My car starts to shake above 60mph. Its weird because I know its not the balance of the wheels(had them checked) and the steering wheel doesn't vibrate as much as I would expect but its more like the entire car. I can feel it in the floor boards with my feet. Its speed dependent also because just cruising around there isnt anything vibrating at all just some side to side wobble in the steering wheel. The shaking gets really bad around 80-90mph. Any idea what it might be? Bushing? Steering rack? ball joint? control arm? Any idea what I can do to pin point it?

 

double check the wheel balance
check all your suspension...(ball joint, wheel bearing, tie rod)
check to make sure your rims are not bent
check to make sure the tire is not out of round or have any internal damage in it.
check your alignment also

 

Don't forget to check cv joints on the axles. My 5.5 does this, but thats bcuz its dropped so low.

 

alright thanks guys