The retarder is part of the gearbox. Both brakes are only directly affecting the driven axle (s), so your truck might become unstable if you use them without the service brake (brake pedal) while turning or on wet roads. In my opinion the engine brake isn't really needed in the game because the map scale is so small.
In in-game setting it says always joy 2 when i set the wheel axis etc. It says in the tutorial that u can have both the "keyboard + vJoy Device" and your controller selected as controls in-game. However inorder to get it to do Joy Y and not 2Y is to simply not select your controller as a input method. #14. Showing 1 - 14 of 14 comments..