zero2sixd

Finally had a chance to get the car back to Thunderhill (Northern California) in late September and thought I would report back on a few of the modifications that have been recommended on this forum.

#1 Brakes. The last time I was at this track the car was bone stock (18" wheels with the BFG KDWS) except for the brakes. The brake upgrades included SS lines, Hawk HP+ and ATE SuperBlue fluid and they were *inadequate* for my skill level combined with this track. I was experiencing fade by lap 2 of session 2. This time around I added the Agent 47 brake duct kit and Hawk "blues" up front (kept the HP+ in the back). I was pushing the brakes as hard as I could this time with absolutely no fade. I was standing on them so hard in two corners that I would sometimes have trouble getting the down shift done to my liking (sometimes too early, sometimes too late). Need more skill development there..

#2 Tires. I ran the Dunlop Direzza Sport Z1 in 245/45 R18 this time and found them to be good at communicating at the limit. FWIW, the KDWS was also good at this, however, it had nowhere near the lateral grip of the Z1. With the Z1 I've measured 1.1 G on an autocross course and I had to be near that at the track. A number of people were pretty impressed with the speed of the Mustang through the corners with these tires and they have been wearing very well. R-comps they are not, but then I have never really bought in to storing and transporting an extra set of wheels/tires. One caveat here for anybody thinking about using these on their DD, they are *loud* at anything above about 45 MPH.

#3 Springs/Dampers/Sway Bar/Camber. Over the summer I drove in a number of autocross events and used that as an opportunity dial-in the car. The car is on the FRPP (aka Eibach Pro-Kit) springs, D-Spec dampers and Steeda rear sway bar. It has about 2.7 degrees of static negative camber using the MM caster/camber plates. Normally at the autocross I set the D-Specs to 4 turns from full hard in the front and 1 in the rear. Frankly, I was a little worried that since I had spent so much time autocrossing the car it would be a little too eager to rotate at the higher speeds found on the track so I set the dampers to 2 turns in front and 2.5 in back. This seemed to work well and I didn't play with them from there. (One note here, as Sam Strano has stated before, the D-Specs settings *do* move over time. I found the right front kept wanting to move toward hard. At times I variously found it anywhere from 1.5 to 1.75 turns from fall hard.)

Here's a YouTube link to session 2:

http://www.youtube.com/watch?v=7YD7z5QSz9w

FWIW, my line and exit speeds got a lot better later in the day but this session filled up the flash on my camera. Next time I'll bring a laptop to download it after each one. If you're interested in hearing a Cayman S go by at full song, that can be found at about 6:01.

Next on the list is 3.55 gears, maybe even 4.10s, the 3.31s are just too tall for the track, though I didn't necessarily mind the lack of shifting required.

Norm Peterson

You might end up having to choose whether staying in 2nd at autocross or if in road course use avoiding 5th is the more important criteria in making your gearing choice. Even 3.73's might be a little short with 245/45's at a wide-open auto-X unless you've got a few more rpm available than OE for the GT.

I may start wishing that those Dunlops came in 255/45-18 . . .

Edit #2 - did you intend to post this in the 4.6L handling section? FWIW, I'm not sure that two separate handling sections are really necessary, and the available modifications tend to be pretty much the same anyway.


Norm