Sealed wheel bearing question

[Greenley]

When using sealed bearings, do you still pack grease into the knuckle the same as you would with open bearings?

[bratman18]

When using sealed bearings, do you still pack grease into the knuckle the same as you would with open bearings?

 

On the sealed ones I used, I decided to check to see what was in them for grease. I popped the seal open and there was VERY little grease!!! I packed them, popped the seals in and called it good. I don't think I put any grease in between though. And they have been good for a couple years now.

[GeneralDisorder]

DO NOT repack sealed bearings. They do take *very* little grease. This is by design as they do not exchange grease with a larger bearing cavity. The grease needs airspace to expand as it warms to it's dropping point. If you pack them solid the grease will simply overheat, cook itself, and fail - contaminating the bearing and causing premature failure. Also - unless you first flush them very well with solvent, wash them with soap and water, and regrease them you have no idea if the grease used by the manufacturere is compatible with the grease you are packing them with. The result could be anything from the grease losing it's lubrication properties, never dropping at all, to just turning to plastic.

 

Greenly - YES - apply grease to the outside of the bearings and the lip seals. If the lip seals do not have lubrication they will fail in short order. I put the normal amount of grease between the bearings as well. This just serves to trap particulates and moisture that gets past the seals and also keeps the bearing pockets from corroding.

 

GD

Edited October 21, 2009 by GeneralDisorder

[DanMac]

DO NOT repack sealed bearings. They do take *very* little grease. This is by design as they do not exchange grease with a larger bearing cavity. The grease needs airspace to expand as it warms to it's dropping point. If you pack them solid the grease will simply overheat, cook itself, and fail - contaminating the bearing and causing premature failure. Also - unless you first flush them very well with solvent, wash them with soap and water, and regrease them you have no idea if the grease used by the manufacturere is compatible with the grease you are packing them with. The result could be anything from the grease losing it's lubrication properties, never dropping at all, to just turning to plastic.

 

Greenly - YES - apply grease to the outside of the bearings and the lip seals. If the lip seals do not have lubrication they will fail in short order. I put the normal amount of grease between the bearings as well. This just serves to trap particulates and moisture that gets past the seals and also keeps the bearing pockets from corroding.

 

GD

 

I STRONGLY disagree with that. Use an o-ring pick and carefully remove the covers, clean them thoroughly as you would with any other bearing before packing, then pack them as any other bearing, replace the covers and your bearing is set for a much longer life than the original. Done it many, many times and never had to replace one again after that.

[GeneralDisorder]

I STRONGLY disagree with that. Use an o-ring pick and carefully remove the covers, clean them thoroughly as you would with any other bearing before packing, then pack them as any other bearing, replace the covers and your bearing is set for a much longer life than the original. Done it many, many times and never had to replace one again after that.

 

Other than having done it "many, many times" (anecdotal evidence at best without *at least* usage information both pre and post replacement), do you have any good reason to be repacking sealed bearings? What evidence can you show that proves they wouldn't have lasted just as long or longer had you not repacked them? Do you still have or keep track of all these bearings you have replaced? Lets not forget that most EA wheel bearings have already lasted more than half the life of the car before needing replacement - ONE replacement is most often all that is needed for the remaining life of the automobile and that lifetime is often considerably shorter than the factory set.....

 

My reasoning is backed up by industry standards and tons of research into the subject by the nuclear power industry, NLGI, and others. Not to mention my own experience. And lets not even go into the damage you can cause to the seals by removing and installing them with a pick.

 

Don't screw with sealed bearings unless you plan on leaving the seals out - often bearing houses will only carry 2RS bearings and tell you to pull the seals if you want an open, greaseable bearing for your application so that's not uncommon to pull them. But you don't put them back in - that's a no-no for a number of reasons.

 

GD

[bratman18]

Well I'm sticking to repacking them. I went through 3 sets of the sealed ones before I opened them up. I found very little grease. I cleaned them and packed them as I have with the normal ones, and have put many miles on them without any issues!! I also have a friend that started using them after this. He has put even more miles on his without any issues. I understand the whole thing where the grease needs room to expand because of the heat, but in this case I found otherwise with proven results.

 

And just so you know GD, I fully respect you and what you have to say, You definitely know a great deal and have helped a lot!! I'm just goin off what I have found.

[GeneralDisorder]

Let me just say I'm really glad you won't ever work on any of my cars. I'll just leave it at that. I was young and full of myself at one time too.

 

We can dissagree about bearing greasing. It's ok. Lots of people dissagree with it.

 

I get flak for my posistions on greaseing every time I voice them. There is a lot of old "wisdom" on the subject that is ingrained in the older generation as most have not kept up with the literature on the subject, are not aware of the changes in qualities of lubricants, and very much *want* to beleive they are still doing it right.

