997gt3north

Most of the really fast drivers of 2007-2008 gt3 and RS that I know of found that, in the dry, these cars with the OE rear sway bar, even on firm as delivered by the factory, would push too much / the rear was too planted. You have further softened the rear bar and added a larger rear tire so you will likely find in tighter corners that you can't get the car to rotate how you want as the grip in the rear is just overwhelming the front.

Now, with the above said, as you are learning the car and you are at a fast place like SPA, having the rear out grip the front may be a good thing.

As your comfort grows with the car, my guess is that you are going to have to get the rear bar back to stiff, or change out the rear bar for the stiffer GT2 bar as many have done - including me - on Hoosiers I like the gt2 bar in the middle position on PSS I like it on soft - I run the front bar one stiffer than the factory setting in the middle.

I have spent a lot of time setting up my 2007 gt3 and like the following setup

-2.3 front with zero toe running a 245 tire with rotated struts and a 7mm spacer with the cup front splitter
-1.75 rear with 2mm toe in, gt2 bar on soft, RS wing at 12 degrees, Guard LSD, all the RSS solid stuff in the rear
- car is lower 15mm in the rear and 10mm in the front
- I'm running 600/900 springs on re-valved OE shocks

The above car is predictable, neutral and can be driven by a student and a pro - both will like it. The car has a hint of rotation on 2nd gear corners and is dead neutral in 4th gear corners - I believe my RS wing at 12 degrees, cup splitter and 50/80 Guard LSD contribute significantly to my setup.

FFaust

Do you know, or could you measure when you get a chance, what the distance is from the center of your wheels to to bottom of the fenders? (front and rear)

997gt3north

Francois,
- as best i can measure, both front and rear are exactly 13 inches
- how does that compare with what it is suppose to be for a 997

thanks

pvdw

NOW THAT'S A TRACK TOY !

Will do.

See you in just a bit for another greatest weekend of the year!

Best regards

pvdw

My first idea was 245 front to add front grip and reduce some of the push...
Switched tyre size to 325 in the back in order to maintain ratio as close to stock as possible...and figured the additional tyre width would create indeed a more planted all round .
Will find myself with more push...

What about going to middle sway rear and one of middle towards stiff in the front to stiffen it up just a little ? Would this create a more neutral handling ?
Think the stiffer setup might just be needed in order to event rub

Had the wheel supplier on the phone today, confirmed they had fitted non RS with ET51 before and it depended on suspension setup whether it would fit or not, has asked me to try it out and if no go, would replace with different ET's (back order for couple of weeks)
Will try, post pics and keep updated.

FFaust

Thanks Paul, I think that 13" is the magic number all around. At least that is what Gianni tells me, and I think that it goes for cups too.

I replaced my shocks this winter and have not yet done the corner balance. I tried to set up the car with approximate heights I read here and there, and ended up with 12.5" in front and 13" in the rear. I have 105mm front and 120mm rear at the "official" measuring points, so 15mm of rake.

Car is much improved from last year (also did a Crawford wing), and I'm not sure how much better it could be with proper corner weights...

997gt3north

your front and rear measuring points are different than mind for sure as I have different tires

i did my best one day to get under the car and do the real measuring points and I'm pretty sure I was around 95 in the front and around 110 in the rear so around 15 like you said but i'm lower which sort of doesn't make sense since I'm probably running taller tires but I'm pretty sure i was 'close' to actual

for sure, the rear has been dropped my more than the front


thats a big wing - i'm assuming you are running that new 996 front splitter that guys are now buying and 2 canards per side

FFaust

I'm trying to figure out ride height, but I think that I am high. Olsen Motorsports, who sold me the shocks, says that 95mm and 110mm is the way to go. The fender measurement is just a quick reference.

I have 2 of those new splitters, but have not had time to install them; still running the cup one. I also have a Crawford splitter, not installed either. It's a flat board that goes under the normal cup splitter and extends forward about 2". Only still have the small canards as in the picture below.

I am still experimenting, but so far, there doesn't seem to be a disproportionate amount of push. That's doing 35's at Mosport however, so not on the edge.

To be continued...

FFaust

pvdw

Shouldn't have doubted Rennlist wisdom...
Doesn't fit ... Not even close... 1,5 cm too much outwards

Ordered the correct ET68 wheels, just probably won't have them in time for spa, bummer, looks like I'll be running on the standard wheels, using up a otherwise perfect set of street mpss, while the trofeo's lie around waiting for rims, argh!
but then again, ran for three years on the 993 before switching to semis slicks so I guess it will have to do.

utkinpol

rake setup is an interesting topic. I used to have it flat 13/13 and then lowered front a bit so it changed into an inch of a split so front now is at 12.5 and rear is at 13.5 and I think it works better for me this way with having a bit more more weight in front.

to OP - try to set sways at middle holes both and get used to that feel first. You are on stock springs and with soft springs you need a bit more sway bars to reduce roll, with stiffer springs like mine or North`s it is not so critical and sway bars are more of a fine tuning thing compared to stock springs. I run now front on 3rd (counting from softest) hole and rear on middle. It improves mid-corner stability while adding a bit of initial understeer but car at mid-corner slides pretty equally on both axles and it is exactly what I want so I can control it nicely with throttle without causing complete loss of traction.
a lot of people set front sway to full soft initially as they 'feel' that car does not grip in front approaching the corner but it will result in loss of traction mid corner as your speeds increase. goal is to have both axels to slide out predictably when u get close to 9/10th so it will take time to tune it up.

PS. anybody got a picture of an 'official' spots to measure rake? as it seems that a lot of ppl use different spots to get that measurement.

FFaust

Not sure if it's the same spot for regular car though.

utkinpol

thanks for that. it is quite difficult to reach in front, I tried but it is not very accurate, something from 105 to 110. anyway my rake is dictated by my garage`s driveway, I now just scrab it a bit with my front spoiler so it cannot go any lower anyway.

Protocav

Are you guys feeling like the car has more front bite with the nose down a little bit?

Mine pushes into turns, and on throttle out. The only time it doesn't push is mid-corner, completely off throttle.

To be fair, I have no idea what the ride heights are, but I plan on taking care of that.

utkinpol

i would advice to get a good experienced guy/instructor/coach who owns 996 or 997 series car and let him drive your car. it is impossible to 'guess' it just from a forum input if car is tuned properly or not.
a lot of how car behaves in a turn depends if you manage weight transfer correctly and indeed if you will try to 'coast' in mid turn any 997 car will push. it has to be a nice smooth transition with trail braking to preload front, then you transition into turn loading one side and then adjusting throttle (depending of a corner radius changes) to keep that side loaded enough to remain at grip. kinda easy to say but takes some time to get that on a reflexes level to 'feel' when car is biting well and when it can unhook and start slipping out.
honestly it is why i do not like tracking in a street car with no cage much anymore as it is kinda easy to loose it suddenly when you drive it like that and then, well, it may hurt. especially if you do not get to track every other week and your reflexes become more rusty than it should be.

anyway, with me when i bought this car and started learning how to drive it after Miata and bmw it took 2 seasons doing AX runs almost every weekend and spinning it a lot at AX to figure out how to deal with weight transfers and entering turns 'correctly'. i think it is just a learning curve that has to be done one way or another, only to do it on a track is much more difficult as speeds are higher and cost of a mistake is also way higher if you meet the wall there. compared to nice free spin out on the empty airfield strip. but i am absolutely positive - only way to learn how to prevent a spin out and learn how car behaves at the limit of losing grip and how to play with throttle to 'catch' it back, etc, is to do a lot of those silly spinouts. and during this process you will learn pretty much everything about how your suspension works and can be tuned.