What car are you using and the steering feeling heavy? The default Lamborghini Murcielago?
Really the FF sliders in the controller set up screen should work, but I've never been a fan of the controller set-up in Racer, it seems to never be clear what is actually happening and I've ended up losing control configs or over-writing other ones etc.
Once you get things working right then check through the controllers profiles and find the ini file that contains the data you are using, then copy it and rename it to 'my controls'
You can then set that controls file in racer.ini and then edit it and *know* that it will work, without having to use the game controls menu again!
You can also load different controls in-game if you press 'tilde' key to bring up the console, then you can write "controls x.ini" and load your desired controls file.
Ie, I run a mouse and my wheel separately, one is called mouse.ini, one is called wheel.ini. It's quicker, easier and safer to load/edit these files in Notepad++ and via the Racer console than via the menu in my experience... again sometimes the menu just isn't clear and you end up over-writing your mouse controls with the wheel ones and other odd things...
Cheers
Dave