So I had a fun weekend at TWS. There were a number of minor issues with me and the car, and it certainly wasn't my best/fastest weekend, but I learned a lot. This weekend was the rare Clockwise direction there, totally new to me. The CCW direction I ran last time out there was much more of a "feeling" track where you could just traction-sense your way through it and rock around there in no time. This CW direction it seems a bit more technical and unforgiving, but it's still really fun to learn.
I left my USB stick at home and didn't realize it until I was ready to hit the Record button for the first session of the weekend. I picked one up Sat night locally and only got session data for Sunday. Had one true spin Saturday and an off-track excursion Sunday. Neither were particularly brutal, but I had to hop some tall kerbing getting back on the track from my Saturday spin, and I managed to bang up my FI mufflers a bit on the way over.
Tires / Camber
My tires are really hating my lack of camber still. They were already fairly worn down at the outsides when I started this weekend, and I finished them off this weekend. They could limp through another weak session or two, but no way I'm starting another whole weekend on them. It made the weekend interesting, because while I was learning the track better with every session, my front tire grip was also getting worse with each session. In the net, I think I peaked on the second session of the weekend and my times just went downhill from there.
On that second session I was probably running in the top 10% of the pack, and by the end of Sunday at least half the group was outpacing me while I adjusted down to the tires. About halfway through the weekend, I adjusted my rear sway and all 4 dampers to intentionally make the rear end slipperier (+1 stiff on rear sway, +1 stiff on rear damper, -2 stiff on front dampers), which helped balance the car back out to the front tires' pace somewhat. I didn't really like the very-understeery feel I was getting before that.
Really need adjustable front camber. I'd hate to tear up yet another set of fronts this way.
Transmission
No trans issues all weekend. Apparently the Motul Multi-ATF fluid works fine. If it didn't I'm sure the stress of the weekend would've made it apparent. The upsized cooler kept fluid temps in check and I never got into any hot/laggy shifts.
Brakes
Overall I was really impressed with the new brake setup (recap: CL RC6E front and rear, APRacing/Stillen BBK). I was peaking around 0.9g in the hardest braking zones without hitting any hint of ice-mode or engaging ABS. Zero issues with deposits/judder/etc. Modulation was even easier than the previous setup (CL pads + Stock calipers), which was already nice due to those CL pads.
My only minor complaint here is the design of the pad pins on those front calipers (CP7040 I think they are?). They only lock in via some dinky little snap rings. They're a pain in the *** to drive the lock ring into place (tapping in from the inside of the car), and they just don't hold very well even when they're pushed in correctly. I had both pins on the right front back out of the caliper on-track for me. They only backed out about half an inch, the outside pad moved a little out of position, and then everything kinda seized up in that configuration so the pin couldn't fall all the way out. I didn't even notice a feel change on track, but DR_ spotted it in the paddock afterwards.
Needs a better retention solution. Just letting the pins stick out the other side to install cotter pins like the stock caliper would probably fix it...
Cooling Changes
The new cooling config (25/9 oil, 19/6 trans, CSF rad w/o condenser, heater bypassed w/ 3/4" silicone, 80/20 mix + MoCool) definitely works as a configuration. My worst-case peaks all weekend were 225 oil and 221 water. More typical for most of the session time was about 220 and 216.
However, I still have a leak in the coolant system somewhere
The behavior over the weekend was that coming into the paddock after a run the overflow bottle would be fairly full of hot coolant, but after the car cooled down hardly any of it went back into the system. Then I'd open the rad cap and find a fairly large pocket of air in the system. Refilling that manually from the excess in the overflow tank got things back to a sane starting point for the next session, so I did that all weekend.
We're talking somewhere between 1-2 quarts of fluid displaced out to the tank and not recovering per session. Given that my water temps were reasonable during the session, I don't think the air bubble appeared until the system cools down and de-pressurizes, but it's drawing air from some minor leak at that time instead of drawing back fluid from the overflow. Preliminary diagnosis at the track (trying cold starts with hand-guestimate pressure-checking, smell, etc), it seems unlikely to be a combustion->water head gasket leak. There's no contamination to indicate oil<->water leak from the head gasket or water pump. Most likely I either still have a pinhole leak in the external hose connections and piping somewhere (perhaps a hose clamp that doesn't leak outwards at pressure, but does draw air back in during de-pressure?), or I have a head gasket leak at the edge from coolant to the outside world. I'm going to play with a pressure-test rig tomorrow and diagnose it.
Power stuff
The car definitely felt snappier on the the throttle all around. Engine/trans mounts, lack of AC compressor, and lower operating temps all contributed to that I'm sure. Taking a little weight out of the engine bay couldn't have hurt either. Hopefully I get time to gut the interior ac/heat stuff soon as well, and then start in on the cage/harness stuff.
Youtube of my fastest recorded lap at 2:10, which wasn't all that fast compared to what I should've been able to work up to, IMHO. I probably had a better time earlier in the weekend while I lacked a USB stick: