Wheel bearings, grease........

[Engineer]

Ok, so many, many, many moons ago I was taught that whenever you repacked wheel bearings that upon reassembly you would fill the void in the hub between the bearing races with grease.

My engineering geared mind never questioned if doing this served a purpose, I just assumed that it had to be in there to supply the bearings with critical lube. I'm sure I rationalized the practice by assuming a combination of heat and centrifugal forces would magically cause the grease to creep into the bearing roller track.

Years ago I ran into an old timer who NEVER packed the hub with grease, only the bearings. He claimed the grease was always there when he tore it back down so it wasn't being used by the bearings anyhow.

So as I reflected on what he told me I concluded a few observations, and thus: 1) If there is enough heat to sufficiently raise the viscosity of the grease to make it flow you probably have smoke. 2) The design of the opposed tapered roller bearings and races is such that the side nearest to the grease is the smallest diameter and as such centrifugal force will only force the grease deeper into the void in the hub and not over the edge of the race to the rollers. 3) He was right, the grease was always there right where I put it when I tore the hub assembly apart.



So what are the opinions of the hive? Does the grease in the hub serve any purpose? Should we just repack the wheel bearings with a good quality high temp wheel bearing specific grease and forget the hub?

I know the individual who told me this only packed the bearings, never packed the hub and as far as I know never had a failure.

[LTZ C20]

Well see I've always figured the same, pack the space with grease and that's what I've always done. Soooo, this kinda throws a wrench into the gears. Have we all been doing it right or just wasting grease?

I hope this doesn't lead to questioning all the other standard practice things we do.

[XrayTedd]

Back when I was a teen my dad taught me the same thing. Although I did ask him "why?"
His response.... "no reason really"
Never really gave it much thought after that. Filling the hubs was just something I've always done. BUT I can tell you this. I've had the same jar of bearing grease sitting on my shelf for over 2 years now. At about $10 a jar, I can't say that I feel like I'd be saving anything by not doing it.....

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[VileZambonie]

The grease needs to be packed in the void to help prevent moisture from causing rust which will contaminate the bearings and also to aid in cooling and serves as a grease reservoir. 

[LTZ C20]

Right but like Eng said, if it's reservoir, how does grease get fed into the bearings.

[bd]

The grease needs to be packed in the void to help prevent moisture from causing rust which will contaminate the bearings and also to aid in cooling and serves as a grease reservoir.

X2 

Although cooling is a twist I don't recollect, grease in the void helps maintain grease in the bearings.  Think of it this way: as the hub spins, grease in the void will seek a uniform level around the inside of the hub.  As long as the level of grease in the hub is above the lips of the bearing races, grease will migrate toward and into the bearings as the hub spins.  Evidence for this is grease blowing past the inner seal and, in extreme cases, dislodging the outer grease cap if too much grease is packed into the hub.  Grease in the hub also improves moisture rejection in the rare instance that water intrudes past the inner or outer seals.

[Stewart G Griffin]

It's been so long, i don't remember, but i always go by what the service manual says, whatever that is.

[Blazin]

I don't "pack " the void full. I do slime the spindle up in good shape, and I slobber the inside of the hub in good shape. More for moiture resistance than extra grease for the bearings.

[VileZambonie]

You don't need to pack it full, it is recommended to fill it to the outside diameter of the races. Anything more is excessive and unnecessary.