SOLVED: Bad wheel bearing or..?

[vegashelipilot]

So my father's '90 325i recently started making a humming/droning noise, almost like tire hum but much louder, above 40 mph. We replaced all the wheel bearings with Febi Bilstein brand last year, about the same time we bought new tires. The sound is entirely dependent on how fast the car is rolling (if you throw the car in neutral and coast there is no change in pitch or loudness), which leads me to believe its not a driveshaft issue. Could it be the CV axles? Or just a bum wheel bearing? Anything else I'm missing?

Edit 1/25/20: It was a bad wheel bearing after all. For anyone about to replace their wheel bearings maybe avoid Febi Bilstein, these were barely a year old. (I replaced the wheel bearings with FAG brand on my E30 about the same time and have not had any problems).

[Sunnyledge]

Driveshaft or rear CV shaft?

[zwill23]

Bad wheel bearings will typically get louder while corning, have you noticed anything like that? It's possible that it might be time for a brake rebuild, a sticky brake piston can cause the brake pad to ride on the rotor a bit sounding like a freight train as you head down the road.

[vegashelipilot]

Bad wheel bearings will typically get louder while corning, have you noticed anything like that? It's possible that it might be time for a brake rebuild, a sticky brake piston can cause the brake pad to ride on the rotor a bit sounding like a freight train as you head down the road.

I don't notice any change in the noise while cornering (I specifically tested for this by swerving the car left and right). The brake pads and rotors were changed when the tires and wheel bearings where changed, but the calipers were not rebuilt.

[zwill23]

Rebuilding the calipers or at least doing a brake fluid flush might be worthwhile. Otherwise, I would inspect the CV axle boots and make sure they're not torn.

Edit: A dragging ebrake could also have symptoms like you described.

[noid]

To check if the wheel bearings are bad: raise the car, and grab the spring, when you spin the wheel by hand you will be able to feel even the slightest grittiness through the spring. If it feels smooth, its fine.

[TobyB]

Can't believe no- one's mentioned the driveshaft center support bearing yet, nor the driveshaft splines...
....or u- joints.

you often have to pull the driveshaft to feel stuck u- joints.

t

[vegashelipilot]

Just wanted to update that it did end up being a bad wheel bearing (the right front). Replaced it with an SKF this time. For anyone about to replace their wheel bearings maybe avoid Febi Bilstein, that bearing was barely a year old.