frayed

Hey folks. New to the pcar world, though I have a fair bit of track experience with BMWs. I have long used a square setup on these admitedly very different chassis, so the 70mm stock stagger is a different world.

I'm sorting through street/track wheels and tire options, and want to stick with OE sizes and offsets for street so I can take advantage of factory spec N tires (I just mounted and, ahem, scrubbed in a set of S02A's and they feel great).

However, what have you hotshoes found on track? Have you had to move from stock sizing to get more grip up front? It seems a no brainer to go with MPSCs if the stock sizing works well on the track (I won't run Hooters since I tend to drive to/from the track on R comps).

And on camber, my experience is that with Mcpherson strut cars, *way* more camber is needed than what you can get on factory adjusters (mine maxed out at -0.5/side). Thoughts? Perhaps a well engineered set of camber plates?

MJR911

Jeff, I don't have direct experience with the 996s.... but I can tell you you'll want the biggest rubber possible. I have seen stock class 996s with 305x18 in the rear, but with full race suspension. For any of the R tires, you'll want more negative camber for sure.

RedlineMan

Stagger?

Did you say you had Oval Track experience? We have no stagger on Porsches... or BMWs for that matter. That is when you run different diameter tires on one side vs another to make the car naturally turn - usually only left - better. But... I'm being picky!

I would think you would want to track the car on street tires for a while to get used to the dynamics of the 911 chassis. Although you have all kinds of goodies to keep you safe, including 4x4, it is a slightly different beast than any BMW.

I don't have any direct 996 experience, but I would also think the OE widths would work fairly well for starters. You certainly might consider a wider front tire at some point, but that might also mess up the balance if you don't have a lot of tuning options to compensate with.

Finally, I have not seen a Porsche yet that could not get more than -.5 degrees of negative camber anywhere. Most of them have that much in stock trim. Again, I've never aligned a 996, but that doesn't sound right to me at all.

frayed

Stagger = delta b/t front and rear widths (maybe I'm mis-using the term, but that's how we always refered to it from the BMW side of things). I ran a square setup on my E36 M3, 255 Toyos or Kumhos all around. Stock on the C4S is a 225/295 fr//rr balance = 70 mm delta.

Yes, the most I could get is -0.5 at stock ride height. Of course, static camber will be increased, probably up to a degree or so, with nominal lowering. The stock adjusters only allow for minor camber tweaks to ensure that the fronts are in spec. At -0.5, it is w/i factory spec.

What I've noticed out of the box with this car is power-on understeer. It's gonna take a bit of lapping to figure this thing out, though I've been reading a bunch about rear engine/rear drive driving dynamics to help 'recalibrate' my brain. Given the amount of rear grip this car has relative to any car I've ever driven, it's hard not to get greedy with the throttle.

Brian P

-0.5 is w/i factory spec, but I'm pretty sure that you can get more negative camber and be out of spec. Granted, it might be difficult persuading a dealer to align a car out of spec, but it should be able to be done. I know the boxster (which shares a lot of front end parts with a 996) can get about -1 degree of negative camber. Sure, not much more, but it helps some.

Power-on understeer. Welcome to the fun of AWD.

Ken T

I think stagger is how Jeff defines it. I believe what you are defining is wedge. Any Nascar fans out there?

frayed

No. -0.5 is maxed out as I already stated above. The car was aligned by a friend who runs a performance shop (he specializes in setting up race cars for track use). That was the max we could get. He does all of my suspension work, from installs, to cornerbalancing, to helping nail down damping for track use. I used to do my own suspension work, but work/family duties dictate otherwise.

I avoid my dealer for the most part.

When I drove the C2 back to back with the C4S, I found more power-on understeer with the C2.

Brian P

Bummer, it's probably a similar situation that Boxster owners have. Some cars can get more camber and others can't. It seems to vary a bit from car to car. Also, it may have something to do with the AWD of the C4S - obviously the boxster doesn't share the same front end as the C4S.

ZBlue996Kam

I have a 2000 C2 and the maximum negative camber my shop can get is -0.6.

Bradskii

Frayed, I remember you from the M3 board. Anyway, I had coilovers put on this Spring, and unfortunatley, I found the same thing on my C4, -0.5 was the best that could be done. I went with MPSC in stock sizes and once I got used to the difference from the M, I really like the setup.

joey bagadonuts

I would agree with the suggestion that you track your p-car on street tires, first, before spending over a grand on Sport Cups.

