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ANOTHER forester wheel bearing.


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2008 NA Automatic 95k. This is the fourth on the right front. I may have been wrong about one of them, but this one is def going to go.

If they overheat JUST ONCE, they are goners.

 

I pull off the expressway for 2 minutes, which gives it enough time to cool off and shrink. Then I can drive 65.

 

POS.

 

I've trusted my shop to pick a bearing, and I think they use National. I have an NTN I'm going to try this time.

 

On my commute home I have a long high-speed left sweeper entrance ramp. I guess this car isn't designed for that.

Edited by uniberp
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Torque spec is very important on these bearings. Over tightening will overheat the bearing.

Under tightening doesn't put enough pre-load on the bearing and causes uneven weight distribution on the rollers.

That's the first time I've heard that. So there's a crush-expand specification on the inner race?

Spec is 137 ft lbs on the axle nut. 

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can you be more specific about this 'tightening-up/shrinking' statement?

 

I'm just presuming that the normal physical laws apply: heat expands- cleareances tighten. I've got a pic of a burnt bearing in some other thread. I'm pretty sure I'm not tightening the axle nut to the exact 137 lb ft, but I've done many crank pulleys and axles and bearings on other Subes, WITHOUT FAILURE.

 

I know what this bearing race will look like when it's punched out.

 

I wonder if these wide (stock) 16 wheel/tires abosrob less shock or are otherwise less forgiving  that my old 14 Legato wheels or the 99 Forester 15's

 

I'm beyond being mad about these dumb things, just annoyed.

Edited by uniberp
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Have you replaced the hub yet?  If you haven't, get a bearing/hub assembly next time.  The hub will be separate but they are cheaper bought together than separately.

 

If you have replaced the hub at least once, you may need a new steering knuckle.

Edited by keith3267
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I think the risk from overtorque is from distorting the races, severe risk from undertorque or putting weight on it before torquing.

 

No crush, just 2 races meeting face on setting the race-race clearance just a wee bit smaller than the ball diameter.

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I think the risk from overtorque is from distorting the races, severe risk from undertorque or putting weight on it before torquing.

 

No crush, just 2 races meeting face on setting the race-race clearance just a wee bit smaller than the ball diameter.

These are cartridge bearings, fixed race spacing. I don't think you could distort that inner race with 1000 ft lbs of torque. All Subes are pretty much the same that way I think. 137 pounds is just safety so you can use right hand threads all around.

 

I took the hub off, the bearing is stiff. I have a new cartridge, it is not as stiff. The only other thing I think I may have done wrong is use too much antisieze on the spline, and a small amount got into the bearing and cooked. I'll ask the machinist tomorrow.

 

I should say, each time I do this I remember why I hate it: It's separating the balljoint tapers. That sukz.

Edited by uniberp
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Yes they're "fixed" spacing, but the bearing races are not as tough as you think. They don't "crush", but they are distorted by torqueing the axle nut. A certain amount of that flex is planned for in order to set the preload on the bearing. Too much flex overloads the bearing.

 

Bearings need to be torqued to spec with the wheel off to avoid damage.

 

Antiseize shouldn't cause an issue unless you're getting a LOT of it inside the bearing.

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I've torqued many of these on the ground, never had an issue. It shouldn't matter as long as you get it snug before you let the weight down on it. I was always told not to use and impact on these even to snug them up because it can cause deformation of the bearing.

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4 failures is insane.

 

***** Replace the hub *****  

IMO that is the first step if you're having repeat failures.

 

Well the first step is knowing a little bit about the vehicle/situation:

Does the vehicle have any accident history?
Have you owned it since new?
If not, have you done a carfax on it?

 

Sure I'd go for a high quality bearing, but I would guess if you look at the reviews of whatever bearing you used - they're not likely having bazillions of failures.  They'd need to have a huge failure rate to conceivably have 4 in a row.


Is the mating surface for the wheel perfectly flat?  I've seen sheared off brake retaining screw nubs sticking out of the rotor cause wheel bearing failure and lug nuts to shear off.

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4 failures is insane.

 

***** Replace the hub *****  

IMO that is the first step if you're having repeat failures.

 

Well the first step is knowing a little bit about the vehicle/situation:

Does the vehicle have any accident history?

Have you owned it since new?

If not, have you done a carfax on it?

 

Sure I'd go for a high quality bearing, but I would guess if you look at the reviews of whatever bearing you used - they're not likely having bazillions of failures.  They'd need to have a huge failure rate to conceivably have 4 in a row.

 

Is the mating surface for the wheel perfectly flat?  I've seen sheared off brake retaining screw nubs sticking out of the rotor cause wheel bearing failure and lug nuts to shear off.

Maybe it was 2 failures. with at least a year inbetween. 1 I may have id'd the wrong side. Machinist say the hub and knuckle are round and parallel. If anything the torque was below spec, but when I took the hub off the bearing was tighter than new. It only vibrated two days so I didn't cook it brown.

Bought the car new. 

Got this one done now. This bearing is an SKF. First was OEM and National.

At any rate see you in a year about this I hope not .

Edited by uniberp
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