I have a 2006 Subaru Outback sedan w/ a 3.0R eng.  80,000 miles.

 

The drivers side front axle shaft had a ripped boot.

I replaced it with a aftermarket remanufactured shaft. The result was a loud whirring, humming noise that starts at 38 MPH and gets loud with increased speed.  No change D or N.

 

Tried another remanshaft, same results,

 

Re-installed original shaft the one with the ripped boot, same result.  I no longer suspect the axle shaft.

 

Checked the eng and trans mounts as best I could, they seem sound with no excessive movement.

 

Checked the wheel bearing, there is no movement, no play at all.  The tire rotates smoothly and quietly although a little hard, that is there feels like there is some resistance.

 

Replaced the axle shaft with a aftermarket NEW shaft.

 

My suspicion is that the wheel bearing is partially seized.  I suspect this because I had to hit the outer end of the original shaft pretty hard to drive in out of the bearing.  I hit it hard enough to deform the nut I had almost flush with the end of the shaft.

 

Any thoughts, suggestions?  Also does anyone know if a 2003 hub/knuckle will fit and function on a 2006?

 

Agreed on the wheel bearing.

Hitting things when bearings are going to take part of the impact is not good. Pressing is much less likely to damage the bearings.

Yep - sounds like bearings are hosed. 

 

2003 and 2006 knuckles are interchangeable physically but the ABS set up is different.

You could swap them and not have ABS. 

You could swap them and try to splice in the 2003 ABS sensor wiring (which the yard would typically gladly include for free) and hope the tone-ring counting fidelity is the same. 

 

2006 has bolt on bearings - just buy new bearings.  It's a really easy job - but if you're in the rust belt or unlucky they can be very hard to pull out. 

 

The bearings can generally take obsessive beatings, not that I recommend it of course, but at this point it doesn't much matter just gotta fix the issue at hand.   I've wailed axles so hard the end mushroomed and couldn't pull through the hub without cutting/grinding the ends off.  Bearings fine.   Again - not recommending it - i'm just saying you don't have to view the bearings as weak links ready to fail either. 

Thanks grossgary, I've had similar experiences, in fact this is the 1st time in 20 years of changing Subaru axles I winged a bearing, which is why I was a bit unsure if I was correct; seemed reasonable however.  I did have an Impreza axle shaft once that I beat into junk with a 16lb sledge hammer and never got the shaft out!  The end was mushroomed to almost 2" diameter! 

 

Didn't know the bearing is bolted on!  Thanks I wasn't going to check was just going to send it to the shop!  I'll check it out now, probably just do as you suggested buy one. 

 

This site is the best resource I've found for Subaru issues!  I don't always log on, mostly just need to do a little reading and I'm good!    Thanks all!

Another thing to watch for is loosening the nut with weight on the wheel, or tightening it by putting weight on the wheel to keep it from turning.

 

Any weight on it with the nut loose can put all the weight on just 1-2 balls in the bearing, pitting the ball and/or race.

 

Loosening with weight on is not an issue if you're replacing the bearing.

 

I use a scissor jack and a piece of wood to apply the brakes to keep it from turning (jack between brake pedal and seat, with another board keeping the seat from getting smushed).

 

Or get/make one of these:

https://www.amazon.com/Tool-Aid-66400-Steering-Depressor/dp/B0002UNRB2

copy -not that i'm encouraging pounding axles, just didn't want you freaked out about next time if it was a first time experience. 

 

yeah 2005+ are bolt on bearings and super easy to replace - if you don't have rust issues.  be prepared with air chisel, slide hammer or appropriate tools to slide the assembly out.  otherwise it's really easy and simple.  i flew to atlanta and helped a friend in his parking lot replace his with minimal tools and no work area. 

Little tip for when replacing hub assemblies without air tools or a lift. After you loosen the bolts for the hub (they shouldn't be very difficult) put them back in with a tiny bit of space between the head of the bolt and the back of the spindle. With a socket and an extension placed on the head of the bolt, you can give each one a few wacks with a hammer. Don't go nuts, you don't want to damage the threads, but sometimes that's all they need to push the assembly out. The bolts thread through, not into the knuckle and thread into the hub bearing assembly on the other side. If it's stubborn, you can beat on the edge of the hub itself and alternate. Don't need to remove anything other than the brake assembly and the axle nut. Everything else can stay in place.

How would an appropriate size gear puller work?  If it can grab the hub and use the axle shaft end to turn the puller shaft against; it seems like it would work, instead of pressing, pulling.  I'll find out this Sat anyway.  The hub is coming in this AM a little pricey but what isn't?

That could potentially pull the hub out of the bearing. Not a bad thing if it's a press it. Pointless since it's a bolt in. It would still be stuck on the knuckle if that happens. I also don't know if it would damage the diff and for that reason I never even attempt it. I beat it out like a savage.

This has been one giant Charlie Foxtrot!  It turns out that it's the rear wheel bearing!  I got caught up in a thought process that kept me going after the wrong thing.  I did at one point wonder if the noise was coming from the back but didn't actually sit n the back while someone else was driving.  After changing the front bearing without a change in the noise I sat in the back. the noise was clearly behind me and clearly a wheel bearing, right side it sounds like. 

 

The front bearing change went as to be expected.  Broke a caliper mount bolt and had to beat and heat the hub for an hour.  The shield got stuck on the hub but a little heat and the hub dropped right out.  The replacement went fine. 

 

This rear bearing will be the 1st I've done on a Subaru. It looks straight forward enough.  Any tips would be welcomed.