this is my 06 with a 5.4. its got the 9.75 axle with 3.73 gears. its got the single piece driveshaft. this whine your about to hear in the video started a couple months ago. since then i have replaced the wheel bearings and seals. and the diff fluid. and i did put in motorcrafts friction modifier. please watch the video and let me know if you know what the whine is.. oh and i know 100% its not the tires. and you can hear it over my exhaust even though in the video its hard too.and you cant hear the whine untill i get about 25 mph. thanks in advance for your greater knowledge

http://www.youtube.com/watch?v=YSk7z...ature=youtu.be

 

And I should also add there is no other noises or any strange vibrations or shutters

 

Sounds like the ring and pinion to me

 

If I had the truck, I could narrow it down, but not from here lol. 2wd or 4wd ?

Jack it up, try to locate were it's originating from. If it 4wd, - remove the rear shaft, run it 4wd, - is the noise still present ?

I mean , can't you narrow it down better than that? Well, - post all the needed info anyway, all that you can anyway. So no one else wastes their time asking for details.

 

Sorry. It is coming from the rear. I did try it jacked up. Nothing from the front end or transmission. And it sounds centered. It's not louder on one side or another. I thought pinion bearing? But not sure

 

And when I got up under there it was louder on the driveshaft side of the axle. And it gets louder with wheel speed not rpm. And it's constant

 

That sure is pointing toward the pinion bearing.

 

Pinion bearing...My rear was louder than my exhaust right before I swapped gears. I could tell you exactly how fast I was going purely based on rear end sound it was so bad and now its silent. Quiet to the point that I have to pay attention to my speedo now.

 

Ok but here's the deal, the back of the drive closest to the axle doesn't have any up and down or front to back movement like it usually does when that bearing goes bad? Does it have to have movement to be bad?

 

No mine didn't either and I checked 3 or 4 different times 'cause I was a little skeptical. After the gear install it was quiet again. Mechanic said the gears/bearing were starting to pit pretty bad along with my spiders. I told him to hang onto everything and show me and sure enough they were looking pretty rough. My $.02

 

Is the pinion bearing hard to change? I already know about the preload and everything.

 

Ok now when I'm at a dead stop and start to accelerate, I fill a flop in the rear end. So still pinion bearing??

 

Is the pinion seal leaking? When you replaced the axle bearings and seals were the axle seals leaking?

I had a pinion bearing go bad in a 74 Ford Stationwagon. I thought it was the tires at first. When I noticed that axle lube was on my right rear brakes and the pinion seal was leaking, that clued me in to what the problem was, a bad pinion bearing.

From the recording, I would guess it's the ring and pinion.

Or, it sounds somewhat like dragging brakes that don't have any pad left. You should have noticed that if you changed the axle bearings and seals though.

Noises are hard to diagnose in person sometimes, so good luck.

I listened again and I change my guess. I would guess pinion bearing or some other bearing in the diff.