Thanks 762 and Sirbunz. What you guys said goes along with what I thought. Looks like it's Dunlop's for rain, and cool weather unless someone has something good to say about the Toyo's.
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I tried the 245/35R17 R1Rs on 9" wheels thinking it may be ok, but the car was "slithering." You can feel the soft side walls and tread to the point that the lag and recovery of the tires made the handling feel "slithery."

slithering - present participle of slith·er (Verb)
1. Move smoothly over a surface with a twisting motion. 2. Slide or slip unsteadily on a loose or slippery surface.

R1Rs just cannot handle the weight. The MX-5 is probably just barely marginal on R1Rs and the S just overwhelms them.

 

Thanks Random, good info. That's what I was looking for.

 

Here's my 2011 Nationals setup that helped get me 6th place and top time of day on the west course. It's unorganized and will input into the spread sheet that 762 started.


Penske 8100s with stock top hats
8" 850 front/ 8" 750 rear springs, take up springs in the front with divider
Comptech FSB on full stiff (estimated 850 lbs/in)
MX5 RSB
Ride height is about 12.25"F/12.5"R hub center to metal fender edge
Alignment is -2.7F/-2.5R camber, 6 deg caster and 0" toe front and 1/4" rear toe in
K&N FIPK
PLM Header
Home made Berk like HFC with short bung (no cell fix)
Stock cat back cut at Y with down pipe (measured 97 dB on west course)
255/40/17 RS-3 on 6ULR wheels
Mobile1 10W30
Mobile1 75W90 gear oil in diff
Honda manual transmission oil
Home made oil catch
fuel at 4 bars above half tank at start of each day
2675 lbs with no driver (1/2 tank)
Corner balance with driver

There are images of a lot of this stuff at My S2000 Page link in my sig. Look under STR Development.

 

I think it may be opposite

 

I would be shocked if you are right. Anybody have an Ohlins dyno?

 

My observation of the dunlops vs the kooks is that the kooks can handle more front bar than the rears without understeering...
Actually, in general my car is more loose on kooks than dunlops all around. This seems to be opposite of some of you all's observations.

 

Interestingly, what initially led us to a stiffer swaybar setup was testing while on Dunlops. However, even on them, both Mark and I agreed that the car wasn't handling 'well' by our definition (based entirely on perceived balance and feel.)

Mark and I do not have a similar style of driving, this was especially the case at the beginning of the season with him coming from an ST Civic and me from a Street Mod Evo. The fact that the car works for both of us (and Nick) is probably a product of our attempts all season to get it to feel 'good' subjectively, to both of us.

If your car is predictable and easy to drive, don't mess with it unless it is way off the pace. Mark and I haven't changed the car's setup for quite a while, at least a couple months (a long time in the grand scheme of developing the car in less than 10 months.) I would encourage you to *try* softening or disconnecting the rear bar, and softening the front bar to keep a similar front/rear bias but with an overall softer roll rate, and datalog it. In theory (though not always in practice) a swaybar should reduce grip overall. Obviously there's a limit to this.

One more observation: on softer springs (I think we started with 800/650) using very soft swaybars resulted in the car feeling really slow and sloppy through transitions. It has slowly lost this 'numbness' as we've changed springs, tested and retested shock settings, and gone up in total roll stiffness.

I hope my thoughts aren't too scattered or hard to read - I'm not very good at writing things down as I go, so it's all left up to my memory. And that's a scary thing.

 

I don't have much A-B testing yet but what you say makes sense given the known traits of each tire. it's obvious that the Dulop has better longitudinal grip and the Kook has better lateral grip. When the rear tries to put power down, it can overwhelm the longitudinal ability of the Kook and this manifests as oversteer. When the front asks the Kook to turn, it can.

 

Well I have already gathered something interesting from looking at the spreadsheet for my set up vs everyone else. It seems that most people have a relatively similar setup, but the biggest difference between my setup and others is tire pressure.

Most everyone seems to be running around 36psi in the Kooks, and I have been running 28psi. The car has felt great like this (kept up with Rockefeller at 1st AZ local event), and it does not roll over onto the sidewall.

I suppose this weekend I can try the higher pressure, but it is my first event at a new surface so that hardly seems like the ideal time to sense the difference in pressure.

How did you guys come to running that much pressure?

 

Could not agree more.

The car was magic, and did everything at the limit you would want and expect it to with a textbook driving technique. Seriously, there is nothing I would change about the suspension setup of the car. A great balance between transitional stability and sweeper balance. It forced you to be delicate with throttle application, but if you are comfortable doing that, it was like wielding a Hanso sword in the handling department. It was awesome. If it works out with me and Justin Lau locally, I think we are going to pick up and AP2 and replicate the setup to a T, with some only very subtle tweaks to accommodate the AP2 rear suspension geometry. Just set it and forget it, drive it all year and have a go at Nats again.

Again, absolutely fantastic job with the car Chris and Mark.