Last month I bought an 04 f150 and its been great. The only problems i have had so far is the window motor broke. The other, i dont know if it is really a problem. When I am stopped and turn the wheel pretty hard then give it some gas i get a vibration that feels as if it is coming from the rear axle. I have a 3.73 Limited Slip axle (code B6) and could it be that the clutch in the LS axle is shot? if so how much would this cost to repair and is it necessary to repair immediately?

thanks

 

Change the diff lube with 75W140 synthetic and a bottle of Ford friction modifier.

 

In the owners manual it says that under normal driving conditions the rear LS diff will exhibit a slight vibration and noise when turning sharply at low speeds, this is normal and just shows the diff is working properly. Quote from manual. Mine has been doing it with not ill effect since buying it a month ago.

Regards,
Pete

 

If it has close to 100k on it, the diff fluid needs to be changed.

 

I changed mine and it made no difference at all and it had the modifier done, it seems to be normal, I drove another LS equipped 150 and it did it even more tech said it was normal.

 

The truck has 97k miles on it but the guy i bought it from had just gotten the rear end rebuilt because there was a bad bearing in it. He said that since he had to pay for the labor to take everything out it was economical to have the whole thing rebuilt while in there. So the fluid has been changed

 

Did he use 75W140 synthetic and Ford modifier?

 

i have no clue. All i know is that he took it in to a shop and they rebuilt the thing and replaced the bearing