Damping

[feuerdog]

Ah yes,....my bad, wasn't thinking of the correct start/finish line.

Hmmm,...yeah, faster overall damper response won't help there.
Decreasing radius, steady-state oversteer can be solved a variety of ways,.....but given the other tuning situations you're trying to adjust for......

1. Lower front rebound by maybe .1 or .2
This will accomplish a few things, but basically the front end should still retain braking stability while improving acceleration response in the rear. Too much though and the front push more on initial turn-in.

2. A slight, and I do mean slight, rebalance of ARB's. Like transferring as little a 1 or 2 points from rear to front. If this unsettles too much of the balance in other areas, look to correcting it with a slight rebias of spring value from the front to the rear, no more than maybe 10lbs of transferred value.

3. If camber is good, and you do modify the caster as mentioned earlier, then you may have to make these adjustments anyways to rebalance the difference in caster(dynamic camber) grip.

But as you say, it's a high speed cresting corner, where throttle steering(already at the limits of traction) is common. Just like the Maple Valley Reverse downhill sweeper, a little throttle lift/modulation may be required to retain composure.

Elevation changes, crests and dips, are very touchy subject to tune for, even for a track specific tuning application.

[Fit4aking]

What a ride!!!

I took your advice F-dog, all of it.  The car is more stable now than it has ever been.  I dropped a full second off my initial time on Cat School, here's how:

-0.2 from Caster, I did one at first and it didn't feel perfect so I went for two and it got much better.  Then I set out to bring the rest inline from that setting change.

-0.2 from front rebound.  I was already down from my normal value of 8 but now it is at 7.7 front and 7.9 rear and it sticks great.

I took two clicks from the rear sway bar and put them back into the front stiffness, then took an additional click out of the rear as it developed a very repeatable yet slight push.  Problem solved.

I took an additional 5% out of the acceleration differential setting and I'm able to maintain speed in all the trouble spots as well as get in the gas sooner.  I'm ahead by 7mph on the straight and as I said over a second faster per lap.  Thanks for all the words of wisdom, they helped!

[feuerdog]

Interesting,....I didn't think it make that noticeable an improvement, but if it works that well, great.

I still have concerns though....

1. What was, is, your caster setting now? Was it in the 5.8 range ior higher?

2. You say the car feels "more stable than ever",....too me thats a sign of being slower, not faster.
Confidence inspiring yes, controllable yes, but only faster if driver smoothness is an issue, and I don't think thats too much an issue for you based on your detailed driving reports. Thoughts?

3. The real test of the tune now is to throw some other tracks at it and see if maintains that stability and response.

4. You lowered the rear diff. 5% may not seem like alot, but when tuning for a specific corner it has the potential to make a huge difference in handling. In FM the diffs are pretty much "locked" or not. If the diff locks mid-corner of that sweeeper then the result would be a break of traction,...a break further accentuated by the crest. Lowering the diff is the right direction to adjust though.
It's a RWD right? Is it lower than 50%?

[Fit4aking]

I was only expecting small changes as well but I think it was the sum of the parts that made the whole better.

1.  My initial caster setting was at 5.3, then I went back to 5.0, I'm currently at 4.8. 

2. The car feels more stable because of the adjustments.  It still gets the rear end loose but it isn't snap oversteer.  The additional turn in has increased entry speed, the rear ent stability has increased corner exit mph and the lap times are there to back it up.  I am able to drive it much smoother now that I know it is going to stick.  I was likely being conservative before as once it would start to go I had to work to get it inline, now all I have to do is loosen the throttle or lighten up on the brakes.

3. I hope to get it out on more tracks soon.  I spent the latter part of my evening in the paint booth, not running laps.

4. The car is RWD, torquey, and the diff is at 35% accel and 45% decel.  I could lower the decel value but I tend to maintain some throttle through a turn, only lifting to induce oversteer.  The replay of this car running on Sebring pre-tune is in my storefront for a clue as to how I pilot the thing.

I have a Dash-4-Cash tonight in B-class Range Rovers but once that is done I'll try to run a few tracks and see if the changes help elsewhere.  I hypothesize they will.

[Spiny Anteater]

...
2. You say the car feels "more stable than ever",....too me thats a sign of being slower, not faster.
Confidence inspiring yes, controllable yes, but only faster if driver smoothness is an issue, and I don't think thats too much an issue for you based on your detailed driving reports. Thoughts?

...

Just to add a little bit more to this (and it doesn't seem an irrelevant place to mention it), I decided to see how Bimmer's M5 B500 tune compares to the B498 one we were sent across for the 'Ring GP Time Trial.

My test track of choice is Catalunya National so I'm at the opposite end of the circuit to Fit, but it is still one where grip comes into play more than out and out speed. Running the two cars, the gift car felt way more stable than Bimmer's. I was convinced I was going to be faster than I was in Bimmer's, what with the extra confidence I felt and the apparant extra grip is was a no-brainer wasn't it? Well, no as it happens. I got Bimmer's car around in 1.19.647 while the gift car couldn't get below 1:20.997. Around an 80 second track, that 1.35 seconds is a huge gap for what are variants of the same car.

To date, that is the most dramatic proof I've come across that "stable=slower"