i get a chatter in my rear end, only when accelerating from stand still and around a corner.. is this normal? truck does have posi and i have changed the fluid and added limited slip to it... should i worry?

 

Check u-joints. Also I'm a little confused, you have a posi and added a limited slip? I've always understood those to be the same thing. The stock LS does eventually wear out and cause problems similar to this.

 

I had to add almost two bottles of friction modifier to the rear end on my truck, sometimes one just doesn't cut it.

 

i added the limited slip fluid, whatever the proper name of the fluid is....
i bought the truck from the dealers auction.. it had that chatter since i bought it with 42000 kms.. so i changed the rear end fluid to see of it would help.. and it didnt.

 

Agree! Chatter in the rear end usually is a result of lack of friction modifier. For what its worth the last time I had my rear end lube changed the dealer told my mechanic that my VIN called for heavier gear oil than the 75w90 listed in the service manual, I believe it was 90w140. I asked him to call back and verify and they did. I belive the friction modifier used was Motorcraft and 3.5 ounces. If I were you I'd drop in another bottle of modifier.

 

I had this problem and I eventually took it in to have a fluid change. Not sure how much LS modifier they added to it, but I know that when I got it back they told me that although it might continue to chatter for a while, it would go away in a few weeks.

I drove it to Illinois to New Mexico after that which apparently wasn't enough. Once I drove it around town for a week or so after that, the chatter was gone, and has not come back.

 

sounds like torque convertor shutter. put some friction modifiyer in the tranny.