repeat bearing failure 96 Leg/OB

[paulivan]

I replaced Rt front bearings not too long ago with a new (used) hub. The bearing failed within 3000 mi. Is this a sign of something else wrong?

 

I had machine shop press in the new bearing.

 

Are there some common errors during installation that would cause quick failure? --especially the hub install to axle part because I trust the machine shop, but who knows?

 

Any tips for my second time around?

 

I'm using Chilton manual as my guide.

 

cheers

[idosubaru]

you mentioned "new, used hub and new bearings" - i'm not sure i'm seeing exactly what you did.

 

if the hub is damaged it can ruin the bearings. i had the same thing happen, mine just lasted 5,000 miles instead of 3,000 :-\

 

i replaced the bearings and it failed again. next time i just installed a completely different used knuckle assembly. we'll see how long this one holds up

[paulivan]

I removed original hub and replaced with used hub and new bearing. Maybe I should just buy a new hub/knuckle like you did...or

 

do you think the machine shop could tell if something is wrong with the hub when I take it to get new bearing pressed?

[hohieu]

Just to clarify that we're all using the same terminology: the bearing presses into the knuckle, then the hub presses into the inner races of the bearing, and finally the axle runs inside the hub splines.

 

Did you repack the new bearing with a decent bearing grease? They come with packing grease intended to prevent corrosion.

 

Check that the polished surfaces of the outer half shaft joint are smooth and not pitted. Corrosion and pitting destroys the inner seal allowing grease to leak out and debris to enter.

 

Using a hydraulic press can sometimes deform a new bearing during installation. Pressing against the inner race during installation can do the same.

 

Finally, did you torque the axle nut properly with the front wheel off the ground?

Edited May 25, 2009 by hohieu
typo

[idosubaru]

i don't think the shop can test anything, i actually asked this question not too long ago and no one replied saying that there was anyway to verify the parts were good or not.

 

from my previous discussions with folks here, the hub needs to be replaced.

 

like he just mentioned, let's make sure we're talking about the same thing. the hub is the center part with the 5 lugs on it that's pressed through the bearings which reside in the knuckle.

 

some folks say "hub" in place of knuckle and in this case it would make things very confusing.

[paulivan]

That is a little confusing; if have it right then I ended up with the whole knuckle and hub assembly from the shop as one complete unit and installed that.

 

I'm pretty sure that i torqued the axle nut with wheel on the ground so maybe that explains the problem. The axle nut was a little loose when I checked things out after all the grinding and squeaking started.

 

Tough learning curve.

 

I guess I'll just take the hub and knuckle assembly back to the machine shop to press new bearings and try again, this time torquing axle nut with wheels raised. Shop told me not to add any additional grease when installing, something about bearings factory packed with special lube.

 

Any suggestions for keeping the wheel from turning while torquing nut? I read one post said put bar between two lugs and braced against ground, is that safe for the lugs?

 

Thanks for help.

[hohieu]

All dealer techs, including a master tech at a dealer shop managed by a friend of mine have recommended repacking the bearings, even the OEM rear wheel bearings on my car, which Subaru of America explicitly says not to repack.

 

I always repack them for peace of mind:

 

Remove the keeper from bearing, being careful not to drop the inner races, which will then just fall out. Wipe off the old grease and clean thoroughly with non-chlorinated brake cleaner. Allow to dry or blow dry with compressed air. Then pack 30% of the free space inside the bearing with a decent grease. I use the Mobil 1 red grease because it's relatively inexpensive and widely available.

 

The method mentioned for tightening the axle nut will work just fine. You could wrap the lug nut studs with a short section of hose to avoid buggering the threads. Just be careful as you're cranking it down. For my car, the shop manual calls for 137 +/- 14 ft.-lbs.

[paulivan]

Does that grease packing method apply to the 96 legacy outback?

I've seen in the manual that there are two types of bearing depending on model, one is tapered the other is not.

 

Just want to be sure its the same; is yours a tapered bearing? I'm not sure I could pack my bearings like you describe.

[tcspeer]

I purchase my parts from Litha Subaru in Or. They also told me the grease in the bearing is ready to install, But I still clean mine out and repack with Hi Temp disc brake bearing grease.

 

If you want to repack your own bearings do a seach on the web, I have seen a demonstration of how it is done there, but dont remember the link.

[hohieu]

Does that grease packing method apply to the 96 legacy outback?

I've seen in the manual that there are two types of bearing depending on model, one is tapered the other is not.

 

Just want to be sure its the same; is yours a tapered bearing? I'm not sure I could pack my bearings like you describe.

 

Yes, tapered roller bearings in both the front and the rear of my car. So certain trims of '96 Legacies used caged ball bearings in the front? In any case, it makes no difference because the bearings will disassemble in the same way.

 

You just need to push the plastic retainer out, and the bearing will come apart in 3 pieces: 2 x inner races with the caged rollers and 1 x outer race. Just be sure to work on a flat surface as to avoid dropping the inner races after the retainer is removed.

Edited May 25, 2009 by hohieu

[CNY_Dave]

Having just domne my '03 front bearings on one side, there are 3 critical items (aside from grease)

 

1) the hub has to be cherry. No marks that go around it in a circle, no discolorations from heat, no lip no matter how small.

 

2) when pressing in the hub the inner race of the bearing on the bottom of the assembly must be well supported.

 

3) Torquing the axle nut is more important than you might think- must be done with no weight on the bearing (according to the service manual) and you have to turn that thing for a seemingly long time to draw the two inner races together on the hub. The suybaru tool does this, I think, but if you use a press the races are not in position until the nut stops turning and reaches the full torque value (very soon after it stops turning har5d, but smoothly with no torque increase as you turn it).

 

 

Dave