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Wheel bearing diagnosis help '08 Impreza


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While driving I can hear a hum coming from the front end.  Certainly sounds like a wheel bearing to me, but when I raise the front end and spin the wheels, they are smooth and quiet. 

The noise get louder with speed.  When I turn right the hum turns to more of a growl.  When I turn left, it almost goes away.  These bearings aren't cheap, so I would appreciate anyone's experience on this so that I don't replace the wrong bearing.

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While driving I can hear a hum coming from the front end.  Certainly sounds like a wheel bearing to me, but when I raise the front end and spin the wheels, they are smooth and quiet. 

The noise get louder with speed.  When I turn right the hum turns to more of a growl.  When I turn left, it almost goes away.  These bearings aren't cheap, so I would appreciate anyone's experience on this so that I don't replace the wrong bearing.

Turn to the right is loading the left bearing and accentuates the noise. Left bearing shot.  That's your diagnosis.

Just had my rear bearing 05 OB done yesterday. Not cheap but was directed by member GrossGary to Beck Arnley (Denso reman) which is much less than SOA. 

Some others suggest Timken brand works fine. Compare PartsGeek and Rock Auto pricing.

Peace of mind and quiet has returned.

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You might consider having both fronts done. I've replaced several on several Subes over the years, including my 08. It may be because of your road conditions, driving style, in my case I think it was a daily long sweeping curve on high speed entrance ramp. When the bearing overheats and distorts once, that's kind of the beginning. I went through a long diagnosis and eventually replaced the right twice and the left once.

 

I'm thinking now that National brand bearings maybe not so good.

 

I'ts very hard to localize which bearing is making the noise. The inboard and outboard on each side are separated by merely an inch or less .Right turn loads the outer left bearing , and the inner right as well. 

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08 probably has HBAs right? - easy to swap so, maybe do both sides as mentioned above?

 

did you try rocking/lifting the wheel in the 12 - 6 O'clock direction? I found a bad, noiseless, rear bearing like that once. The good side didn't move, the bad one moved maybe 2mm.

 

bad bearings can be hard to find.

Edited by 1 Lucky Texan
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Thanks everyone!  I figured it was the left one, but I have been wrong in the past about which side was the culprit when I had a rear bearing go on my Loyale.  There's certainly no play in any of the wheels when rocking the 12 & 6 o'clock positions.  And yes, '08 has HBA's.  Hardest part will likely be rusty bolts.  I had a rotor off the other day and that was a serious challenge that required some creative thinking and a lot of patience.

Edited by jetpilotdc10
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i wouldn't go on an 1,800 mile trip.

 

can you tell while driving if it's left or right?  if you think it's one side - it probably is.

 

have someone stand outside the vehicle and drive past them on both sides - which side is louder?

 

unfortunately there is no one test that will confirm every failing wheel bearing.  i have located a couple with the heat gun, but plenty also avoid determination that way too.

 

the old school "check for play" technique is nearly worthless with modern bearings.  the only one or two i've seen that would fail that test were so obviously wheel bearings that the test wasn't needed.

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Timken went on and is still working fine on my daughter's Impala, haven't done a soob so....?

 

pretty sure NTN is Japanese brand and may be an OEM supplier?

 

maybe a decent approach would be, IF you can be confident of which side is bad - spring for the NTN or OEM, but, if you feel you have to slap 2 bearings on, go with the Timken ?

Edited by 1 Lucky Texan
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Turn to the right is loading the left bearing and accentuates the noise. Left bearing shot. That's your diagnosis.

 

Not necessarily. With the bearing design on these cars you only load one half of the bearing (inner/outer) when turning. Turning left loads the inner half of the left bearing and the outer half of the right bearing. If the inner half of the right bearing is the bad half, the noise will subside, even though the right wheel is loaded.

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  • 2 weeks later...

Uh huh. Soak it with penetrating oil, and get a bigger hammer.

 

Does it have screws that thread in from the back side of the knuckle? Take one to the hardware store and match up the threads, buy two hex head bolts that are about an inch longer. Thread one in the top corner, one in the opposite bottom corner. Hit the heads of the new bolts with the hammer to help push the housing outward.

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Uh huh. Soak it with penetrating oil, and get a bigger hammer.

 

Does it have screws that thread in from the back side of the knuckle? Take one to the hardware store and match up the threads, buy two hex head bolts that are about an inch longer. Thread one in the top corner, one in the opposite bottom corner. Hit the heads of the new bolts with the hammer to help push the housing outward.

 

 

Sorry, sometimes I forget to mention things that I think are obvious (or assumed to be done) such as the fact that it's been soaking with PB Blaster for 24 hrs, and that I'm using a sledge hammer.  I tried threading longer bolts in from the rear, but without a hoist there's little room in there to hammer them.  The hub seems to have moved about .5 mm, but doesn't seem to want to go any further.

Edited by jetpilotdc10
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Well, If it wasn't bad before... Is it now!

 

Yeah I've had some hub assemblies just major stuck in the knuckle and the solution is almost always bigger hammer.

I had a Honda hub stuck so bad I had to remove the knuckle from the car, prop it up on wood blocks and wail on it with a 5lb sledge hammer. Still took a dozen solid hits to get it to start moving.

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