why do wheel bearings come loose?

My 2c on oil lube:

I changed my Disco to oil lube wheel bearings and since doing that I substantially over fill the rear diff by jacking up the driver side of the diff while filling. My theory is that gets oil at least to the passenger side while filling, then I just jack up the other side, or drive up a gutter or something. Bingo, both sides lubed.

You could just put oil in each hub and fill diffs to normal level, but for the cost of a few litres of oil, I think overfilling is a MUCH safer bet.

I slightly over filled the CV's as well, but visually, the level plug appears just high enough to fill the hub anyway, so not such an issue here - as long as you check the level again after a drive as some oil will migrate and level may go down.

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Originally Posted by Judo

My 2c on oil lube:

I changed my Disco to oil lube wheel bearings and since doing that I substantially over fill the rear diff by jacking up the driver side of the diff while filling. My theory is that gets oil at least to the passenger side while filling, then I just jack up the other side, or drive up a gutter or something. Bingo, both sides lubed.

You could just put oil in each hub and fill diffs to normal level, but for the cost of a few litres of oil, I think overfilling is a MUCH safer bet.

I slightly over filled the CV's as well, but visually, the level plug appears just high enough to fill the hub anyway, so not such an issue here - as long as you check the level again after a drive as some oil will migrate and level may go down.

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Bearings are supposed to be greased on assembly to ensure initial lubrication, but overfilling is hardly necessary unless you drive slowly enough round all corners to avoid sideways movement of oil and avoid roads with camber in either direction.

John

^ From memory I still put a slither of grease on as well. Just not anywhere as much as for greased lube only. :)

I have been told some greases do not play well with some oils. I dont see the problem with pre lubing them with the oil that is going in the housing. Is there any thought that this not enough? While I havent done many of these (clearly) I have done 2 rear hub seals, 2 rear complete strip outs. No sign of cooking the bearings what so ever. In fact all the bearings I am/have replaced look like they would be good for another 300,000km.

I just pre-oil with the oil I'm using in the diff.

Never had a problem.

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Originally Posted by uninformed

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John, do you mean I should have bent that tab over further to the end of the flat it is on, or choose another flat on the right side?

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Bend the tab over to create firm contact with the end of the nut flat to ensure the possible rotation of the nut in the direction of loosening is minimised. See where the red arrow is pointing in the pic below.

If the nut can back off slightly, the pre-load will reduce.

http://www.aulro.com/afvb/attachment...1&d=1385170172

Thanks John, noted and done on the front end.

Match, or mix ok?

When I install these bearings, I'm always careful to match the cup and cone from one box. Marking the box for L/R in and out. Cups get seated all in one sitting.

This time I had a cone that would not fit over the left stub axle (lucky it was an outer, not the one dropped in before the hub seal!) I had to swap it for one of the others and use it on the other stub axle.

Is this a no-no?

Timken usually package cups and cones separately. So no issue with them.

In your case if the cup and cone came from the same manufacturer, and the manufacturer is known for their quality, e.g. timken, skf, fag, ntn, then I wouldn't stress, although I would try to match the cup with the cone from the same package.

Yes only Timken for me. They came matched in box. It was a matter of do what I did or strip the seal out of the hub and drift the cup back out and do the same with another one in the other hub. That did not seem like fun at all :D

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Originally Posted by Bush65

Timken usually package cups and cones separately. So no issue with them.

In your case if the cup and cone came from the same manufacturer, and the manufacturer is known for their quality, e.g. timken, skf, fag, ntn, then I wouldn't stress, although I would try to match the cup with the cone from the same package.

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Depends on how you order them. you can order Sets or parts....