Ok I have a 2008 f-150 XLT supercrew with 4.6L. Over the last month or so I have been getting a bad vibration. It only happens once maybe every week or so when driving at highway speeds (Canadian 80 kph). When I pull over, put the truck in park and then drive again the vibration goes away. The u joint in the steering shaft went bad about a year ago and had to be replaced. I am hopeing this is not a transition problem. Any advice is greatly appreciated.
Thanks

 

http://www.ehow.com/about_6495843_ca...h-speeds_.html

 

I just bought a 2004 lariat and I was driving down the highway and I got a shake at about 45 mph and then did the same thing and stopped and it went away?? Took it back to previous owner and of course he drove it at that speed a couple of times and nothing happened. It's happened a couple of times since, he did change a valve in the vacuum system that has something to do with the 4 wheel drive and it didn't happen for a couple of weeks but then we have had it happen twice since then.

 

After some research I am pretty sure I have found the issue. My emergency brake is so corroded that is does not fully release. I have only had one side off but it took me about an hour of beating and messing around just to get the rotor off. I sprayed all the springs with oil but I think it is well past the point of salvation.

 

Can't see why a brake dragging would cause a vibration.

I did have a rented Bronco years ago that drove nicely but twice it developed a vibration that made me stop and look around underneath to see if the driveshaft was loose. Found nothing.

Start up again and drive away with no issues. It happened twice before I turned it back to the rental place. And I never found out what it was.