For tire sizes, here is what we are running now:
Front - 18x10.5 with 285/30 or 295/30 - 3.5 degrees camber
Rear - 18x13 with 335/30 - 3.1 degrees camber

VID997, for the front axles life, we use a combination of camber plate (pulling in) and lower control arm changes (pushing out) to keep the axle plunge depth close to stock. That seems to be working so far, only one track day of extending running, but a few hundred street miles too.

For the rear axle, I was dropping the clutch pretty hard, and the concrete was grippy. Datalogs showed some spikes to 1.2G at the clutch drop, usually that is only about 1G. We had reduced rear camber from 3.5 to 3.1, so that probably also gave more bite.

 

Lots of activity in the weeks between the Florida event and this one. We ran a couple of test events, testing different front spring rates, and tire sizes, trying to improve the package.

The Cobb Plano team has now transitioned Growler Motor Labs, (as in growling engines). The team continues as strong as ever, under the new ownership now of Chris Fleming, Cobb Plano's former general manager. So time for fresh branding! New graphics are the fun part of the job.




Warthog was starting to show some wear in the knees
We decided to replace the passenger side axle preemptively with a new OEM unit. While on the lift, the Growler techs found a worn driver side rear wheel bearing, and a worn front control arm bushing. Wheel bearing was easy to pick up from our local dealer (Porsche Plano) but the control arm bushing was a specialized Powerflex eccentric unit.

A big thumbs up to Powerflex usa, Vorshlag, and Growler for coming together replacing the worn bushing under the lifetime warranty, and getting a new set overnighted to us. Now we could finish the corner weighting and alignment.

Testing guided us back to the original spring rates (750/1000) but a change back to the 295/30/18 front A7 tire. The 285/30/18 fit more easily in the front wheel well, but was a more prone to front lockup/abs and understeer.

With the maintenance done and the wider front tires, the handling was terrific on the old airfield concrete. I had to dial in a bit more front swaybar as the new front grip was kicking the tail out a bit too much, but it was perfect after that. My competition this weekend was the corvette team which has won the class championship at least 3 years running. Iw as able to stay on pace with them all day saturday, and was able to jump ahead on my last run on Sunday My wife was able to place 4th in her combined class, and also make it into the challenge rounds on Sunday.

The challenge rounds on Sunday were great fun, I made it to the 3rd round, before knocking myself out with a redlight.

Overall a great weekend, with the handling nailed down, I can focus on maximizing the driving technique and courage to use all the grip the car has.

 

congrats man...crazy how well that thing dances!

 

So inspiring, that car remains flat as hell through the cones.

 

Thanks for sharing, it's a cool journey!

 

Wow Stan!

Great thread!
I'm so inspired by your build and on task at constantly raising the bar!
Truly a car and driver in harmony!
Talk about owning the experience!!...

 

From our last Pro Solo event at Mineral Wells. My lovely co-driver had all wet weather runs on Saturday, great place to show off the grip and control of the 997TT. We mounted our hoosier wets that were at least a couple of years old, on some heavy aftermarket cayenne wheels. First time to use these ever, so we learned tire pressure and shock settings along the way.


She had over a 3 sec lead after saturday, and backed it up with dry run wins on sunday.

I got to co-drive the other Growler Motor labs race car - a fully built STI in low power trim at 500 ft/lbs. It was a handful in the wet with it's hoosier slicks.

All done with major events now until the Solo Nationals in September, I have 2 class wins, and Su has a win and a 2nd, so we have fulfilled our points requirements to be in contention for the year end class win. Time for some refurbishment, new front rotors to replace some cracking oem ones, fixing broken front shock adjuster, and just general tlc.




If you notice, the garage seems a bit different, in the middle of the season, we sold our home in the burbs and moved out to the country - pilot point, north of DFW.


Almost 8 acres, but need to build a shop and some stables this year. New tractor is for brush hogging and loader work. Lots of chaos, but glad to be moved in late May. Thanks to the Growler Motor Labs/Cobb Plano crew for having Warthog as an extended house guest for a few weeks while we were moving.


It is not too uncivilized. Have a decent local brewery nearby in Denton for after mowing!

 

Oh man, clearly what you need to do now is pave a practice track - I mean, totally legal meandering driveway - around your property!

 

beautiful thread,

running those tyre sizes, did you face any issues with the transfer case?

