Wheel bearing life extended by periodically repacking?

[zKars]

John, wise and experienced thoughts indeed. No surprise that we are overthinking this. Buy the best grease you can find, pack your bearings properly, throw some in the housing if you feel like it, and forget it about for 10 years.

Yet I can almost guarantee you that at least three of "us" will now go and mock up an experiment with a rear axle housing and freshly packed bearings, where a propane torch and an electric motor are involved. They will measure 3D grease displacement at varying temperatures and centrifigal force values, and will plot the results in an excel spreadsheet. Only they will find that no matter what they do, the grease just stays in the bearings.... like its designed to do....

[EuroDat]

This is work related and a bit off topic, but I still think its worth mentioning.

We had Electomotors with grease nipples to gease the bearings in our water treatment plant. The technicians greased them in there rounds with 3 grams of grease as per manufacurers instructions. These motors where installed in 1998 and were all replaced by 2002 mostly due to bearing failure.

I had them replaced with motors that had sealed bearings filled with Hi-temp grease. Nearly all (14 of the 15) are still in use today, but some are starting to develope signs of bearing wear that shows up in the vibration analysis we do every six months. These motors run all day every day for Purified water, WFI, and Cooling / heating medium systems.

My conclusion; A sealed bearing lasts longer because it does not get contaminated by dirty grease or when someone pumps in to much grease and pops the dust seals allowing dirt and other contaminates in.

Common causes for bearing failure is contamination or undersized / underrated where the pressures in the bearing increases above the design limit and causes it to overheat at which point the grease fails to lubricate and it fails.

I think lubricating them could reduce there life span more than increase it. Like John said in his post, most rear wheel bearings last the life of the car or at least 100,000miles without relubricating.

Chas

Edited July 9, 2014 by EuroDat

[240260280z]

geeks unite

[Captain Obvious]

I've thought about what the grease does at high temps and spinning as well, and I've come to the same conclusion as John Coffey. I don't think it goes far and it certainly doesn't liquefy. When I took my old rear wheel bearings out, it was clear that the grease never left the immediate areas of the bearings. There wasn't a lot in there and it was all located by the bearings. I had to use mechanical means to remove it.

When I put my bearings back together, I packed the entire recess completely full on the first one. Took about half a tub of grease. a strikingly large amount.

After I got done with the assy, I tested the turning torque required to spin the hub, and it was too much. I didn't measure it, but clearly way more force than it should take to spin. Like the grease was trying to get out of the way of the balls, but just had no place to go.

When I did the second hub, I packed the balls with grease and a little extra and put the thing together. Felt just like I would have expected it to.

So based on those results, and because of where I found grease on the original bearings when I did the disassembly, I took the first side apart, scooped out most of the grease and put it back together again. Feels perfect and matched the other side.

[bpilati]

Why bother greasing the rear bearings when they last so long? Unless it's a daily driver they'll last over 40 years like mine.