nkhalidi

I never implied that adjusting tire pressure was in any way related to tuning the suspension; I wrote that adjusting tire pressure is a way to dial in/out understeer/oversteer.

That said, I'd argue that understeer and oversteer are both loss-of-grip situations, and that making one end of the car lose grip before the other (by adjusting tire pressure) is a valid way to quell a car's tendency to oversteer or understeer. Not ideal, but valid.

In an ideal world, Ron would get a high-zoot suspension setup, dial his alignment to fit every track, and have the car corner-balanced to the nth degree. But iirc, Ron doesn't even want lowering springs (a relatively inexpensive way to eke out more camber all round) because it'd reduce his car's clearance.

10 GT3

While there is understeer present, it is no where near as bad as an E46 M3 (especially with the optional 19" wheelswith wider rear tires). I find it very strange this method of tuning cars to be any safer by limiting front grip. You could just as easily be killing hitting a guardrail plowing through a corner at a high rate of speed as you could having the back end swing out. Both cases are driver dependent. With the 911 they having always been working to tame the back end. The E36 M3 on the other hand had a perfectly neutral balance and they destroyed it with the next version.

The primary issue with the understeer is not an issue from camber, but of balance from weight transfer. If you want to reduce understeer, you need to change the weight transfer. Wider tires will change the shape of the contact patch, not increase it or change weight transfer. Understeer is tuned into cars for the US as our suspension here are very different than what the Rest Of the World (ROW) gets. The regular suspension on the US 996, 997 and the PASM suspension on the 997 they are set up to confortably understeer at the limit. The optional US M030 Sport suspension, ROW M030 Sport Suspension and X73 Sport Suspenion all are very neutral out of the box with similar alignment settings. The primary differences are the rear springs are substantually stiffer (at least 25% stiffer) than the standard suspension while the front springs are only about 7% stiffer. The rear roll bar has about twice the increase in diameter as the front roll bar over the standard suspenion to help shift the balance further (all 3 factory performance suspensions use the same roll bars).

So what to do to change the balance? Swapping to a ROW M030 would be a tremendous handling improvement, but you lose your electronic shocks. If you want to keep them, I would recommend to start with a good set of adjustable anti-roll bars like TRGs.

I noticed a lot mention high levels of camber. You aren't going to get over -1 degree in front with the stock suspension. In order to get -1.5+ you will need camber plates or adjustable control arms. The inexpensive camber plates are designed to work on smaller diameter coil-over suspension like the GT2, GT3, X73 and PSS9's. There are some that will work with stock-type suspensions, but they are around $500 and you can't move them that far in or the spring hats rub the shock towers.

The other option is GT3 control arms (there is a lot of information on this in the mod forum from my GT3 control arm swap). Again there is a compromise as the larger the shim pack to increase the camber, the greater the tire rubbing/clearancing issues and the track arms can bind up. I am currently running -1.6 in front with a ROW M030 suspension and GT3 control arms with a 7 mm shim pack. We are going to increase it to -1.8 to -2.0, but that is all we will be able to get before it really screws the front geometry up. If you go to a coilover suspenion with GT3 style camber plates, you will gain -1.0 camber extra just from the camber plates.

RonCT

To answer some questions to allow you to provide more information on style for a 997S...

I've been in the most advanced-solo run groups for 2+ years. In the M3 at Lime Rock or Watkins Glen I hadn't been passed for a long time - maybe a year. Not sure of lap times - didn't have a device. My 1st day on the track with the 997s was in late March - no timing device yet, but relative to the rest of the Black (advanced solo) group, I was passing a lot and was only passed a few times. On my 2nd day on track with the 997S at Lime Rock I was running 1:04s-1:05s per TraqMate and on my 3rd day (this past Thursday) I was running 1:03s and 1:04s. I figure that's not too bad with a bone stock 997s on street tires. That gives a general snap shot of where I am on the driving ability curve.

I know I have a lot to learn about how a 997 likes to get around the track - I've only been in it 3 days vs. 4 years and dozens of track days in the M3. I'm already getting some of the nuances of the rear-engined car via my 3 days in the seat and some of your comments. For example, the weight transfer / trail braking concept. At LRP, the places where I had more understeer than I wanted was as I was coming out of a turn (obviously) and as I was on throttle from apex to track out, the car was just pushing more than I was used to or expected (coming out of Big Bend in particular was the worst). I could ease off the throttle to put more weight on the fronts to steer, but then that theoretically felt like it would be slower overall. So I'd just muscle it through using the big rear wheels. I've been hoping to get a rear-engined instructor guru to come out with me for a session, but none have been available. Perhaps at Cups & Saucers I'll get lucky.

