o/k, I have an 04 FX4 about 65,000 miles. 5 year or 75k warranty expires July 30 of this year. fairly recently now when I take off from a stop, especially turning, the rear tires almost shuter, and the truck shakes but once I get going all is well. Everything on the truck is stock, only thing new are brakes and Toyo Tires installed Saturday,

1) is this a rear diff issue, or maybe the clutch packs from what I've read?
2) would this be covered under warranty, and if not, how much to fix?

I love my truck but this performance is unacceptable. Other than that truck has been great.

 

It sounds like it could be in the diff. It should be covered under your powertrain warranty. Is it a Ford ESP?

 

My '05 had the rear rebuilt at the Ford dealer last year under warranty. It hummed and vibrated. I would get it looked at. My truck had a tsb for this problem that the dealer confirmed. Maybe look it up here and see if your '04 may have one too. No matter what, take it in and get it looked at.

 

Certainly sounds like a clutch pack issue. I went through it a few months back. There is a TSB (for limited slip diffs.) on this problem. Note: The part # for the clutch pack does not change. However the recommended fluid does change.

 

Here is your TSB INFO:
TSB # 06-4-4
• LIMITED SLIP AXLE CHATTER, SHUDDER, BINDING SENSATION, OR VIBRATION DURING LOW SPEED TURNING MANEUVERS
https://www.ford-trucks.com/tsb/full...php?tsb=06-4-4

 

Thanks everyone:

Had a Ford Tech drive it during lunch today, confirmed clutch packs on rear differential are shot. 100% covered on my 5year/75k mile warranty. Tech said the bill would be about $800 if I had to pay for it myself. Truck goes in the shop in the morning.

 

That's good news. I'm glad all is ending well.

 

My "new to me" '04 FX4 SCAB is exhibiting the same problem. It's out of warranty. Would the TSB still cover me even though it's out of warranty?

 

My 05 is doing the same thing. Plus no warranty

 

Most likely not. But you can ask your local dealer. They have the authority to do the repair under warranty under certain conditions. But if you have a lot of miles over the warranty limit they most likely will not repair the clutch packs under warranty.

 

I have the same problem on my 04 supercab 4x4. It is an XLT 5.4 with the 3.73 LS in the rear a no warranty. I've heard swapping out the clutch packs is not to bad of a job. My big queston is Will that fix the problem, or does it come back again? Ford wants like $750 to do it, I think we can do it in the gargage for like $150 (parts). I've also had a couple of 4x4 shops quote $1000 to put in the Auburn LS. I wouldn't try swapping carriers at home. So what is the thing to do here, new clutch packs or new LS?

 

If you are planning on doing the clutch packs at home, you can do a new limited slip carrier as well. You will be just as deep into it either way.