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2012 Subaru Impreza Ft wh Bearing/Steering Knuckle #3854109
09/14/15 07:13 PM
09/14/15 07:13 PM
Joined: Dec 2011
Posts: 266
Northern NJ
deanm11 Offline OP
deanm11  Offline OP
Joined: Dec 2011
Posts: 266
Northern NJ
Original owner on a hatch (2.0 naturally aspirated) approaching 70k miles. Right front wheel bearing getting noisy after a couple thousand miles on a highway trip over a few days.

I believe the hub assembly, with pressed in sealed bearings, presses into the knuckle. New aftermarket hub assemblies are ~$50 but would require removal of my knuckle and having pressed in. I found a 7000 mile 2013 impreza complete knuckle/hub assembly for $50 shipped to me! Comes tomorrow.

Took off the front wheel tonight for a peek at the axle nut and knuckle attachment points. As to the latter, ball joint at bottom and tie rod, two bolts to strut. I'll mark the strut and can disconnect the ball joints.

Anyone have insight into the axle nut. Believe torque spec is 140ft-lbs. There is some kind of internal tin that is staked to a groove in the axle. I'll unbend that and hope simply undo the nut. My 1 1/4" socket fits perfectly. The axle should come right out the back ? Just torque back up and stake to the groove? No bearing "set up" like older setups ? Any tips appreciated.

[img]http://s234.photobucket.com/user/deanm11/media/002_2.jpg.html[/img]

[img]http://s234.photobucket.com/user/deanm11/media/003_2.jpg.html[/img]

Last edited by deanm11; 09/14/15 07:14 PM.

2012 Subie Impr 2.0 99k M1EP 0w20 7.5k
2002 Tahoe 5.3 153k 5w30 syn 7.5k
Re: 2012 Subaru Impreza Ft wh Bearing/Steering Knuckle [Re: deanm11] #3854156
09/14/15 07:56 PM
09/14/15 07:56 PM
Joined: May 2004
Posts: 2,494
Northeast
sxg6 Offline
sxg6  Offline
Joined: May 2004
Posts: 2,494
Northeast
I have a 2009 legacy, and replaced one of the front wheel bearings/hubs late last year.

On my car, there are 4 bolts that hold the wheel bearing/hub to the knuckle, it doesn't need to be pressed in. It can be difficult to remove the wheel hub and brake dust shield from the knuckle if rust is present, but the wheel hub should just slip into place once everything is cleaned up.

It's good that you found a knuckle with an oem hub, some subaru owners report cruise control issues with cheap aftermarket hubs. My guess is that the cheap aftermarket wheel hubs use less, or lower quality magnetic materials, and the wheel speed sensor doesn't get a good reading on them.

On 2005-2009 legacies, it is very common for the "pinch bolt" above the ball joint to break when trying to remove it, outlined in red below.



Since you have a whole new knuckle, breaking that bolt is less of a concern. It wouldn't be a bad idea to have a new bolt on hand though if the new knuckle doesn't come with one. That bolt is a funny length, but you might still be able to find one locally if needed.

You could also remove the castle nut and cotter pin on the bottom to remove the knuckle, but then you'd still have to wrestle with the pinch bolt to get the ball joint out, or just buy a new ball joint too.

As far as the axle nut goes, I just took the nut right off and didn't bother trying to unstake it. Though with that said, I was also replacing the whole axle, and had a new axle nut ready to go. You could try to unstake the nut, it might just be less off a hassle to buy a new axle nut, I forget how much they cost though. The wheel bearing should hopefully slide right off the axle from what I remember, I don't think mine put up much of a fight.

It might be tempting to tighten the axle nut down when the car is on the ground to make things easier, but you should do it with no weight on the hub to avoid damaging the wheel bearing, just have a buddy hold the brake pedal down.

Same idea (no weight on bearing) goes for loosening/removing the axle nut, but this is not a concern for you since you're replacing the wheel bearing/hub.

*After looking at that picture above for a second time, I would definitely plan on that pinch bolt I outlined breaking. When I went to remove that bolt on one side, I went right in without the knowledge that it is prone to breaking, and broke it right off the bat.

