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BaconBait
02-23-2014, 10:30 AM
I spun out in the weather a couple weeks ago and went sideways into an embankment on the passenger side. I started getting a humming and very slight vibration coming from the rear. I had an alignment done and checked the tires without any change. Visual inspection showed nothing. Took the rear passenger side wheel off and turned the axle, nothing out of the ordinary was noticed. Made sharp turns left and right with no difference in sound/vibration.

Any thoughts or ideas on what it could be?

01 A4 1.8t QM

Update-
Took the brake off the passenger side rear and spun the hub. The bearing was destroyed. It was so bad that sharp turn to unload the weight of the car made no difference in the sound of the bearing. Spinning the hub with brakes and wheel on masked the fact that the bearing was toast.

BlackLock_A4
02-23-2014, 11:02 AM
Might have bent a control arm. They aren't very hard to bend with a small amount of force. They are made to be the weakest link so you don't mess anything up that is more important. It's weird that the alignment didn't show any damages though...

audiphila
02-23-2014, 02:06 PM
Could be wheel bearing?

frozenpuppy
02-23-2014, 02:51 PM
Could be wheel bearing?

Humming is a broad term. Is it a dull, rubbery kind of droning or a metallic, grinding kind of hum? That'll be the diff between a wheel bearing and a tire that's scrubbing out. I have a feeling you hurt your wheel bearing and bent your control arm with it a bit. If it was your tire, the alignment tech would have picked up on it I'm sure.

BaconBait
02-23-2014, 02:58 PM
The control arm would have been picked up in the alignment as well.

I ruled out the wheel bearing with the quick turns at speed to unload the wheel. I've had several bearings go out and this sounds very different.

It's more like a hum with a grind. I also has a slow pulse and changes pitch with speed. The vibration stays no matter if I'm turning or going straight.

I'll check the driveshaft bearing tomorrow just to rule it out.

frozenpuppy
02-23-2014, 03:11 PM
The control arm would have been picked up in the alignment as well.

I ruled out the wheel bearing with the quick turns at speed to unload the wheel. I've had several bearings go out and this sounds very different.

It's more like a hum with a grind. I also has a slow pulse and changes pitch with speed. The vibration stays no matter if I'm turning or going straight.

I'll check the driveshaft bearing tomorrow just to rule it out.

What about brake rotor? Maybe you bent your bracket or something? Brake rotors can make some ugly grinds too...

BaconBait
02-23-2014, 03:39 PM
Nothing abnormal when I spun the wheel.

frozenpuppy
02-23-2014, 10:21 PM
Nothing abnormal when I spun the wheel.
I think your right about the axle.. I think it calls for jacking all fours up and grabbing an auto stephoscope with the wheels spinning. If you do listen to the rear diff too. Maybe the curb pounded the axle into the diff and took out a bearing.

BaconBait
02-24-2014, 02:44 PM
Bearing is sounding most likely with the CV being next.

It's getting worse as well.

walky_talky20
02-24-2014, 03:09 PM
I'm thinking wheel bearing.

BaconBait
02-25-2014, 08:47 PM
I took the brake off and spun the hub by hand. It sounded and felt horrific. Just finished replacing it.

While I'm at it, the harbor freight and powerbuilt bearing pullers are crap. Due to the low grade bolt used in them I have stripped both of the 3/4" fine thread bolts.

Bordom
02-25-2014, 10:03 PM
How does it sound now?

BaconBait
02-26-2014, 06:44 AM
Normal.