Rename core.ini.sample to core.ini.
Find and edit this line:
[ Joy ]
allow_force_feedback=1 ; Use FF if device has it
1 = FF on
0 = FF off
Try these values for FF also:
; force_feedback_damping=65.000000 ; force feedback damping
coefficient
; force_feedback_latency=0.0.00045 ; force feedback latency (secs)
; max_steering_torque=150.000000 ; steering torque in N*in giving
max device force
Good luck
Gerry