I'm clueless with this one.

While driving at highway speeds, my truck will sometimes vibrate violently in the front suspension somewhere....

I don't know where to start looking for a problem, because it's only happened 4 times in the last 3 years, but everytime it happens, I think it's going to shake my truck apart.

It almost seems like when this vibration happens, it seems to resonate the faster I go. I pull over, stop for a few seconds, and the vibration is gone when I resume driving.

Any ideas what this is?

I looked thru some TSB's and found a couple of them online that claim a vibration problem at highway speeds, but no specifics on the problem.

 

Possible that the emergency brake is sticking?

 

only once and wile wow have you looked in to the bearings? and is it a 4x4?

 

mine does this too, its not crazy violent but still its very random and when it does it it gets worse when i brake...ive been wondering what it is too

only thing i can think of is a caliper

 

Had similar problems with my 04. If it was rear, I would say it is the e-brake. Front is a problem with the calipers. Mine were replaced under warranty due to the problem. They rub causing heat, which causes the vibration. Check to see if your truck had the TSB to replace the pads, rotors, and calipers. That is probably what will have to be done.

 

Brake Calipers....

Would that make enough vibration to make it seem like the front passenger wheel is hopping @ 60 mph?

It vibrates hard enough to bounce my windshield wipers off the windshield when it does happen, it just seems so random that it only happens maybe once every 6 months or so.

It happened once under load (towing about 5000lbs of wood pellets) but the other 3 times were empty.

 

If it is overheating the rotors, yes it will make it seem like the tire is square. Can't explain why, but since it happened to me, and I have heard of others with the same problem. In my case the rotors turned slightly blue from the heat. It may also have screwed up the tires I had on at the time, but they were almost shot anyway, so it wasn't a big deal.
I would definitely get the TSB done if it it already hasn't.

 

I have the same problem. It only happens once a while. The steering becomes completely loose which seems like its something in the front suspension. When I hit the brake however and check the mirror, the box bounces pretty bad too. I cannot figure this out. Other times the truck runs perfectly smooth.

If you search this and other forums it seems like a common problem without a clear answer. I'll probably start with the rotors, although I'm not convinced that would fix it since it's intermitted.

 

The emergency brakes on the rear is what cause this. There is a part called the expander cam that sticks. Here's a link to the fix...
https://www.f150online.com/forums/20...ke-repair.html

 

http://www.aboutautomobile.com/TSB/2007/Ford/F-1
Post 9

 

404 error.

 

I see it appended f-1 for some reason:

http://www.aboutautomobile.com/TSB/2007/Ford/F-150

 

I don't think so. Mine has done it infrequently for the last couple of years and I almost never set the emergency brake. I've driven it about 45-50 miles before it does it (always on the interstate when it does it between 65 and 70 MPH). If I keep going, it disappears just as mysteriously as it appeared.

 

If it feels like it's from the front and feels like the death wobble you may have some worn suspension parts. Check the control arm bushings, ball joints, tie rod ends, etc. You may have some play in one on those.

 

Mine is not a death wobble. It's more like broken belt in a tire. Mine has been doing it since about 18,000-20,000 miles (it now has only 27,000) and has been through 2 state inspections where the suspension is checked very closely by the inspector who is a friend of mine. If there was the slightest play, he would alert me. The way it mysteriously comes and goes is really strange.