It's very difficult racing on a ps3 controller with all assists off. My question to you DS3 users, just how do you manage to race effectively on a controller? Maybe it's time to buy a steering wheel.
Recently I've been using a DS3 and I manage to race successfully with all aids off (and controller steering response set to 6 + real grip reduction).
I steer with the left stick, brake/accelerate with the back triggers (left = brake, right = accelerate) and shift gears up and down with respectively the X and Square buttons. I also occasionally use R1 for the handbrake (often useful as an emergency "turn" control in tight curves, for example Curve 1 on London Short).
In order to be able to brake without the ABS you need first to set up a front biased brake distribution. The usual choices for me are 5/2, 7/3 and 9/4, which all represent a 66.6/33.3% brake distribution. Lately I've come to use 7/3 which means that with comfort soft tires on most cars you will lock front tires at about 60-65% of the total brake trigger pressure (on a flat road and no extra aerodynamic effect). Keep in mind that tire grip might vary depending on many factors and it's important that you are always able to lock them to be sure to have the maximum stopping force at your disposal.
When braking, I usually press the left trigger almost all the way down, just above the tire locking threshold (this varies depending on the total brake force set up), then I immediately modulate pressure by quickly releasing it to what to me seems the ideal grip threshold. This, again, might vary dynamically depending on tire grip.
A trick for increased control is to use the "bumper" view. From there, thanks to the big dials, you can see very clearly the red and blue bars representing brake/throttle controls. They are a very important reference point, especially for braking. Another one (especially, again, for braking, which is kind of tricky to master) is paying much attention to tire noise.
Yep, I also have reassigned accel and brake to the right analog stick.
In that way you can't do "left foot braking", which can be a very effective manuever with the ABS disabled.