The FD likes about a 1/2 or even 3/4 inches of rake. Or if the front is 25.25 inches the rear should be 25.75 to 26

I see way too many FDs with equal or worse a lower rear ride height than front which will induce push or slow you down.

 

I don't believe you are getting these HUGE improvements in lap time from the changes you are making to the car. This is from you getting more familiar with the track and better/more-consistent/faster as a driver! Fantastic progress
Are tire temps and pressures coming up a lot more now?

 

I am familiar with the track. I've been driving their for 5-6 years.

This was a different, much longer, much faster track, so the temperatures were much higher. The extra time came *mostly* from the car being much more stable (it was a shocking difference), but also from being about 5-6 mph faster in the straights.

I still occasionally get some anomolies but they tend to go away when I measure that tire again. OTOH, the longer the tire cools, the more even temperatures tend to be. That, and I occasionally write the temps down for the wrong tire or write them backwards...


My boost keeps fluctuating from about 0.5 bar to 0.8 bar (what it's set for). I guess given the same wastegate spring (set for 0.8 bar), that's naturally going to happen depending on the temperature and air pressure. But I'd much prefer it be consistent...

 

Measured where, though?

Dropping the rear (it was probably much too high) didn't induce understeer at all. If anything, it had less understeer because the stability allowed to be more aggressive in making the front tires work.

 

At the middle of the fender

 

great news! rear ride height can be PICKY, not only does it change the height, but toe and camber changes as well, so if you try a couple settings, it makes it easy to dial the car to whatever.

 

I suspect a little bit of extra rear camber probably helped in the corners. Shouldn't toe not change too drastically as long as rear bump steer (roll steer) is minimal and ride height changes are reasonably small?

FWIW my grouping was pretty good as most of my clear laps in each session that I didn't bungle too badly were within about second of each other (on a 3.7-km course).

I really need to get another alignment... as soon as I replace my bumper and fix my fenders.... Woops.