i'm trying to pin down what I can do to fix this. I know it's a truck, but on smooth highway, the minute i'm at 120 km/hr.. the think shakes like you wouldn't believe. Steering wheel, gas pedel, passenger seat, occupants. I had a leak in one of my tires and it's been road forced balanced. the tie rod has been replaced as well. aligment just completed. But the damn thing still shakes.

is this normal for our trucks? Are my expectations too high? It's the crew cab with 6.5 box, and LT truck tires that were optional at time of purchase. its' pretty smooth at all other speeds (save for the occasional oscillation over bumps). Just looking for someone to point me in the right direction!

 

My bro in law had the problem for weeks. They first said he needed new tires. Issue was still present but even worse then they balanced them and said it was good but problem was still there. He then took it back to same place and had that road force balance stuff done. Still had the issue so he took it to another shop and they balanced the wheels and it was perfect.

Try another shop to balance the wheels.

 

The tires need to be checked carefully for out of round.

 

Some of the earlier series 04-05 F150's had driveshaft issues...not sure if its related but just a thought.

Did you try multiple highways/interstates to duplicate the problem? I live in PA and there are some roads around here that just the right size tire will throw you into the truck grooves in our wonderful roads and you'll be thinking your car is going to fall apart.