 

I want to draw your attention to some documents from my library:

 

 

Here's some facts:

 

1. At 60 MPH, an EA series wheel bearing spins at ~870 RPM.

 

2. The 6207 has an inner bore diameter of 35mm.

 

3. Due to the resolution of this chart, I chose a 40mm bore and a 1000 RPM speed to insure that I underestimate the usable life of the bearing grease.

 

4. The chart indicates a usuable grease life (when the grease should be serviced), of 20,000 hours.

 

5. If every single hour of operation were @ 60 MPH, that works out to 1,200,000 miles for the usable life of the grease.

 

If you even got HALF that number of miles (possibly due to higher temps from excessive braking, lots of stop/go style driving, etc) you would be exceeding the usable life of the car by several times over in most cases.

 

Please take note of the paragraph under "How long does the grease remain usable?". It notes that:

 

...the service life of the grease is in many cases so long that no relubrication is neccesary. In such cases, ball bearings lubricated for life, fitted with sheilds or seals may be suitable

 

I must emphasize that this paragraph implicitly indicates that most bearings fitted with sheilds or seals ARE lubricated for life. Such is the case with all the one's I've seen so emperical evidence would seem to validate.

 

ALSO I would draw your attention to the grease compatibility matrix. Notice all the red? That's because you can't just mix grease types in most cases. Thus EA series wheel bearings can NEVER be regreased as it will damage them to remove and reinstall them and there is no other way to flush the old grease out. Plus if you just smear new grease in there - even if it's compatible you are contaminating it with the old grease and the contaminates already present. They are not timken roller bearings and can't be treated as such. If they were, you would (should) be repacking them every 120,000 miles (by the chart - probably it would be reccomended more often than that to be safe). The same does not apply to ball bearings - the forces applied to the bearing surfaces and the grease are different. This ain't your daddy's Chevy truck.

 

It's also a really poor idea to flush brand new bearings, repack them, and reinstall the seals - you risk contamination from the solvents and any remaining bits of the OEM grease. It's also very hard to insure you have applied *just* the right amount so the bearing receives correct lubrication without overheating.

 

GD

Edited October 23, 2009 by GeneralDisorder

[The Dude Abides]

I dont know if your new to subarus or not, but i would listen to what GD says. Forget about wht you know. Forget about almost everything you know about cars. These things are totally different. Its exactly like he said, this aint your daddys chevrolet.

[subguy]

When using sealed bearings, do you still pack grease into the knuckle the same as you would with open bearings?

 

Yes, pack the new bearing w/ a wheel bearing grease. You can push the inner race and bearing/roller cage from the center and seperate from outer race. There will be a plastic retaining sleeve between the to halves thats there for shipping purposes only.

[GeneralDisorder]

could you explain the 's' ratings you've mentioned?

 

I think you are refering to the "C" clearance number of the bearing yes? Here's a good tutorial on the subject. Subaru wheel bearings are C3's. Unmarked bearings are typically CN which is some nebulous clearance between C2 and C3 according to this document. Might be ok, but then again maybe too tight.

 

http://www.ahrinternational.com/bearing_radial_clearance_explained.htm

 

I prefer to stick with SKF, NTN, FA G (no space), and the other big-name bearing suppliers. Qaulity of construction and inspection seems to be lacking on the cheap stuff.

 

GD

[GeneralDisorder]

I've said my peice freind. Take it or leave it. I type VERY fast (also a software engineer) so it's no trouble at all to go on. But it's clear that it's wasted on you. Good laugh for me and the crowd though. Hope you're stocked up on the blood pressure meds if you are going to stick around.

 

GD

[DanMac]

You're a good sport GD. Have a great night.

[Txakura]

I think you are refering to the "C" clearance number of the bearing yes? Here's a good tutorial on the subject. Subaru wheel bearings are C3's. Unmarked bearings are typically CN which is some nebulous clearance between C2 and C3 according to this document. Might be ok, but then again maybe too tight.

 

http://www.ahrinternational.com/bearing_radial_clearance_explained.htm

 

I prefer to stick with SKF, NTN, FA G (no space), and the other big-name bearing suppliers. Qaulity of construction and inspection seems to be lacking on the cheap stuff.

 

GD

 

 

yes, thanks - that was it, despite my confusion over the alphabet

 

great post with the charts, reminds me of an aircraft structural repair manual (SRM) or maintenance manual (MM)

Edited October 24, 2009 by Txakura

[calebz]

The thread has been reported.

The information, disseminated.

 

Going to close this one.

 

Normally I would take this opportunity to tell GD to back off a little, but this time he stuck mostly to the facts.

 

New guy, I don't know you. I do know GD. He is obnoxious. He is condescending. He is also right more often than not.

 

You on the other hand are an unknown. If you like it here my recommendation would be to either stay unknown and lurk, or pick your e-battles more carefully and with more considered response.

[Qman]

GD, you know the rules of engagement...

 

DanMac, your new here, the rules of engagement(debate) attack the idea not the person.

 

Everyone else, I blame you more than both of them. I have editted the stupid out of this thread. If your post isn't here anymore then you should now know.