I recently picked up an 04' F150 STX (owned two Toyota's previously) and am happy with the truck. Hell, I love it. But there's a slight recurring problem that I've noticed since a day or so after purchasing. When straightening out of turns and coasting at a low speed, there's a noticeable "whopping" noise. Noise goes away when breaking and accelerating (as far as I can tell over the noise of the engine). It is just most noticeable when (or rather in the latter part of a turn) and straightening out. Has new brakes and back rotors have been checked and fixed (they were in a little poor shape). Mechanics at Firestone said it could be something to do with the rear dif, but that their shop could not fix a problem there. So now I'm just checking for any other opinions. Could it be a rear dif bearing or a wheel bearing?

Greatly appreciate any help.

 

eat alot of beans?




but seriously, possibly the rear diff limited slip clutches. what is the axle code on the door jam sticker?

is it a 2004 heritage or new body style?

 

Haha...well I did eat at Taco Bell earlier today.

But axle code is B6 and it's a newer body style.

 

You have a limited slip diff. that is what the "B" is in the code.
Get your self some friction modifier and do some figure 8's then it should quiet down.

 

Yeah, knew it had a LS diff. I've got to head back into work right now, but will pick up some as soon as I'm out and will hopefully be back with good news to report. Thanks for the advice.