A buddy of mine said I need to go to the auto store and buy some stuff to put in the rear end .. He said its a little bottle of stuff and that it stinks real bad.. Just a ? do I need to buy a bottle for the front diff as well ?? The truck only makes the noise when I turn and take off from a dead stop..

 

If you are referring to limited slip friction modifier, it only goes in the rear, and you should buy it from the Ford dealer.

If it is limited slip clutch chatter, it may be best to change the fluid in the rear - it takes 75W140 full synthetic and friction modifier. What year and model is your truck, and how many miles does it have on it? Does it in fact have limited slip?

 

It is a 2003 FX4 with The 5.4L ( Its a crew Cab ) It has 164000 Miles on it.. about 3 months ago it appeared the seal was leaking because there was always a wet spot on the diff housing , but I had it checked and they said the level was fine.. I will call ford about the friction modifier , thanks for the help.. I may look into another rear end as I have access to a shop.. But if the modifier stuff will fix this then who knows.. the sound is alot worse when I pull my 12ft trailer ( roughly 3000lbs with steam cleaner and all )

 

What kind of sound is it? My truck makes a clunking noise when I take off from a start.

 

If you have limited slip and 164k on it - and the rear fluid has never been changed, it's overdue. Recommended change interval is 100k.

Do you have limited slip? Post the axle code from the door jamb sticker.

 

I think the code for LS is H9, but the OP said sound. Like 73mav posted "what sound" I was under the impression the chatter doesn't make any sounds to speak of. It happens when turning and you feel it over hearing it. Feels like a chatter? Idunno, maybe it's noisy when they get real bad.

I guess the OP should post WHAT sounds or maybe it's a clunk? If it's a binding sound?

Sounds like ? You getting any vibration @ 45-65 mph? More info.

 

Wel I drained and put new fluid and put the friction modifier in there and ,that was it .. I have tried it for about 3 or 4 hours today stoping and starting while turning and no sound or vibration... Now this leads me to wonder wether the trans fluid has been changed .. It does not appear or smell burnt , but I guess thats a project for another day .. thanks for the help >>>>

 

The sound it was originally making must be a secret , axle code as well...

Crap, there I go , talking to myself again