Why do my rear wheel bearings keep running dry?

[8v-of-fury]

If you used grease from a grease gun then you'll kill the bearing.

Buy wheel bearing grease.  It may seem silly to buy a tub of special grease that will sit on the shelf for years just for one application but once you get your fingers in it you'll see what the difference is.  I had some quakerstate stuff that you'd swear was full of fibre cuz the polymer chains were so long.  When I pulled a gob apart it looked like hair or something but it was all grease.

What if my grease gun was loaded with high temp bearing grease?? It seems like it would be pretty useful in place of normal grease, so I may just use it in my grease gun from now on.

Bentley says to tighten them while rotating the wheel and then loosen until you can move the washer with a light push with a screwdriver.

Will do, thank-you. I don't have a Bentley, I don't feel I need to be spoon fed THAT much lol.

[R.O.R-2.0]

on non-driven wheels, there is an acceptable amount of play, at .003 - .005"

a bearing will die faster being ran tight, rather than loose..

[fatmobile]

 A loose bearing doesn't last long either but we aren't talking quantities without mentioning quantities.
 Did you put grease on the seal lips?
They need lubed or can get hot.
 I have never had a bearing go bad after tightening the bentley way,.. with more than just a little twisting pressure on the screwdriver.

[8v-of-fury]

I do believe my conclusion was fully supported by the incorrect grease used.

I had a bearing run dry and subsequently overheat and expand the bearing cage. Causing play and probably a spun race.

[R.O.R-2.0]

A loose bearing doesn't last long either but we aren't talking quantities without mentioning quantities.
 Did you put grease on the seal lips?
They need lubed or can get hot.
 I have never had a bearing go bad after tightening the bentley way,.. with more than just a little twisting pressure on the screwdriver.

the rear of these cars way like 400 lbs.. and i meant that they will last longer loose, than too tight..

i dont mean like overly sloppy loose, i just mean that the spindle nut isnt CRANKED down tight..

you can have 3-5 thousandths play at the tire, and still have the bearing last JUST FINE..

[clbanman]

The Bentley instructions for bearings have never made sense to me.   I've had lots of tapered roller bearing training from various manufacturers (Timken, SKF, NTN) due to their importance in our products, and we always preload them.   I can't find the exact graph, but a preload up to a certain point increases the life, but once you exceed that, failure occurs very rapidly.   If you are going to err, a little on the loose side is safer that a little too tight.   What I can't understand about the VW method is how loose the Bentley tells you to make them.   I'm used to North American cars, and there is always a torque value on the nut - effective preload.   

Per http://motionsystemdesign.com/mag/adjusting_tapered_bearings/:"Improper adjustment can cause either excessive tightness or looseness. Tightness results in excessive contact between bearing rollers and raceway, leading to higher temperatures, potential excessive loading, and premature bearing failure. On the other hand, excessive looseness can result in improper loading of bearing rollers, leading to more roller sliding or skidding and eventual premature failure. Looseness also affects application accuracy and noise."

http://www.cpannut.com/newFacts.html

http://www.skf.com/portal/skf/home/products?lang=en&maincatalogue=1&newlink=1_0_83

Bearings can be overgreased, and doing so will lead to rapid overheating and subsequent expulsion of grease due to increased pressure.

As previously mentioned, greasing the seal lip can help extend it's life.  Our seal supplier says that lubrication during assembly can almost double the life of the seal even though the grease will be expelled during operation.