The second time around on the other side of the car, I hit that bolt with pb blaster for a week straight, and it still broke when I removed it. I've never used heat before to help remove a rusted bolt, so maybe that is how a technician would remove that bolt without breaking it.

Last edited by sxg6; 09/14/15 08:02 PM. Reason: Added extra info after the *
Re: 2012 Subaru Impreza Ft wh Bearing/Steering Knuckle [Re: deanm11] #3854162
09/14/15 08:00 PM
09/14/15 08:00 PM
Joined: May 2015
Posts: 139
Austria
LubeLuke Offline
LubeLuke  Offline
Joined: May 2015
Posts: 139
Austria
The bearing is a unit bearing design. It contains the hub and bearing. The unit (or hub) bearing bolts into the upright without the need for a press. A rubber mallet is sometimes needed.
It would be easier to replace the unit bearing rather than the whole knuckle, as replacing the knuckle will require you to have a wheel alignment afterwards.

The axle nut must be torqued correctly to ensure proper preload of the wheel bearing.

Re: 2012 Subaru Impreza Ft wh Bearing/Steering Knuckle [Re: deanm11] #3854180
09/14/15 08:14 PM
09/14/15 08:14 PM
Joined: Dec 2011
Posts: 266
Northern NJ
deanm11 Offline OP
deanm11  Offline OP
Joined: Dec 2011
Posts: 266
Northern NJ
Thanks for the tips guys. Sounds like I should just unbolt the axle and try to R&R the hub assembly without disturbing anything else at all. I guess as long as the axle drops out of the way and I can get at the 4 bolts, It'll work.


2012 Subie Impr 2.0 99k M1EP 0w20 7.5k
2002 Tahoe 5.3 153k 5w30 syn 7.5k
Re: 2012 Subaru Impreza Ft wh Bearing/Steering Knuckle [Re: deanm11] #3854184
09/14/15 08:18 PM
09/14/15 08:18 PM
Joined: May 2004
Posts: 2,494
Northeast
sxg6 Offline
sxg6  Offline
Joined: May 2004
Posts: 2,494
Northeast
You know, I don't know why I didn't think of that, that's a good idea. Access to the bolts is a little tight from what I remember, but I think it's doable.

*I think I remember moving the steering wheel to the left and the right made it easier to access some of the bolts that were a little tougher to get to.

Re: 2012 Subaru Impreza Ft wh Bearing/Steering Knuckle [Re: deanm11] #3854189
09/14/15 08:24 PM
09/14/15 08:24 PM
Joined: May 2015
Posts: 139
Austria
LubeLuke Offline
LubeLuke  Offline
Joined: May 2015
Posts: 139
Austria
The drive axle will not drop out of the way with the unit bearing and upright still in place. You can access the unit bearing bolts with a socket extension and ratchet. You may have more clearance if you turn the wheel one way or the other.

Re: 2012 Subaru Impreza Ft wh Bearing/Steering Knuckle [Re: deanm11] #3854190
09/14/15 08:25 PM
09/14/15 08:25 PM
Joined: Dec 2011
Posts: 266
Northern NJ
deanm11 Offline OP
deanm11  Offline OP
Joined: Dec 2011
Posts: 266
Northern NJ

First, I will make sure the donor hub comes out of its knuckle nice and easy !


2012 Subie Impr 2.0 99k M1EP 0w20 7.5k
2002 Tahoe 5.3 153k 5w30 syn 7.5k
Re: 2012 Subaru Impreza Ft wh Bearing/Steering Knuckle [Re: deanm11] #3854193
09/14/15 08:27 PM
09/14/15 08:27 PM
Joined: Dec 2011
Posts: 266
Northern NJ
deanm11 Offline OP
deanm11  Offline OP
Joined: Dec 2011
Posts: 266
Northern NJ
So maybe have to disconnect the strut/upright side only... allow enough room to push the knuckle to outside away from the axle and loose hub?
.... I'll try once the hub is loose without disconnecting the upgright first.

Last edited by deanm11; 09/14/15 08:28 PM.