It sounds like the best bet for me would be:

1) Get the R-comps, which are now very late in getting to me. I've decided on RA1s in 245/305. Wheels will be 18x8.5 and 18x11 Fikse Profil 13s.

2) Have an expert shop like FBL tweak the alignment as much as is practical with the stock setup. Upwards of 0.80 is the maximum. Maybe in the future, go with GT3 Cup control arms for more (I just want to keep suspension stock as much as possible).

3) Seat time and help from others like you guys - tips on driving style with a 911 vs. M3.

kauai_diver

That's pretty impressive for street tires!

Last time I was at Thunderhill there was a guy with the Michellin Sport Cups (r-comp) on his 997S and I couldn't keep up with him in the turns. They make a huge difference.

PAULSPEED

Hi,
You need new camber plates and H & R racing springs
to improve your lap times.
Paul

jrgordonsenior

I think the question becomes how far do you wish to modify this car for better handling performance?
There are many good suggestions listed previously such as after-market coil overs and GT3 control arms. Bilstein, who makes the factory PASM shocks, finally has stock again of their PSS9 for PASM system which is controlled electronically same as stock. H & R also makes an even beefier coil-over system but not for PASM if that's important to you. I've raced against and driven a 7S with H&R's and it's quite a difference. Either of these systems will allow your greater flexibility in your setup options. A larger rear bar, whether ROW or aftermarket would certaily help too though I'd leave the front bar alone as it's thick enough as is.

Your choice are probably defined by budget. I would start with coil overs and a rear bar. If you choose to modify the suspension, stay with your street tires for the first few sessions to get the experience of how differently the suspension feels and works. Once you're comfortable with the new setup, then throw on a set of R compounds and go to the next level.....

Oh and some better pads will become obviously necessary shortly thereafter...

stiles_s

This is a random question for this thread, but this is the largest concentration of non gt3 997-trackers I've seen.
Are any of you guys seeing evidence of oil starvation running the R-compound tires? My old '03 996 would visibly and dramatically lose oil pressure on hard right-handers (on street tires)...

Thanks (kicking around the idea of a 997s)

jrgordonsenior

The 7S has a series of fins in the block which are intended to keep oil from being pulled away via gravitional forces during heavy cornering. I've never heard anyone comment on their usefulness....

nkhalidi

No. The car did burn a couple quarts in the first 3k miles, though. Seems to have levelled off after my first oil change, all is well.

Bullet

The best advice here is to be mindful of weight transfers. My advice is to squeeze the throttle on those turns, like you would the trigger of a gun. By simpl changing the way you transfer weight and throttle (smoothly), you an turn that into oversteer.

-B

Deanski

Ron,

I'll be Chip over at FBL will be able to dial in the right amount for you.

I'd also see if you can get Spencer to go with you on a track event to let him feel the car as you drive prior to putting it on the rack.

In the future, I'll bet the new Bilstein PSS9's for PASM would be your best option. This way, you can not only lower it, but also keep the PASM ability AND have the ability to adjust them when you get to the track. When your ready to leave, another adjustment will put you back for street use.

I'm dying to have these installed. It's been very busy for me and since I've even yet to get to the track... Well, soon I hope.

FBL has had very good results with the Yokohama tires. Or you can go with the cup tires which are like flypaper.

I'd reach out to the FBL team and let them "steer" you in the right direction before you start adding tires or other options.

Hope to see you at the track one day!!!!

Regards,
Deanski

RonCT

Thanks Deanski - I'm waiting to hear back from FBL (talked to them Friday and emailed with a detailed list of wants). I've had great success with PSCups, but am leaning to RA1s for this car because I can't haul a 2nd set for rains (really don't like cups in the wet - RA1s will serve me better). Spencer did mention the PASM PSS9 to me the other day - will research that further.

See you at the track!

jrgordonsenior

FWIW, Rennlist sponsor AWE has the PSS9's for PASM at $2,500. I've heard tell FBL's was pricing them much higher earlier this year......

http://www.awe-tuning.com/pages/shar...ilsteinPSS9997

Dan_997

Added the PSS9s to my '06 997C2S last week and had it lowered about 1". The alignment is what you might call an aggressive street alignment and I don't have the sheet with me to provide the exact specs. What I noticed on the track yesterday was the car is much more neutral with less understeer. Perhaps with a more aggressive track alignment and thicker anti-sway bars understeer could be dialed out completely.

Of course were talking about a car that is driven about 6 times a year on the track and 359 days on the street. So, I'm not trying to make this a serious track car but just wanting to have some safe fun at DE days.

IMO to make this car more competitive as a track car would mean losing about 1,000lbs and basically destroying the streetability.

PAULSPEED

Hi,
There are fins in the 997 S to keep the oil from sliding around. The
GT-3 has more and bigger fins.
Paul