I just recently purchased an 02 F150 SCrew. Ever since I got I've noticed that when I take off hard from stops something shifts in the back end. At least it feels like the back end. What it feels like is if I had something heavy in the bed and the it's being forced into the tailgate when I press the gas pedal. I don't know if it 's the diff. or the u-joints or something else in the drivetrain. Then I put a 7" Fabtech lift on it and I feel it even more now. Is this common on the F150's? Any ideas as to what it could be?

Thanks!

By the way, this place rocks!

 

This was a common complaint here for many many years until someone finally figured it out. In 99% of cases it is the slipyoke for the driveshaft going into the back of the tranny. It is made to do this so that it can have more leeway and not get in a bind. Some trucks have it louder than others, but it is not a problem that needs repairing. The lift probably made even more of a difference and the new angle is probably making it move more. Like I said, it ain't broke, so don't try to fix it. Many people have taken their trucks into ford to get this 'fixed' and Ford will fumble around underneath the truck, charge ya a couple hundred bucks and then a month later it will be back. Mine's been doing it since day 1, and it has never caused any problems. You might find someone who has a solution, but unless it really does drive you crazy, I would leave it alone. Most of the time, when people realize that it's not broken, they don't pay attention to it anymore.

HOWEVER, there are a few cases where there were/was:

-Loose U joints
-Loose spare tire underneath the truck
-Body lift bolts not tightened all the way (if you have a body lift)
And on trucks with monstorous tires::
-Axle wrap issue.

But like i said, chances are that yours is just doing what it's meant to do and I would try to ignore it.

Good luck and welcome to the site.