I have two Legacy's with 4EAT and AWD: a 92 (270k) and a 93 (183k)

 

In both cars there is a similar humming noise at 55-65.

 

I have determined is not the wheel bearing (92 bearing was bad, but changed the bearing and no change in the noise) or tires (several different sets tried between the two cars) . It is also not brake noise.

 

Cornering, acceleration, and deceleration has no effect on the noise at all...I can put it in neutral and take a curve at 60mph and the noise stays the same

 

Since this is a constant noise, could this be a symptom of bad DOJ's?

Related question: My 93 also vibrates on acceleration around 20mph, but not as bad when cold.

My guess is a worn transmission mount at least partially causing this, and cold weather makes the rubber in the mount stiffen up?? Possibly with bad DOJ adding to the problem...would this make sense or am I off base?

Note: I posted a similar question several months ago but did not have the 93, and since I have more info I didn't want to drag up an old post

are they subaru axles or aftermarket? as you saw i think in that other thread there are certainly many options. i'd suspect axles first, but you'd really be throwing parts at it to verify.

Not sure, i have never replaced them. Is there a stamping or anything on them that would indicate whether they were genuine Subaru or not?

 

I am hoping to narrow it down to the most likely cause...throwing parts at it is what I am trying to avoid as much as possible since the $$ and time are issues, so I definitely appreciate your suggestions