2003 F150 FX4 4.6 80K
It seems like when I accelerate away from a stop turning either direction than something is slipping or not quite smooth. It does not do it accelerating in a straight line. Diff and trans oil have about 10K on them.

Could the factory limited slip not be functioning correctly?

If I decide to replace the diff with a Tru-Trac LS. Will I be able to get a good gear pattern using just the side shims, re-using the original gear set and not removing the pinion?

I don't want to use a locker because this is my DD and it has to tow a 5000# camper. Lockers were not recommended by the diff suppliers for towing.

Thanks, Dan

Maybe it is the one legged wonder working to its full advantage.

My brothers 04' F150 did that. Felt odd enough that he traded his truck in. My buddy bought the same year truck about 5 months later and it does the same fawking thing. Cant really pinpoint it...like a hesitation. We drained the fluid in my brothers trucks rearend and everything looked good. He went as far as to flush the tranny cause he thought that might be it. Guess its a Ford thing...

was the friction modifier added to the rear diff when the fluid was changed ?



and you can get a mini install kit, it comes with just the shims

I used Mobil 1 synthetic gear oil, which says it does not need friction modifier.
That being said, it made noises and squeaks. So I put in the friction modifier the next day and the noises went away. I drove it about 50 miles with out the modifier.
Dan

the chatter will be there if there is no modifier on a clutch style LS



did you use a ford modifier ? or some elcheapo ? some cheap additives can make it worse

and the true trac is a nice unit for a DD. someday ill get one for my f250 as rebuilding and shimming mine sucks for 10k of use :shaking:

could be the shitty ford trac lock. i have had two of them break on me. the clutch packs rub on the housing then they end up burrowing thru it and the clutches have enough room to move around break. or they split the casing in half. pretty sweet design huh!!?? who knows it could be sumthing else. thats just my 0.02 worth