wheel bearings? or differential bearings? could be either one.

i'd be surprised if both wheel bearings are bad. but i guess it could happen.

 

So let us know where you think the noise is coming from w/ the stethescope.

If you still are not sure, I would drain the diff, unbolt/pull the axles completely out and see how the axle bearings feel when you rotate the hubs. Then unbolt the drive shaft from the companion flange of the diff and, with the axles still out, rotate the companion flange by hand. All of these should feel smooth, not notchy, when you rotate them.

Buckaroo

 

i'd probably look at replacing the wheel bearings either way you go. if you have the axles out, might as well replace them.

 

Well, I spent some time again trying to figure this out. It has to be either spider gears or carrier bearings. I watched a video on a ford rear end bad carrier bearing and the noise sounds just like what I'm hearing from mine. I think this is the howl at highway speeds and the vibration when slowing down. It seems to make sense that when I put pressure on the tire when spinning the wheel that the noise is louder. If the rear tires are off the ground and in gear (tires spinning), you can hardly hear anything. But I think once they are on the ground and the weight of the truck is on them you hear the noise.
Does any of this make sense to you?

 

yes it does

 

Have attached schematic of Rear Diff and another of Rear Axle for reference in case you don't have them.

In the diff, 4 bearings total - two side bearings and two on the pinion, front & back. Assuming by the carrier bearing, you mean the side bearings. I would think the load on the axle would be primarily supported by the axle bearings, not the diff side bearings.

When you were using the stethescope and couldn't get much noise out of the diff, did you run the speed up to 35-40mph? Both wheels turning? Contact point on the housing where the front bearing and the two side bearings are located?

Anyway, if you have ruled out the axle bearings, then you are into the diff and will need to tear down the diff assembly either way if it is the side bearings or the pinion bearings. You will know when you get in there.

I just did this - removed the carrier assembly myself, bought parts from Camelback Toyota and had a local guy that specializes in diffs rebuild it for me. Then I reinstalled the carrier assembly. Replaced all four bearings/races and other assorted disposable parts but my issue was definitely both of the pinion bearings. They sit up higher and, if fluid level gets a little low, they get starved for oil before the side bearings.

For my job, total parts for the diff were $230 with another $150 for the labor. I had the rebuild done rather than do it myself as I wanted to make sure that the diff was set-up correctly - it can be a bit touchy to get it right.

Buckaroo

 

I ruled out the pinion bearings because when I was spinning the wheels by hand, the trans was in neutral and the driveshaft wasn't turning.