295 30 18 with 335 30 18 any issues?
285 30 18 with 335 30 18 any issues?

 

Is there a definitive parts list for making the car handle its best? Like for power, most follow a similar roadplan (exhaust, clutch, tune, intercoolers, injectors)

For a mostly street setup, with occasional autocross, what would that specific list be without going into the extremes like Moton.

 

So far no center diff/clutch issues. We have been checking the fluid, and changing it every 9mo. or so. Planning on doing some data logging to see how much it is actually engaging in the different modes.

For Roffle, this is the order I would go with for handling enhancement:

Basics - must do's
- Performance alignment - max front negative camber (only about 1.5-2 deg) and about .5 deg less in the rear. Toe front - zero, rear - 1/8 to 1/4 in in.
- Fresh performance tires - pilot sport 4's, Conti extreme contact 4's, bridgestone RE71r. This new generation of extreme performance street tires are so good, they can transform your drive.
- GT2 rear sway bar - it is much larger than the turbo bar, and 3 pos. adjustable. It will helps tune out some of the understeer, and you can build the other mods on top of it.

Damping - multiple choice here
- DSC sport controller - to help stabilize the platform better. This is a good place to stop and enjoy the improvements, as the sportiness and comfort of the car is still very good.

Damping and Lowering - Now the ride gets firmer, more controlled, and you can corner weight and lower to match your tracks and back roads. You can enjoy these setups on track, autox without having to do anything further.
- Bilstein PSS10 - will still work with the DSC Sport controller
- Ohlins road and track - manual adjustments

Off the deep end... if you decide to go extreme...
Increase range of adjustment - when you want to maximize tire traction, and remove bushing flex.
- rear adjustable toe links
- Front camber plates
- Rear spherical top mounts
- gt3 style adjustable control arms
- spherical inner arm bearings

Increase grip - time for more rubber!
- wider front wheels and tires - 9-10", 245-265 width
- wider rear wheels - 11.5-12.5" and 315-325 tires
- 18" wheels? This was more usable 2-3 years ago, as tire choice was good, and cheaper. Now more of the top street tires are only made in large 19" sizes. (michelin comes to mind). I would go 19"
- LSD upgrade - The turbo 22/28 locking LSD is not too effective. Updating to 997 gt3 ramps (27/40) or 996 gt3 (40/60) or cutom Guard unit. Freshen the clutches with guard replacements.

 

yes this would be great, will definitely answer alot of questions on what the transfer case can handle healthily on the 997 turbo 4s platform.

 

and regarding roffles comment, im in the same position as ive just started tracking the 997 turbo

just changed pasm stock absorbers with eibach springs
front max camber -2 toe 0
rear -1.5 degree camber total toe in 0.12

rear GT2 antirollbar 3 holes, middle hole, so medium

i have considered the dsc sport controller but is it beneficial on the track? as when i have the PASM full hard its proper firm and i dont find the suspensions bottoming out however i do still have alot of understeer.

i have considered camberplates as it allows adjustment easily but i saw on your thread that it would hinder the front drive shafts. there for im considering the powerflex front camber bush pff57-801.

what is your take?

 

Thank you so much! How much negative camber in the rear can I add without compromising straightline grip?

I currently have lowering springs part number GMG997TTWCR (219146). Doesn't seem like they're coilovers because I don't see height adjusters on them.

Car has 30k miles. OEM LSD option.

For tires I'm running stock size Bridgestone RE-71R.

My impression on a small autox track, is that there's room to improve in body roll and also there's a noticeable delay between steering input and body motion.

I don't want to run super aggressive negative camber since I mostly drive it on the street

 

Your settings look good, the easy first step is to change the rear sway bar to the stiffest setting. That will help in all 3 phases of the orner. Some of the understeer bias may be the spring rates, which are not easy to change without switching to coil-overs.

PASM in the sport setting sets the shocks to full stiff, which does not help understeer on turn in. DSC may help with keeping the front soft initially, but it's price is high.

With camber plates, you have to check front driveshafts still have some free play. Up to about 3 degrees you should be ok. But they will add harshness with the solid bearings, so consider that.

Another option, may be a wider set of front wheels, maybe just for track usage, with an increase in tire size to 245 or 255. That may be more cost effective than extensive suspension work!