower at the front to make the front 25mm lower than the rear. Works great on the road and pretty good on track too.

[Trev450]

You may find this thread useful:

http://www.pistonheads.com/gassing/topic.asp?h=0&a...

[mrdemon]

d41d8cd9 said:

I don't think you know what bump steer is.

thanks, I knew this would come up :-)

yes it's all about pivot points, and centre lines of your steering and the like etc etc.

But when done and said all, if you have the ARB on stiff the car will move without steering input causing Straight line instability.
SO sort of matches the def of bump steer in a way :-p
"Bump Steer is when your wheels steer themselves without input "

So it feels the same :-), hit a bump with one wheel and your car will move without steering input.

And while not the tech term for bump steer, it feels the same imo and does not have a name I know off.

If what I am describing has a name, let us all know please :-) thanks.

[fioran0]

Oh FFS
bumpsteerfail

Stevie, you just learned the most important lesson you will ever learn in your GT3 ownership. You are always on a bridge even when it doesn't seem like it.
Trip trap trip trap

Edited by fioran0 on Friday 27th September 11:43

[keep it lit]

d41d8cd9 said:

mrdemon said:

The front ARB will cause you bump steer issue if to stiff. and that's where you have to choose between road manners or track toy also.

I don't think you know what bump steer is.

you can add that to a long list.

[ttdan]

OP that looks like factory settings for a 997 which, in IMHO is just fine for road use. You can add a load more camber and wear your tyres out if you want to.

[Steviebeee]

Thanks MrD,

I think the handling characteristic of the two cars maybe a bit different, but suspension changes must still, fundamentally, have the same effect on handling.

Bump steer, I always thought, was the positioning of the steering arms? Not ARB? Still, I'm a novis at this so I'll leave that one bee for now

Arcamelfa,

I might well try adding more camber, but def going to try the zero toe at the front. Arbs are stiffest rear and second stiffest front, don't think I'd want to soften the rear any as I like the bite it gives the front.

Hi fioran,

You got me here! Bridge? Please enlighten me! Your posts always have much meaning, although this ones a little hidden

TTdan,

I think you are right as the settings came off my friends machine which lists settings for just about ever car on the road. It feels good, but everything feels good until you try something better My friend has just invested a lot of money in his geo setup, so playing around with the set up has never been more accessible. I would like to take advantage

Thanks for all the posts guys, keep them coming.

Stevie

[sportsandclassic]

Hi,

Have you checked the ride heights and corner weights?

Once those are checked and correct. Then try -2.5 front camber 1-2 mins toe in per wheel.
-2.2 rear camber and 12mins toe in per wheel. This will give a fantastic setup for your car.

Keep the rear sway bar on full stiff for now and back that front bar off to centre hole.

Let us know how you get on.

Mike

[Steviebeee]

Thank Mike, your a gent. I appreciate tyre wear will be a bit more, but the car doesn't do serious mileage anyway.

How will I be on the motorway with these settings? Some of my fav roads are 50m away via duel carriage ways.

Stevie

[Steviebeee]

Mike, quick one - my rear toe keeps moving making the car really unstable. My last geo guys said he put new bolts in last time (4 months ago), as I learned they are susceptible to stretching and not holding the settings, but I got the geo done again last week by a new guy and after one adjustment and one week running the car it's out again at the back. The toe was out before the latest geo was done. Are the toe bolts really that poor?

Thanks,
Stevie

[fioran0]

They are useless. Toe locking plates and adjustable arms should be the first thing on the list when anyone buys one of these. Its cheaper than needing alignments every time you go near a bump and rear toe is the most critical aspect relating to alignment on these cars.

[Steviebeee]

Thanks Fioran,

RSS items do the job okay? I'll just have to switch back to the std items come warranty renewal. That's what's been holding me back from getting them, but the constant geo to keep the car 100% is becoming a pain. I thought new bolts would have done in the mean time? Obviously not.

Shopping! Any recommended websites?

[keep it lit]

fioran0 said:

They are useless. Toe locking plates and adjustable arms should be the first thing on the list when anyone buys one of these. Its cheaper than needing alignments every time you go near a bump and rear toe is the most critical aspect relating to alignment on these cars.

^

[sportsandclassic]

For road and track use you will be fine with std camber and toe adjustment bolts.

I run std bolts and have not had any movement on any of mine, I mark mine with paint to check and after a 1500 mile round trip to Spa and 400 miles round Spa they have not moved. Was on Michelin Cup tyres so quite grippy.

Have had the same bolts in for over two years now and never had a movement issue, I do know of cars that have moved and they have been down to lubrication products being applied to the back of the eccentric cam on bolt head, it needs to be dry so,it can grip and tighten up.

I run the 997 cup rear toe arms on mine as when I installed them you could not get hold of RSS ones. Fitted loads of RSS parts and the quality is great.

Are you sure the settings are moving ? Did you paint the adjusters and confirm this, or is your steering wheel moving off centre?

Even 996 cup cars did not run lock out kits, I have been off onto the green stuff recently at Oulton park and went over some serious rough terrain! my geometry has not altered as checked it all on wheel alignment machine. It will take a fair old wack to make a suspension arm move if anchored down correctly. I have seen road wheels ripped off the carriers and the adjusters still look intact and secure.

Mike

Edited by sportsandclassic on Monday 30th September 07:07

[Steviebeee]

Hi Mike,

Yes defiantly moved. The cams were all painted. It's also the side I thought that had moved..it's only a few deg, but I'd imagine that would be enough to put the toe angle out. Also, I'd imagine its moving more under load too?

Stevie