Wheel bearing, Transmission, Differential noise

[howserss]

2002 Eddie Bower 4.0 100K miles . I just had my transmission rebuilt and the passenger rear wheel bearing replaced. Right after I had the wheel bearing replaced it started making a weird grinding noise between35-45 mph at about 1100 RPMs very light on the gas. It also does it very lightly at higher speed on the highway. I had the transmission done at a local shop at the bearing done at the Ford dealer. I took it back to Ford and they had it up on the lift and it does sound like the noise is coming from the tail of the transmission so they sent me back to the tranny shop. The tranny shop says it is coming from the rear end and traveling up the drive shaft. No one knows how to diagnose this. I feel it is the wheel bearing but its very hard to tell. Ford even swapped out the drive shaft and it did not make a difference in the noise.
Does anyone have any trouble shooting ideas?

 

[wbrudi28]

do you have the stock open differential? the ghetto way/easy way would be to do the BWM, then jack up the truck and put one side at a time, in the rear, on jack stands.

BWM engaged, with the unjacked tire on the ground, the open diff should only let that tire move. do one side, then the other. see if you notice a sound or a difference between the driver/passenger side.

hope you're willing to do it, they probably wouldnt do it at Ford though due to liability reasons.

 

[05XLimited]

Does the noise only happen when you are on the gas, or is it happening when you are coasting?

 

[howserss]

Only when lightly on the gas at about 1100-1300 RPM's. If on the gas harder the sound does not happen. If off the gas completely it is so light a sound most people cant hear it (but I still can).

 

[howserss]

do you have the stock open differential? the ghetto way/easy way would be to do the BWM, then jack up the truck and put one side at a time, in the rear, on jack stands.

BWM engaged, with the unjacked tire on the ground, the open diff should only let that tire move. do one side, then the other. see if you notice a sound or a difference between the driver/passenger side.

hope you're willing to do it, they probably wouldnt do it at Ford though due to liability reasons.

I'm not following anything you are referring to. What is BMW? What is an Open Differential? The entire vehicle is stock. I would love to try this but don't understand ho to do it. I do have 2 pairs of Jack stands and a nice 3 ton jack. Are you saying I could get only 1 tire to spin at a time with this method?

 

[Explorer0204]

http://auto.howstuffworks.com/differential2.htm

http://www.explorerforum.com/forums/showthread.php?t=149388

 

[05XLimited]

The biggest way to know its not the wheel bearing is that the noise does not change with RPM. It will change with speed. To me, it doesn't seem like the wheel bearings are bad.
The biggest thing is that if the Ford dealer is right and it is coming from the rear of the transmission, that it could have something to do with the output shaft.
If the tranny shop is correct, then the rear diff could be experiencing the whine that so many 3rd gen explorer owners have.
Another question that I have, has the rear diff fluid ever been changed?

 

[howserss]

The biggest way to know its not the wheel bearing is that the noise does not change with RPM. It will change with speed. To me, it doesn't seem like the wheel bearings are bad.
The biggest thing is that if the Ford dealer is right and it is coming from the rear of the transmission, that it could have something to do with the output shaft.
If the tranny shop is correct, then the rear diff could be experiencing the whine that so many 3rd gen explorer owners have.
Another question that I have, has the rear diff fluid ever been changed?

I also had the ring and pinion gear replaced and it did not alter the grinding sound. A few years ago I had the clutch packs replaced in the rear end. The rear end has always made the humming sound above 50 or so but that is gone now. Just replaced by the horrible grinding sound. The grinding started the day I got the new wheel bearing. When under the car it does sound like it comes out of the rear of the tranny. I drove the car for about 1.5 months with the new tranny and it never made the noise then the day I get the bearing it starts making the noise. I think its too big of a coincidence. I might try to make a video of the sound.