I have a 2004 F150 that shakes at 70+/- mph. A little history: whent the truck was a few months old a trailer came off the hitch and hit the left rear wheel. The tire was replaced and the wheel inspected. In 2006 my wife hit our retaining wall and knocked the corner out of it and denting the entire right side of the bed. I assume that the right rear wheel hit the wall as well. By this time there is 60,000 miles on it. I noticed the shake around this time.
I replaced the tires when multiple attempts to balance the old ones failed. I must also note that the year before this I was out of the country so the truck didn’t get used which also led me to think of the tires.Since then I have had two dealerships look at it as well as my own investigations.
Any ideas?!
Have someone in another vehicle watch the right rear tire as you drive the truck down the highway, and see if it is constantly rebounding after hitting a bump in the road.
If yes, then that is a dead shock (you could always unbolt the shock, and see if it collapses, or if it springs back out like it should).
If the tire isn’t oscillating after hitting a road imperfection, then you are most likely looking at a tire/wheel imbalance, or an issue with the brake or wheel bearing in that area. Warped rotor can cause a shudder at higher speeds, and so can an out of round tire/bent wheel.
BC.
You may need a good local suspension shop to take a look at it. Don’t look for a national chain to do this work.