All,
Just an update. The TSB for the 2004 - 2005 models was done to my 2006 and the tech went both ways with the wedges and finally just put it back to bone stock. Nothing worked. As before, so far the drive shaft replaced, clutch pack in rearend replaced and pinion angle a NO-GO. I'm now within 300 miles of my warranty being out and am on the short list for the Ford engineer to look at it. Again, when it's fixed, I'll drop a line!

 

I also get vibration but only at take off from a dead stop
It's like I'm getting out of a hole, the truck strugles for a second or two and then it's on it's way very wierd feeling.
My gues was the tourque converter or the LSD (Any idea?)
I got this truck two weeks ago so it's still fairly new to me 2004 fx4 with 3.73 lsd
Didint try towing with it yet.

 

Latest update on the Ford Engineer(so called expert). Guy came up from FL to South GA to look at my truck w/trailer hooked up. Went through all the capabilities and weights and said that because my truck had the 3.55 rear and 18 in wheels, my actual towing capability was 8100, not the advertised 9500#. Also, he did some hocus pocus math and came up with a pin weight of 1819# in the bed which is 800# over trailer manufacturer pin weight of 1068#. Trailer was empty and very little gas in bottles. Bottom line with the engineer was I was experiencing "axle wrap". On acceleration, the torque was so much with the weight that the differential went up and the right leaf started warping. He promised faithfully that if I changed out the springs or put a helper on it, it would stop...he didn't say anything about the 5K airsuspension on the truck! He did say that given the weights, my truck was overloaded for the trailer. So, wife and I went to local trailer place to look at trading back to a bumper pull. The one we decided on was a 6700# trailer fully loaded. I asked the salesman if I could hook it up and pull it before closing the deal and we did. Before we could get out of the lot, vibration started all over again!! So, it ain't the axle wrap, I figure it's the transmission or torque converter. Sorry for the long post, but promised an update. More to follow...I'm sure!

 

Did you guys ever find out whats going on with your vibration? We have a '05 F150 with 24k mi that is having VERY similar problems.

Symptoms timeline:

The rear pops when you turn tight in a parking lot.

The tranny fluid was low and we could not find where it was going. Put several qts in it and finally took it to the dealer where they replaced the bad seal between the transmission and transfer case.

We have a vibration from about 40mph-55mph under medium-full throttle. A lot worse when towing. Put it in neutral and it goes away. Rev the motor and you don't feel it. Only happens under load. Happens in 3 and 4th gear. Goes away once the torque converter locks up.

 

I get a slight vibration when I tow my motorcycle trailer (7X14). The first few times it didn't do it, but after the receiver got 'worn' in it got worse. I haven't figured out exactly how to fix it..

 

Last Update on the Vibration Issue. I think it must be an inherent problem with the F-150. I also think Ford has over-rated the towing capability of this truck. I took mine for the last time to the engineer and then we hooked up an exact model of mine to it (an '08 model) and it even vibrated. Since the previous post, I went back to a bumper pull trailer, 6700# with a tongue wt of 870. The truck still vibrates starting off, but not as bad, but still does it. My '02 Suburban (wife's car) acts like there's nothing there. So, I still love my truck and will keep it, but I ain't satisfied with the vibration. I still think it's the transmission, but can't afford $4K to "fix" it! I'll keep watching the posts. Hope someone here finds out what's wrong! :-) Ed

 

Try having the dealer perform the electronic Auto Tranny service ($171). I had very bad shudders and vibrations in my '05 SCrew Lariat and they are now 100% cured. The problem is rooted in the torque convertor. I am posting this in several places but I believe it to be the answer for several issues.

 

This vibration issue does sound like it could very well be the torque converter. However, if the pinion angles on a two piece driveshaft changes enough while under a medium to heavy load to cause a vibration, about the only way to correct this situation would be to add small counterweights to the driveshaft itself and see if this makes the vibration go away while towing a trailer. I don't think adding weights to the driveshaft itself would hurt the clutch pack any. Just an idea. Jim