rear diff noise?

[Gaki]

Noticed my rear diff makes a humming noise between 65-70mph, only under load, regardless of what gear that it is in.
Swapped out the diff fluid for redline (original looked like chocolate milk) and it's still making the same noise. If the diff was giving out, wouldn't it be making noise regardless of load or speed? Possible bad wheel bearing?
thanks!

[ChrisGS4]

How do the mounts look? If the rubber is not doing its job you could be noise being transmitted through the car that usually is muted by the rubber. Liqui Moly mos2 additive may quiet it down as a last resort.

[morris400]

either rear diff, bad bearing, driveshaft or driveshaft support. i have she same sound only mine is constant, im thinking wheel bearings. im having mine replaced in jan. if its not the bearings then i will try something else. but humming is generally a bad wheel bearing.

[2001S4OWNER]

I have had a few diff bearings go bad recently. The bearing in the front is pressed onto the shaft. It would be easier to remove the diff and inspect as you dissasemble. let me know i have a few diffs around that we could do an exchange program.

[Gaki]

thanks! I'll double check it here soon. I hope it's as easy as a wheel bearing.

[Scotty@Advanced]

Noisy wheel bearings pitch will change as a wheel is loaded or unloaded. Your rear diff is probably toast or at least a part of it is. Used diffs will be less expensive than repairing yours.

[Dimcorner]

Noticed my rear diff makes a humming noise between 65-70mph, only under load, regardless of what gear that it is in.
Swapped out the diff fluid for redline (original looked like chocolate milk) and it's still making the same noise. If the diff was giving out, wouldn't it be making noise regardless of load or speed? Possible bad wheel bearing?
thanks!

I was looking into this a few years ago and someone in AW replaced the bearing in the input shaft and it fixed it.