2012 Subie Impr 2.0 99k M1EP 0w20 7.5k
2002 Tahoe 5.3 153k 5w30 syn 7.5k
Re: 2012 Subaru Impreza Ft wh Bearing/Steering Knuckle [Re: deanm11] #3854213
09/14/15 08:48 PM
09/14/15 08:48 PM
Joined: May 2015
Posts: 139
Austria
LubeLuke Offline
LubeLuke  Offline
Joined: May 2015
Posts: 139
Austria
Yes on the front you can unbolt the strut to allow the axle to slide out of the unit bearing. But the strut has a camber bolt. Unbolting the strut will require the camber to be reset when you bolt it back on.

Re: 2012 Subaru Impreza Ft wh Bearing/Steering Knuckle [Re: LubeLuke] #3854229
09/14/15 09:08 PM
09/14/15 09:08 PM
Joined: May 2004
Posts: 2,494
Northeast
sxg6 Offline
sxg6  Offline
Joined: May 2004
Posts: 2,494
Northeast
A couple more quick tips after looking at one of my old knuckles..

From what I remember, the wheel bearing/hub and brake shield were most rusted in place in the round center part of the knuckle, as shown in the pictures below.

It looks like the hole that the wheel speed sensor goes into would be a good place to spray some pb blaster or something similar into, to help free things up. Also maybe spray a little bit from behind the knuckle, around the the area where the 4 bolts are, where the cv axle goes into the bearing.

I think the first time I went to replace one of my axles, I first tried to remove the axle from the hub with the strut disconnected, and it was a very tight fit. I didn't know how much you could safely flex the axle joints, so I gave up and ended up disconnecting the lower control arm instead. I'm pretty sure some other legacy owners have said what luke said, that you should be able to get the axle out by just disconnecting the strut from the knuckle. It was too close for comfort for me, but it's worth a shot since that would be the easiest route.


Re: 2012 Subaru Impreza Ft wh Bearing/Steering Knuckle [Re: deanm11] #3868827
09/28/15 08:10 PM
09/28/15 08:10 PM
Joined: Dec 2011
Posts: 266
Northern NJ
deanm11 Offline OP
deanm11  Offline OP
Joined: Dec 2011
Posts: 266
Northern NJ

Thanks again for your tips. Sorry for the delay in updating. I did the job without much difficulty- the most difficult being losing one of the nuts for the bolts that attach the knuckle to the strut.

I got a ball joint on my complete knuckle and it felt good, so I determined it may actually be easiest to just swap the entire knuckle. I was going to have to detach from the strut anyway, and I figured disconnecting the tie rod and ball joint was less hassle than R&Ring the hub assembly in tight quarters. Pretty sure it was the right call. The tie rod and ball joint responded just fine to the hammer on the side of the knuckle detachment method.

I went out and bought a new strut nut after not being able to find it. Went for a test drive when done and there was a tinny rattle sound on any bumps- sounded like the dust shield. It was the missing nut sitting on top of the knuckle, in contact with the dust shield!

Thanks again.


2012 Subie Impr 2.0 99k M1EP 0w20 7.5k
2002 Tahoe 5.3 153k 5w30 syn 7.5k
Re: 2012 Subaru Impreza Ft wh Bearing/Steering Knuckle [Re: deanm11] #4690563
03/10/18 01:48 PM
03/10/18 01:48 PM
Joined: Dec 2011
Posts: 266
Northern NJ
deanm11 Offline OP
deanm11  Offline OP
Joined: Dec 2011
Posts: 266
Northern NJ
Bump on a 2-year old thread /bearing repair.

The same right front is failing again. Miles were a little short of 70k then, a ~10k used one went in and now we're at just over 120k miles.

This time it isn't failing in as spectacular a fashion. You might mistake it for tire noise- it is most noticeable at 30-40mph.. at higher speeds the general road/tire noise overwhelms it and it isn't one of those horrific low speed bearing noises. I also just recently replaced the original front hubs on my '02 Tahoe and they were also not super noisy or groaning, but causing substantial front tire wear... so I'm more aware that bearings wear and fail in different ways.

I kept the original complete knuckle so I'm going to first install the SKF hub assembly ($115 shipped, Rock Auto) in that knuckle and then R&R the knuckle like I did last time.

Last edited by deanm11; 03/10/18 02:04 PM.

2012 Subie Impr 2.0 99k M1EP 0w20 7.5k
2002 Tahoe 5.3 153k 5w30 syn 7.5k

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