scss98

Thanks. Maybe a problem with track surface at Lime Rock.

insite

my bad; must have been dyslexic that day

wouldn't worry about it in that car. very little play i think; i doubt if you'd toe out under braking. too much toe in back will just make it really hard to rotate.

insite

out of curiosity, what causes this phenomenon? i'm totally unfamiliar with PASM and its nuances; i've never driven a car that was so equipped.

Bob Rouleau

Update - Three days of tracking the RS and I am happy to report that the car now handles well, sharp turn in and no understeer except in slow corners - which is typical of all 911s. With the settings below the car ran with the big dogs (finally!). It was especially impressive for stability in the infamous McLaren (turns 1-2-3). The car was planted - perhaps the big *** wing did it but the car was confidence inspiring in what is normally a butt clenching complex.

Front Rear
Toe 0 16 mins per wheel
Camber neg 2.5 neg 2.0
Caster 8 deg
Sways Full soft Full stiff
Wing Max angle
Height Factory spec.

At Le Circuit the car was a pleasure to drive and quick. I will probably fiddle some more but this set-up works quite well. Ran Michelin Cups 19 inch N 0 spec 32 lbs F 34lbs rear hot pressure.

Now for 18 inch rims so I can use the stickier Cups which are not the N0 Spec.

Best,

mitch236

I'm very happy that you got your car better sorted. BTW, you can get the 19's in a normal MPSC. Not that I really recommend them, but it is available. 18's give you so many more options except that there is a national shortage of MPSC's in 18's for our cars.

CWay27

Funny but yet so true.

Glad you got it sorted out. Were Ron and/or Apex also there to witness the changes??

Apex Late

Hey Mitch,

Where are these "normal MPSC" tires available in 19? I wish I knew about these earlier.

Erik

I wanted to run Sebring before I commented on this issue, since Moroso is kind of a weird and VERY slippery track. Last weekend, I was having the understeer issue myself, only in Bishop Bend, which is where I was hoping to be able to dial it out. I went so far as to put my front sway all the way to soft, leaving the rear on full hard. This is a turn at about 120 mph, and on the first day I was running with full wing, which really made the car feel great under breaking and other high speed turns at Sebring such as turn 17 and turn 1, but slowed me down by about 7 miles on the straight away. On Sunday I put the wing back to stock, to see if it was not pushing the rear end down too much and therefore lifting the front, but it did not make any difference in push. My car is alligned per the track settings in the manuel. I tried both the sport and regular shock settings, but on sport I was about 2 seconds a lap slower. I was doing 2:27's with my best settings, which is not bad, but something that I could also do in my 996 GT3. Next time I will have 18" rims, and we will continue the experiment.

Apex Late

I was there and Bob was running very well.

However, I struggled with my set up for most of the weekend. The car worked extremely well on Monday afternoon when I was running 32 lbs front and rear. By Tuesday the same pressures didn't work well with the different track condiditons that were present on Tuesday and the car began to understeer in the fast corners. I chased the understeer with pressure changes but never managed to find the sweet spot again. On Wednesday I started over and the car started to push in both the slow and fast corners putting me closer to the edge than I wanted to be. After 3 days of driving I never achieved the performance that I had in the 996 BUT with the sessions that I had that were good it was clear to me that if we get these cars sorted the 996's will not keep up. The apex to exit excelleration is just too great in comparsion.

After taking a hard look at the front tires I'm convinced that a good bit of the understeer comes from the channels that are present in the N spec tire. There is a little more than an inch of missing rubber with those damn things there. After 5 track days mine are done and I've gone past the wear bars (which may account for my problems on Wednesday)

Like Bob I'm going to play with the set up a bit more BUT I'm not going to touch it until my 18's arrive as I don't think that the 19's with the stock MPSC's are really ready for high track speeds. Mitch has said that we can get the real cups in 19 so I will wait for some news on that front. My GMG wheels should be here next week so I hope I won't have to wait too long.

Summary: Still somewhat disappointed but still hopeful.

Apex Late

This is very interesting as my best laps by far were in the regular setting and everything just seemed worse in the sport mode.

doc2s

regular cups come in 19s for the front size but nothing for the rear that i could find.

Edwin

[QUOTE=Apex Late]After taking a hard look at the front tires I'm convinced that a good bit of the understeer comes from the channels that are present in the N spec tire. There is a little more than an inch of missing rubber with those damn things there. /QUOTE]

My car came with Corsas. I didn't have notable understeer issues at TWS except at the slow carousel turn. Perhaps the tires are playing a role in the understeer (I haven't changed anything from delivery as of yet).

I may not be driving as close to the limits as you guys though. The 997 GT3 is so superior to my 996TT that I am turning 5 seconds quicker lap times without any feeling of peril and probably not pushing the car at all.

Bob Rouleau

997GT3 - several of us had Corsa's as OEM and found that the cup tires have better grip than the Pirellis when pushed hard.

Mitch I am also curious about 19 inch Cups that are not the wide groove N spec. I was told they were no longer available.....

Best,

grussell

They are BMW spec and they are only available for the front.

mitch236

You are absolutely correct! I was relying on a friend for that info, I guess I should have checked. Anyway, I am running 18's so I just trusted him about the 19's.

Erik, I would wait until you switch to 18's to start making alignment changes. You should have less understeer with better tires. BTW, I am running full wing as well but didn't really notice understeer in 14. I'll have to check about the loss in straight speed as I can't have you pulling me down the back straight!