These are tricky to setup.
I've never found a safe/grippy setup for them (They're lethal at Le Mans when running no wing for example
), and the same applies here.
You can almost ignore the gearing, I wasted nearly an hour trying for better ratios - but the options in the 917 are so awkward I only ended up going slower.
You
can lengthen the gearing to make the cars safer on corner exit, but you will loose considerable speed onto the straights - it also has the effect of removing some engine braking, which is critical in these beasts if you actually want to stop
All I can advise is try to create enough stability that when the car moves around under you you feel safe and in control. If it stops moving under you then it'll be dog slow based on my own practice laps.
Also remember that the wings only affect the tail end of the car - max wing and you'll be very slow through T1 as you won't be able to turn. No wing and you'd better hold damn tight!
As for my own style in these - pretty much the same as always. Just with less sideways.
Braking upto and into the turns, balancing on the throttle through them and only flooring it when I know the car can actually make the exit.
For wings, my current fastest lap is with a moderate degree of wing - I can't be sure exactly what as I'm still playing with flaps Vs Wing angle, they affect the car differently and I'm still trying to find the best balance point.
I also still need to do a zero/very low wing setup to see how the car behaves - I'm expecting T2/3 to incredibly dangerous like that though.
You can expect roughly Jeffrey's lap time without touching the wings and through making only minor changes to the setup.