for me sqaush ball works a treat.
1/2 squash ball behind the brake pedal - then go to the controller/wheel - advanced, and adjust the outer deadzone, to be where you want max pressure to be
the squash ball means, that you cant press all the way down, and increases resistence as you press.
i used a medium strengh ball, but i think harder might have been better, also doesnt have to be 1/2, you can use more or less, depending on how early you want to feel the pressure.