I put a pair of 295 Yoks on the rear as a fit check and went to my local TAC 6 event with no other changes, including the same tire pressures. It was a disaster, but at least the tires fit!

Way too much oversteer tendency meant that I could not aggressively trail-brake into corners without losing the rear end, which I proceeded to do time after time. If I beat people that’s usually where I do it: on corner entry. I placed a disappointing 4th in C-Street and 22nd overall of 114.

I learned a lot by comparing my data to the winner of CS who was kind enough to give me his data. In return I created a set of charts analyzing the differences corner by corner. Besides my driving mistakes, the data showed that the Cayman has a very slight acceleration advantage over the ND Miata in both 1st and 2nd. Meantime, the Miata seemed to have a slight grip advantage, but that may be due to the limitations of the Cayman oversteer situation. At least I hope so, because this entire enterprise is predicated on the Cayman having a grip advantage inspite of its weight. It may be that I’m running into the reality that lack of front camber is always going to limit peak cornering grip to less than the Miata.

The next event was with the Alabama Region of the SCCA at Barber Motorsports Park outside of Birmingham. Prior to the event I dialed in a healthy amount of toe-in in the rear to cure the oversteer. It worked. The rear was now super-stable and I won CS in front of two ND drivers that beat me the weekend before at TAC 6. I won by over half a second on a 43 second course.

It was too much toe (5/16″ total) because the car would now push powering out of a corner. This car had never done that before. It was also really hot. I had a co-driver (who will drive with me at Bristol) and we confirmed again that you can overheat Bridgestones on a hot afternoon with six runs if you don’t water early.

The Barber Proving Grounds surface is very smooth with consistently high grip. This meant that the present lack of damping wasn’t so critical, i.e. the car wasn’t bouncing badly as is likely to happen at Bristol.

Back home I fabbed a string setup in order to produce an accurate alignment. (I didn’t feel like leaving the car all day with the kids that work at my local alignment shop like they insisted. That’s two shops that can’t figure out how to make an appointment system work, so I decided to do it myself.) Initial results were that the front tires are both pointed to the right!

It took only a single iteration on the strings to get what I wanted. The car is now at zero front toe while straight on the axis, and 7/32nds (measured across 19.5″) total toe-in in the rear, split equally to each side and straight on the axis. (7/32nds = 0.32 degrees per wheel) I know that this is more toe-in than most people use for these mid-engined Porsches. It may get reduced later. But, I like to be very aggressive on trail-braking into corners so rear stability when the rear gets light is needed, as least for my confidence. I’ve driven other Caymans with minimal toe-in and they did not give me the confidence I needed when braking hard while turning.

This is the setup I plan to run at the Bristol Pro-Solo and Tour later this month.