I have two 04 F-150 4x4s One is a Heritage 6cyl Manual that my son drives and the other is an 8cyl Auto that I drive. Both trucks have a little over 60,000 miles on them and they both have started to develop a bad vibration in the rear end intermittatlly. We found that to solve the problem when it happens, we can pull over and backup about 15-20 feet and it goes away. I seem to get the feeling reading this forum that there may be a defect in the original rear end components. Since it seems to be prevelant is this something Ford will fix out of warranty? Any suggestions?

 

there are several known issues: the parking brake seems to apply to your situation but Here is what I have found:

clutch pack in ls differential
parking brake dragging
pinion angle
drive shaft

of course there are also the standard tire and wheel balance.

do a forum search and there is lots of good data on what to do in each of these circumstances.

Good luck!

R

 

Im not sure of your setups, however rmccoll is correct. Aside from the obvious, like tire balance as mentioned, etc. The 2-piece driveshafts arent balanced well from the factory. My truck had a shimmy that I couldnt find, so I had the driveshaft completely redone & balanced with new u-joints. Now the drivetrain is whisper quiet & smooth.

 

with what you're describing, I'm 99% sure it's the rear parking brake hanging up.

take the wheel off and look at the e-brake pawl. spray it off really good with WD40 and get a good high temp silicone or other lubricant to help keep it from sticking

from what I understand though, the 04 heritage has the 97-03 drivetrain. it's kinda wierd it's showing the same as an 04+