Just to report i added this { ffb_force="3.0" ffb_friction="1.0" } to the g920 line and it fixed my ffb. Now i feel bumbs, car weight and colisions.
name="lg_g920" priority="100" type="wheel" ffb_force="3.0" ffb_friction="1.0" />
name="lg_g920" priority="100" type="wheel" ffb_force="3.0" ffb_friction="1.0" />