Differential humming noise

[Alex_I]

Hi.

My Q70 has for the past 2 or so months began to make a humming noise (like the ones from failing wheel bearings) around the differential. According to my mechanic, where the drive shaft bolts into. Im not really sure how he can identify the noise origin so precisely though...

The thing is that last year I took it to Infiniti to change the drive shaft under recall. Could it be a faulty installation of the new driveshaft? The car has like 110k miles, all stock and driven like a grampa. Surely the differential cant fail so soon under these circumstances, right? Its also been serviced 2 times already. And Im driving the European diesel variant, with 170hp, so it doesnt even have to deal with that much power to begin with...

I have an appointment with infiniti in 10 days but I wanted to get some idea of what to expect before that.

Any ideas?

[VStar650CL]

Unless they changed the pinion seal or for some reason unbolted the companion flange during the recall, I doubt that could have caused a failure in the rear. However, since you can't put a stethoscope on a spinning shaft, noise in the rear U-joint can be impossible to discriminate from noise in the pinion bearing, It could be a defective shaft.