Stage 2: spin city
End track-hours: 30-something
End Laguna Seca time: 1:50
End parts/specs:
Pagid RS29 brake pads
-2.2 F camber, -2.2 R camber
RE71-r tires: 235/40/18 F, 265/35/18 R
Forgestar F14 rims: 8.5x18 ET40, 9x18 ET40-high
Eventuri intake
lots of front rebound dampening
So, into the summer of 2018, I was pushing the MP4s tires a bit too much and it was time for a dedicated track set. I was still going to the shop that did the KW suspension, and they recommended Bridgestone RE-71r, which have been kind to me since(*). As people here know very well, our cars need deep-offset wheels and finding these isn't particularly easy. After some searching around, I found Forgestar, who make flow-formed wheels with custom offsets at a pretty reasonable price. 265 tires at the back seemed to be the max people here had done, so eventually settled on 235/40 and 265/35. The distributor I talked to convinced me to do 9" at the back instead of 9.5" and that "the experts at Forgestar will take care of the offsets". Fine.
(*) I've gone through many (20?) sets of RE-71rs on this car. Pretty much everything about them has been said already, but let me recap in short: awesome levels of dry grip; gets maximum grip very fast (2-3 corners); gets greasy / overheated fast too (2-3 laps); max grip on our cars seems to be ~34-35 psi hot; when new, tolerable in the wet. Also, stay away from the 285/30/18 size on our hefty cars (see "stage kaboom" later)!
Sticky tires without better brakes didn't sound fun, so I also grabbed myself a set of Pagid RS29 pads. They seemed to be the default track pad for our cars (and the F8X). In hindsight, after going through a few sets, pretty happy with them overall. The fronts tended to last about 6-7 track days, as long as you don't overheat them too much. The release characteristics are the best I've seen in a pad, great for trailbraking. They didn't handle overheating well though -- the edges tended to crumble a lot and the pad could crack through the middle. Oh, and as any track pad, they sound as subtle as a freight train when cold.
The day after I got the wheels and pads, I tried them out at Thunderhill. Stayed with this setup through the summer for another 8-9 days (~15 hours).
To state the obvious, there was lots more grip and times were getting down. But It was a little... sketchy... Quite a few times losing the rear, a few spins, some tank slappers, the whole nine yards. The scariest one was probably losing it going thourgh Riverside at Buttonwillow (in reverse) at 90+ mph. Fun times. Good thing I was only going to tracks with ample runoff at that point, where you have to really try hard to hit a solid object. The worst of it was caking the interior with dust and collecting sand / small stones in various nooks of the undertray or the suspension. And soiled pants, allegedly.
My track friends were of course, giving me a hard time, talking about fidget spinners and things. The consensus was my issues were because of tracking a car with an open diff and soft bushings. The usual: all power to one wheel, plus bushing deflection makes things rather unpredictable. There was probably some of that, but honestly, I just wasn't that good at catching the rear and anticipating slides. It probably didn't help that these were my first few times with sticky tires -- which generally give you way less warning than street tires, and lose grip more suddenly.
There was another thing too. I hadn't had adjustable coilovers for too long and I was still experimenting with the various dampening options. Which mostly meant setting the front rebound higher and higher, because (i) it's the easiest to feel and (ii) hadrer's more racecar, amirite?! I actually wouldn't figure out that I'd set the rear up too loose and snappy until way later -- once I'd forgotten to restore the softer shock settings from a wet day, and the car felt way easier to slide around on the dry too.
Anyway, it would take me a while to figure that out (and a lot more time in iRacing to get better at catching slides), so I went with the most obvious thing and started thinking about a limited-slip diff and solid bushings.
Oh, also around the end of that period, I put on an Eventuri intake. Because you can't go wrong with carbon fiber! This was a bit against my philosophy to keep the engine completely stock[*]. But I'd just spent a few weeks on a death march at work, nights and weekends at the office, so I wanted something nice and blingy dammit! Reason be damned...
[*] It's pretty clear the car isn't exactly lacking power from the factory, and I'd much rather have reliability and lots of track time to improve the nut behind the wheel. This B58 so far has made it to ~120 hours on track with only consumable changes, which still continues to baffle me. Some (very small) problems are just starting to show, so maybe time to refresh it soon...