i have an 03 cobra convertible that starts to shake,body and steering wheel,at about 50 -60 mph and then gets better as you go faster.i have force balanced the tires and checked for susp. looseness.grabbing frt wheels and checking for any movement.would a wheel bearing possibly cause this.it is very strange.seems more severe at times and mild at others.i'm confused.the car had been hit in the left front by the previous owner.but all was repaired including a new wheel and l/frt wheel bearing.any ideas?thanks i'm a new guy.