I have just purchased a used 2004 F150, 5.4Liter 4X4 with the towing package and 54,000 miles. I noticed once or twice when I start slowly from a complete stop, while turning left I hear what I would describe as a shutter. It sounds like its coming from the rear end. The vehicle does not appear to slip. It has only done it a couple of times and I can't seem to recreate it at will. I have a 60 day warrenty. Any ideas?

 

If it has a limited slip rear, add a bottle of friction modifier.

 

My '99 does the same thing.

 

i just took mine into the garage for the same thing, was told the rear clutch is shot and will cost almost 700 to replace. will adding friction modifier help now or no? I don't think they took it apart just elimanated all other sources!! I was told that pretty much the limited slip is engaged all the time for the most part creating that shutter...............can anyone chime in?

 

The noise is from the rear see it all the time try the modifer if it still bothers you replace the clutches it is common but no harm will come to the rear in fact it works better as far as traction is concerned.:santa:

 

right........will work good on snowy roads and people pay good money for diff locks!! I had the rear cover seal replaced not too long ago and the mechanic said they added friction modifier and would have noticed shavings in the fluid so its going back in for more diagnosing before I shell out that amount of money. I wouldn't worry about it other than its annoying!!

 

I just scheduled my '04 FX with the same "shudder" problem. It's been intermittent for a few months... when I turn right or left. Going to the dealer tomorrow. About a week left on my factory warranty, so timing is good.

More to come.

 

Update... Dealer claims that low tire pressure (-10lbs) on both tires on one side of the truck was causing the problem. I understand the physics - lower pressure would change the circumference and drag, messing with the gearing. Seems ok for the past week. If it does return, at least the problem has been logged with the dealer.

 

He's right!! Completely true and I'm surprised - that guy's good. Mine did that once right after getting new tires. New tires MAX pressure was 10 lds higher than the previous set. I pulled the shaft and Teflon greased the tail-shaft spline where the slip yoke slides on to.
It helped a little , but it still did it. It wasn't until I loosened the transmission support cross bar on the frame and transmission mount itself - then re-tightened everything did it quit.
If your pressures are up to par , I would give that a try.

NOTE: You have to support the motor under the pan when doing this. For perfect alignment, measure your shaft in between the frame rails in comparison to the center of the trans mount on top of the crossbar and tighten.

Also, your gear oil needs to be good - Free from breakdown and it MUST be by the book as far as modifier and 100% Synthetic.

 

I put that friction modifier in my 2003 F-150 and it still does it. Not sure what it is, but still has that shudder evertime i turn.

 

Had mine at the dealer last week to have the Friction Modifier added. My shudder has gotten better but it is not completly gone (270 miles so far).

With the Modifier now added, does anyone know if this will get better over time or is this as good as it gets.

Thanks!

 

I'm still noticing the same problem. But it's so slight that I'm wondering if I'm beinging paranoid. Happens when I turn a slight right or left, with medium acceleration. Just a quick shudder that nobody else in truck notices.

Is this shudder normal for posi ?

 

Also check your u-joints.

 

i had same problem after i replaced my 3.55s to 4.10s. It didnt do it until after I changed the diff fluid after 500 miles. Then it happened on every turn accelerating from a dead stop. The solution was to buy new clutches from Randy's Ring and Pinion (i got lucky as they have a shop in my town) and took them to the place that did my ring and pinion. They put the new ones in and havent had a single problem since. The stealer told me about 700 bucks and would lose my warrenty. I ended up paying 80 for the clutches and 200 for the install if I remember correctly. Hope this helps!!!!!

 

My '04 has shuttered from the beginning. Annoying but with 50K has not shown to be an issue.