I know this is a bit of a ressurection and don't know if you guys knew this so here goes.
I found a workaround that seems to work. You have to TURN OFF soft lock.
And then if you enter a new car you check the visible max rotation of the in game car i.e. the golf f2 car has 540.
My logitech has a rotation of 900, but in reality it's more like 885.
If you then do 540/885 (the different rotation angles) it equals 0.6102
So you set the steering saturation to 61% (0.6102x100%=61.02%=61%)
This seems to work for me. It will engage the softlock when at max rotation of the car you're driving.