Also, the kind of tracks you frequent should factor into your decision. If you come across a lot of tight, low speed turns (<50 mph) and you're having trouble putting down the power because your car ploughs through the corners, then a smaller stagger might be in order. On a wide open layout like Road America, however, you'll want as much rear-end grip as possible. There's really only one spot at this track where the car dips below 50 but plenty of others where the extra speed and centrifugal force encourage you to use as much rubber out back as possible.

That said, I use 225 and 255 tires front and rear on my C4. Like most newer 911's (89-on), the stock setup was 205/255 on 7 and 9 inch rims but I felt I needed to go bigger up front to combat the understeer. My car is a little different than yours, however, with its mechanical torque split (31/69 front and rear) and lowly, 250hp output but it seems most of the newer p-cars have a considerable amount of understeer dialed into them from the Factory.

What kind of bimmer did you used to drive?

frayed

Bradskii, yeah, I spent about 4 years on bf.com, moderating the track section and M3 section. Learned a lot about cars in general and about tracking. Hope a lot of it transfers over to this newfangled rear engine thingie. Thanks for the thoughts. Do you find the car too push much on track with such little camber? I found that you can actually feel the front end get light the rear heavy, and the only thing that bothers me is that depending on how aggressive you get with the loud pedal, you can push it into understeer. My friends here who are experienced with Pcars in general believe its more a matter of changing some of my habits to accomadate the new chassis, like, getting more rotation out of the car at turn in and through to apex, followed by a bit softer throttle ramp up once rotated.

Joey, I'm mainly at TWS in College station. A high speed track with only a few slow corners (2.9 miles, 15 turns), though not as wide open as Watkins or the like. I already have MPSCs on the way and some track wheels, but will go my first weekend (or open lapping day) drifting around the track on my street shoes. My car before this (which I still have) is an E36 M3. A wonderfully entertaining car, though from a chassis perspective, not as refined or as communicative as the Pcar. I'm in love with the ridiculously exacting steering the C4S is endowed with. Absolutely smitten.

RedlineMan

For the record;

Stagger is using different (larger) diameter tires on the right side of an oval car than on the left. This causes the car to naturally turn right. They do this by overinflating and stretching the carcass of the tire, measuring it, and keeping various diameter sets around for chassis tuning. Sounds high tech, I know, but it works.

Wedge is quite a misnomer; a term used in a blanket sense to describe jacking one corner of the car for increased/decreased preload. You will hear the term "a round of wedge" used, which means they turned the jack bolt up or down to increase or decrease spring preload. Wedge probably comes directly from them using spring rubbers or spacers to raise the rate on that spring by effectively making it shorter.
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Bummer about the camber, and I'm surprised. Guess I'd be going after the shock towers with a die grinder to round out those holes a bit! The Cup Cars use between 4-5-6 negative, so it can be done. There may be adjustable/different control arms too. I'll have to look!

The 964 AWD cars had horrendous amounts of understeer. The 996 probably less because they are not electro/mechanical and are less front heavy. Most of the time you need a more aggressive rear bar tightened up a bit to compensate. That and driving them more like a FWD=er helps. I would think you will have to learn how to rotate the car as suggested previously by being a bit more "assertive" with your turn ins. Toss & Catch is the 911 way!

I think you're going to be having fun!!

frayed

Vestal? Isn't that by Binghampton? Undergrad for me was Alfred University, before escaping the rustbelt. Instead, now I melt.

Toss & Catch. I see you guys have categorized and documented aggressive Pcar driving well enough to have developed industry standard nomenclature for your habits.

Time to talk to vendors about camber plates. Y'all have any suggestions on a camber plate? Does anyone make a street/track setup that still leaves in place a compliant bushing or two? At least on M3's, solid bearing camber plates tend to be pretty harsh since the camber plate is a load bearing point on strut front suspensions.

Cheers.

Bradskii

I know what you mean about the understeer. I did my first two DEs on street tires and stock suspension and felt a lot of push and was somewhat disappointed. I put the coilovers on and changed my driving style somewhat and am now having a blast. I do think the change in driving style from the M3 made the biggest difference. Allittle slower in, faster out is the mantra.