Tonight was the third track night I've attended with the RX-7, and the last one being held this year. I was really happy with the performance of the car, and I feel like I have it fairly well sorted and dialed in now.
After the last session (which was about 100F out and the first session I completed), the primary note I had was that the right front wheel seemed to be rubbing in hard left turn. Upon inspection, I found that its spring perch was significantly lower than the one on the left front wheel, and that corner of the car was observably lower than the other three. I raised it to match.
In the past month, I've also read a couple of books on racing - both involving driving techniques and also tuning techniques. And from that, I decided that I should try to push the caster of the front wheels further forward and also try some more toe out in the alignment. There's not a ton of adjustment that you can do with caster, but I made what adjustment I could.
Lastly, I wanted to run with more fuel in the tank to try to have more weight over the rear wheels. I may have ended up with a little more fuel than I had on the last session, but not very much more.
It was also a very different day - mid 60s and strong winds vs. upper 90s. That impacts everything - horsepower, tire grip, and then what drag or extra forces the car must either overcome or be helped by. I was also running in the intermediate class instead of the novice class, which had me as the lowest horsepower car by a significant margin, and in theory the drivers should be better. Unlike the two times in the novice class I ran, I didn't pass anyone today, except for that one Viper that spun out.
With all that said, the car performed very well, and I think that the changes that I made helped. There was no more tire rubbing on left turns, and the extra caster seemed to help the car's cornering as it should (granted at the price of some higher steering effort and more wheel turn required). I got a better hang of when I should be downshifting (it was too early) and got to the point of taking more corners flat out (which the car can do). I'm sure that these tires are now starting to lose their maximum grip potential, which negatively offset the other factors somewhat. However, I spent a lot more time in 4th gear this time around than 3rd, and had two straights that I got into 5th on (only the main front straight would sometimes see 5th before). Some of that may have been due to more horsepower from the lower temps, but I think that more of it was just being able to carry more speed through the corners.
Admittedly, the worst component today was the driver. There's been a lot going on this month and I've had a lot on my mind. My head wasn't fully in the game today, especially on the first run. I have no data acquisition, so I haven't been able to track my lap times, but my wife was watching for at least the first run. She said that she could see me closing the gap and gaining on cars in the corners, but then the gaps grew on the straights. End result, though, is I think the car itself is doing very well.
Now starts the time period of being able to plan for next year and make changes/upgrades over the winter. I believe that the power brake booster has a vacuum leak and is bad. When I step on it, there's a noticeable change in idle, and at least it seems to have a bad check valve as any vacuum goes away immediately when the engine turns off. I didn't replace the vacuum hoses going to the booster, but I need to do some more inspection and look into that. Potentially related is that when the carb is running on the primaries only, it seems to get lean and start sputtering, especially towards the top of the primaries throttle travel. Maybe it's a vacuum issue related to the brake booster. Fresh fluids are an obvious one. I also want to replace the driveshaft U-joints, more than anything because they appear to be original (making them 40ish years old). I haven't yet checked the ignition timing, and that's something that I need to do on the car, although I suspect it's fine.
From there, it's just a general inspection and decide what the plans are for it for 2023!