Well, I had an interesting day. First impressions, and then the issues.
- Camber plates: I was worried that the camber plates could go off-spec once I start hitting the bumps at the track hard. I marked the settings, and checked after every session. Nothing moved! It appears 20lb.ft on those small bolts are indeed enough to keep things in place.
- New alignment: It worked great! The turn-in right before the corkscrew is much improved, and the car even feels more stable in the sweeping turns. The tire wear was also even. I love it!
- Pedals: They worked great; ZERO mis-shifts! Okay, one mis-shift, but it was due my seat settings. Highly recommended.
- MPSC 2 tires: I set the temps to 26 PSI cold. Well, they worked. For 3 laps. It took about 1.5 - 2 laps to get good traction in the beginning of sessions, and then I lost traction once the hot temps started exceeding 33 PSI. A cool down lap or two, and then back to business. This experience is actually very similar to what I had with PSS; no wonder, they're from the same family of tires.
Anyhow, the fun began, once I started discussing what to do to remedy the issue. Since the tires overheat, I suggested I should bump the tire pressures to help support the tire and reduce the flex (and therefore overheating). A fellow driver, who was attending with an Exige, but has a C7 Z06 as well (on which he has experience with the MPSC 2 tires) suggested I should actually drop the temps. Since he has experience with this tire, I decided to just give it a try, and dropped temps by about 1-1.5 PSI. The result: it actually did improve the traction, and the tires' traction seem to have lasted longer.
It also caused this:
Per the Les Schwab right by the track, since the tires are low profile, the TPMS was 'spinned' or 'touched' by the tire surface, and seal is broken! With the pressures now at 24.5 PSI or so (cold), the sidewalls perhaps did NOT have enough strength. This might be true, or perhaps tires just way overheated, heating up TPMS too much, which made its seal lose its strength? I don't really know.. Please note the actual pressures I read has never dropped below 28 PSI (since the tires never really cooled down during tests), but the front tire was leaking when I parked at the paddock. I've never seen anything like this before, but I think the short moral story is:
DO NOT LOWER YOUR COLD TIRE TEMPS BELOW 26 PSI! I suppose GM knew something when they made that suggestion
Has anyone else ever had a similar issue? All 4 valve stems leak when touched and pressed upon, but the front left, which had 0.5 PSI lower pressure than others, was leaking even without being touched. I had to use painters' tape to push the stem in a direction where it stopped leaking to make it home:
Anyway, besides this issue, it was a fun day. My brother's Viper was way faster than my car, though : P
