So you ran 38-40 hot? Idk, maybe I was as high as 38, but I thought it was working better (less push) at 35-36. But I am by no means an expert in this area.
I'm wondering if wasn't able to get them consistently up to temp due to traffic? There were 2 sections I was pushing way more than I remember with the Dunlops, which I wasn't happy about, but I reasoned it was due to the full depth tread squirm.
What's your suspension set-up? Sounds like a stupid question, but how bad does you car understeer?
Yes, I had to run 38-40 hot to keep them from rolling over too much. I pretty much erased the little arrows that tell you where to keep the wear above on the sidewall. What size tire and wheel? I tried a few different temps and found this to be the best for this tire 255/40/17 on 17x9 for my car. Any lower than 38 hot, would result in sidewall wear, and a sloppier feel. I really wish the RS3's had stiffer sidewalls. Haven't run the Star Specs yet, sorry.
If you had got them up to temp, then caught in traffic, I'd expect they were still plenty warm. Unless you got behind a bunch of Miatas running parade laps. Hate that.
UNDERSTEER!?!? It's a nose heavy Mustang, of course it understeers. Been great for learning! It was really bad when I first got the car (prepared by who knows, but had all the safety gear I wanted). Front had Griggs/Koni DA coilovers 475#, and that huge Steeda bar. Rear had Bilsteins and their matching BTS springs (SOFT) on MM LCA's and MM PHB. It also has Full length SFC's and tower braces front and rear. It had a REALLY bad push then.
Then I met some guys racing sn95's who shared their setups. One was running MUCH softer 350# front coilovers and 250-275# rear conventional springs all on custom valved Bilsteins. Had Bullitt sway bars (barely different from stock GT) and MM LCA's and PHB. He won his TT class both days and another free set of Hoosiers with that... Like he always does.
So I opted to try softening up my front with a stock GT sway bar... (free and easy) No where near enough of a change!
So I added the fwd offset control arms + X2 balljoints in hopes of adding some front grip. Definitely helped a bunch. Way more noticeable than the sway bar change. My confidence grew, and when I found a lot more speed, I still had a ton of corner entry push... just at higher speed than before.
So I found some 400# Hypercoils to try out front. Also got some H&R race springs for the rear. Sent my Bilsteins off to be custom valved to match. Still using the Koni DA's up front... with this setup... HOLY crap! The car TURNS! There's still a little push, but I'm comfortable with that for now... still learning. There is a bit more body motion now... Of course I also moved from the Sumitomo HTRZ III's to the RS3's, and the added grip I'm sure is forcing the suspension to do more. I'll be trying some of those Grand-Am Cup tires in a couple weeks, so we'll see...
From here I'm probably set with this car. I'm just getting track time with this one until I feel comfortable moving into the Bullitt, and building it up from there. Were I going to keep the Cobra, it'd have the 5-link going in next for sure...