[Originally posted this to the V6 specific handling section by mistake. Reposting it here.]

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.

 

Nice report and video.

At TWS I upshift and downshift twice per lap. Since I learned to drive in an automatic tranny car, left foot braking is second nature to me. So I've recently tried to use that to my advantage. Since I only have to downshift in 2 out of 15 turns, I have started left foot braking in the other 13. I think it works very well to settle the car down especially in the fast corners.

One question: 2.7deg neg camber with the FRPP springs? Wow, that seems like a lot. Have you checked tire temps or wear at the track?

 

Thanks very much for sharing with the group.

For the gears you might not want to go higher than 3.55 which is what I am running. If my memory is correct Argonaut is running 4.10s and wants to go down to 3.55s as he is running out of revs. In my case 3.55 at 6000 RPM is 130 MPH which seems to work out well. Of course it depends on which tracks you normally run at.

Further to houstonnw's comment about the -2.7 camber how do you find it for stability under braking? Is it 'darty' on the street? My car is a DD I've been running -.75 this year and was thinking about trying -1.5 to -2 next year.

Must be real nice being in Calfornia - I put my snow tires on last week Of course I am not sure I could afford to run track days 12 months a year!

 

The 3.55s would probably work well at Thunderhill. With my tires and unmodified drivetrain I'm topping out at about 120 MPH down the start finish straight in 4th before I have to brake. But, part of my problem is that I have to hold it at the rev limit in 2nd until I finish the last turn and it feels like I'm leaving a lot on the table by doing so. After all, they say that exit speed out of turns leading onto long straights is the most important thing to get right.

As for the camber, yes, I used a tire pyrometer at this event and found that I'm probably running a bit too much camber for the track. On the autocross, a large amount of camber has worked well. On the track, I measured about 5 degrees cooler on the outside of the right front with the middle and inside being identical. I measured about 8 degrees cooler on the outside of the left front with the middle and inside being identical. I chalked up the right-to-left difference as being caused by the fact that we were running the track CCW; there were more left turns than right turns. However, I was never able to measure the tires immediately after a hot lap, we always had full cool-down laps which tends to mess up the accuracy of the measurements. I also used shoe polish on the tire shoulders and found that it was rubbed away right up to were it was supposed to be. The one thing that amount of camber allows me to do is to run my tires a bit lower on pressure than I otherwise might without experiencing rollover. In my experience, lower tire pressure tends to increase grip, to a point.

As for braking with that much camber, I don't notice any pull or instability under braking on the street or track. I run a very tiny amount of toe in which may help with that (just guessing here). I took the car to a well respected race shop for the alignment and they spent a great deal of time driving the car after each change to make sure that it didn't have any issues.

2.7 degrees is definitely enough to wear the tires more on the inside, I can see it already after about 1500 miles. Most of those miles are street driving to/from events so it's not too surprising that they're wearing on the inside. In fact, running it on the track has cleaned up the tires remarkably well. I think I'll just have the tires flipped on the rims this summer to see if I can get a bit more life out of them.

 

Yep - 4.10s are not the best gear on most tracks - unless it was a really slow, tight track. I just switched to 3.73s, will have it on the track next weekend. I contemplated 3.55s but I love the "punch" of the shorter gears coming out of corners and thus am hoping the 3.73s are a good compromise.

I've heard great things about those Direzza's from several folks. I just wish they made them in 275 size. Like you say, putting R-Comps in the back seat is not fun.

I've always run my D-Specs harder in the front than the rear. Hmmm...doing a two day next week, maybe I'll play with them a bit.

Thanks for the report.

 

Use the "blues" in the rear as well. It will settle the car down under braking .

I drive to the track on my NT-01's. They're D.OT. approved. F throwing them in the back seat.

3.73's have worked best for me.

Have you met Steve Kane? He runs in TT up there in NorCal. I don't know what color his S197 is. Were you out with NASA? If not go to a NASA event up there and find him. Maier racing has been working with him on his car. He can help you out.

 

I've driven on NT01's from Seattle to Laguna Seca and back (2000 miles on the freeway and 3 track days). And many round trips to Thunderhill (1400 miles). It's a myth that you can't drive to/from the track on R compound tires. One guy recently drove from San Diego to Thunderhill on Hoosiers! I wouldn't do that simply because they are so soft and you'll wear them out too fast on so many miles. But, the more street friendly R-compounds can be driven on the street. In fact, both Porsche and Lotus sell street cars that come with R-compounds from the factory.

Thanks for the video, nice smooth driving.

 

If and when I spring for a tire pyrometer I would plan to come into the hot pits during a session to check tire temperature.

 

looks like a fun track. i did corner work for TWS this past weekend and am looking forward to getting out there. i may be doing a work/drive on the 8th-9th, i'm really excited.