Setup help: Lotus Evora GTC oversteers and crashes approaching downhill turns at Nordschleife

[Ken Tegrum]

Unfortunately when I ‘panic brake’, i.e. applying 50 to 75 of braking power suddenly, long before turning into a corner, the car will just spin out on corner entry.

I used a setup heavily sourced from Zandvoort.
Image of the setup used at Zandvoort in an Excel spreadsheet:

Nordschleife setup:


The oversteer is very common at downhill curves, especially at Kallenhard, and Ausfahrt Breidscheid.
I’ve included two video clips depicting the spinout at the corner, with the pedal inputs at the lower right hand corner.
https://gfycat.com/EnchantedSingleCarp
https://gfycat.com/somefavorableanemonecrab

The reason the recording is ‘laggy’ is because OBS wasn’t configured properly on my end.

I’ve also included two different excel file as well as the AC ini file from ‘My Documents’.
The xlsm file features a macro to duplicate the conditional formatting (color) from cell H7, to the cells specified in cell A54.
https://drive.google.com/open?id=1zAuIbtVrLOmEjHc-DniOF4ciyIq4ANtm

 

[RasmusP]

I don't apply throttle under braking. I remember this being discussed and me checking if I was doing this, even subconsciously, I could have...but turns out I don't. So it's not a necessary thing. It is very helpful though to be aware you can settle the rear down mid corner with a bit of throttle.

When I'm comparing my latest qualy lap which I was very happy with vs the lap I spun (from my video), the telemetry, when perfectly synced on distance (so same spot on track), I really can't find the difference that decides about losing the rear or not.
Maybe you see the crucial difference?
Coloured is the good lap, white is the spin-out lap (you clearly see which one crashes hehe). What I see in that picture:

Good lap:
- lifting the throttle later, braking a little earlier. Slight overlap on the pedals
- starting to turn in earlier although that matches with the earlier braking
- turn in rises a little bit slower and only goes steeper again when throttle is already applied again
- throttle is applied while I'm still feathering the brakes although that's really not much

It's really not such a big difference but on track it decides about spinning out without a chance or being totally planted through the corner. I think it's the more gently turn in combined with earlier throttle to stabilize the car like you guys say. It's not really "applying throttle under braking" but the transition makes the difference.

Anyway, what do you say to this? Same car, same track temp, same setup etc!

 

[Kek700]

It was the done thing then to do all your braking in a striaght line. because the whole
point was to provide as flat and stable front platform, if you got it wrong and started to turn
sooner than you intended with a heavy loaded front axel and very stiff rear, especially when
conditions we’re slightly out of your favour, you had an instant spin.
I got into the habit of constantly modulating the throttle, if nothing else, but to catch a spin.
I still think that this is the hardest oversteer to catch, ( probably limit ability did not help ),
there is no real warning. It seem to happen when your mind is focusing on other things.
I am not saying that an aero single seater is not also in that bracket. Its probably more expected.

 

[Kek700]

@RasmusP .Did notice in your video that the spin only seem to occure when you went from a
higher speed to the same point. If you narrowed that down and turned at a lower speed you did not spin.
Sorry about the simplicity, but so much else is happening it’s probably not helpful.

 

[PhilS13]

Anyway, what do you say to this? Same car, same track temp, same setup etc!

The pause between brake and throttle is the difference. If you have yaw rate channel it sometimes will tell you when things start to go wrong.

 

[RasmusP]

The pause between brake and throttle is the difference. If you have yaw rate channel it sometimes will tell you when things start to go wrong.

Damn I didn't think about looking at that channel.. I'll come back with inputs + yaw rate comparison
And yep, the short pause combined with still further steering angle seems to be the crucial bit. It's amazing how precise the human inputs can be and how much difference they make. Honestly watching the videos side by side at 1x speed I don't see a difference apart from the green bar flashing on earlier and in one video the rear just throws around...
I'll see if the yaw rate channel gives more details!