Outer Limits 4x4 Board

My lil 4runner has a very annoying whine in the diff. It only comes audible at about 90kp/h +. The diff itself has very minimal backlash and appears to be in good nick.
As soon as I take the pressure off the diff (back off or put clutch in) it goes away.

Could this be a bearing prob? or does it sound more like a centre prob?

Sounds like the pinion bearings allowing some movement of the pinion forward and back, thus running on lapped surface, then on unlapped surface.

Have you removed the tail shaft on the diff pinion, and checked the pinion nut for security??

That would be the first thing I would check.
It was a common problem for a while with the borg warner diffs in comms and falcs a while back.

I assume its got the correct oil level, and the oil is changed as required.

You havent mentioned any vibration, but a check of the unis would be a good idea as well.

Let us know how you get on.

Trains

ive got the same problem in my 4runner. I changed the front seal in the diff and it stopped the while for about a day then it came back as loud as ever. Im guessing everything settled back to where it was hence it whining again. sorry forgot to mention i dont ahve any vibration either