my 04 f150 xlt vibrates in the rear end only when i corner on dry pavement. anyone have any ideas. I have had many guys tell me that the ford trucks are horrible for rear end problems......anyone have similar problems?

 

I have the same exact vehicle with the same exact problem. I'm not sure of the exact fix yet but if I were to guess I would say that the differential isn't slipping on those tight turns and just needs to be rebuilt. Somebody suggested to me that just changing the differential fluid might fix it.

 

Do you have posi-trac rear diff in your truck? if you do, then you need to change the diff fluid and add a posi-trac additive to correct the shudder when turning.

 

I'm taking my 04 4x4 to my dealer this week. They told me that it's the clutch packs in the rear end doing that. Mine does that same thing in slow turns and leaving a stop light. If so many ford trucks have this problem, why doesn't ford dosomething about it ?

 

That's why they specify synthetic gear lube and friction modifier additive. It's not just Ford, this is common with any factory limited slip differential that uses clutch packs.

 

its a normal thing for fluids to need to be replaced, ford has done nothing wrong here

 

if you have LS axle it would be your clutch packs. there is a TSB out on this

 

Like what has been said, It is the clutch's in the rear end.

 

Makes me kinda wonder if the dealer used the friction modifier or not. I've got 106k on it but I had it changed at the dealer at 90k. I bought the truck used and it had 70k when I bought it. No problems up until now, maybe it wasn't changed properly before I bought it . I would guess that the fluid at the dealer has the modifier in it already though.

 

I also have the same problem with the shutter on turns. I am not familiar with clutch packs. Is it something that is deteriorating as in metal parts floating around in the rear end, eventually causing the whole rear end to be rebuilt. In other words if nothing was done about it will create a bigger problem?

Thank for anyones help

 

It's normal if you have LS. The sharper turn you make, the more you feel it. Just means the outer wheel is having to turn faster than the inside wheel and it is trying to do it's limited slip.

 

Put in some good synthetic like Amsoil or Royal Purple.

 

My sticker on door say for axle H9 so from some of the previous post I must have a LS Diff. Thanks for the quick reply I'll try the additive and some good synthetic oil. I just was not sure if ignoring it would create a bigger problem.

 

Anything ignored don't go away and don't turn up the radio if it gets louder.

 

You might want to try some dino oil in the rear.I say that based on my experiance w/ my l/s. I have an eaton aftermarket l/s and the manufacturer recommends"Eaton Posi units perform best when using GL4 (or better) mineral/petroleum based gear oil. A four ounce bottle of friction additive/modifier is also necessary for optimum performance.".
One day before a 4 hour trip to orlando,I swapped out the dino oil and used a synthetic.For the first time ever,I got the nasty chatter when making very sharp slow turns.When I got back home I replaced it w/ what is recommended and it disappeared.I still dont understand why but it made a difference.
It could make a difference for you as long as the clutch packs are in good condition.

fyi