What's the deal with wheel bearings?

Discussion in 'On The Road' started by Andy G., Oct 20, 2018.

  1. WrkrBee

    WrkrBee Well-Known Member

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    I get blow back when I rank EZ Lube hubs down there with particle board.
     
  2. Adam H

    Adam H Active Member

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    Previous owner lubed them wrong or the incorrect grease seal was installed. Bet he just gave them a few squirts yearly without spinning the wheel...
     
  3. WrkrBee

    WrkrBee Well-Known Member

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    You can have the correct seal. The back seal is not a pressure seal. EZ Lube has to develop pressure to push grease through the bearings, even when turning the wheel. I'll stop there.
     
  4. Adam H

    Adam H Active Member

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    Can you tell me the difference between a pressure seal and the seal used on the EZ Lube axles?
     
  5. WrkrBee

    WrkrBee Well-Known Member

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    Probably not. There are thousands of pressure seal designs and I'm sure hundreds of wheel bearing seal designs. They are all designed for particular application ranges and pressures. Going to the Dexter website, their seals look like most other wheel bearing seals. Thinking about the application, how much pressure is generated by hand packed bearings while towing?

    Now EZ lube- look at the videos of guys replacing their grease the first time. Pump and spin, pump and spin. They pump in half a tube of grease to see any movement. Dexter says not to use a power grease gun to speed up the process (really too much pressure). So the Dexter axle comes with only greased bearings. If the EZ lube system is so great, why doesn't it come from the factory full of grease?

    I've seen over greased bearings stop an industrial machine. A new mechanic pumped the bearings full. Machine shaft got hotter and hotter churning that grease and finally stopped the drive. We figured it out and when the Zerk fitting ball was unseated, grease streamed out like a big zit. It oozed for hours.
     
  6. Adam H

    Adam H Active Member

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    Answer: no difference, the seals are the same design. The only difference is single or double lip.
    If it built enough pressure bind down the bearings, certainly the rubber cap on the outer cover would pop off long before the seal leaks.
    I have seen several times where people have just "given the hubs a squirt or 2" once a year or before long trips without spinning the wheel, that's where they run into trouble.
     
    Last edited: Aug 27, 2019
  7. WVhillbilly

    WVhillbilly Well-Known Member

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    But look how long the brakes lasted.
     
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  8. Anthony Hitchings

    Anthony Hitchings Active Member

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    All you get is hot grease; worst case it that it finds some way to escape to some place you don't want it.
     
  9. WrkrBee

    WrkrBee Well-Known Member

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    Hot grease is not the worst case. Info from three different sources.

    machinerylubrication.com/Read/28664/dangers-of-overgreasing-
    When it comes to regreasing bearings, more is not always the better option and actually can be a costly mistake. Overgreasing can lead to high operating temperatures, collapsed seals, energy loss, and failures.

    Too much grease volume (overgreasing) in a bearing cavity will cause the rotating bearing elements to begin churning the grease, pushing it out of the way, resulting in energy loss and rising temperatures. This leads to rapid oxidation (chemical degradation) of the grease as well as an accelerated rate of oil bleed, which is a separation of the oil from the thickener.

    The heat that has been generated over time along with the oil bleed eventually will cook the grease thickener into a hard, crusty build-up that can impair proper lubrication and even block new grease from reaching the core of the bearing. This can result in accelerated wear of the rolling elements and then component failure.

    MaintWorld
    Too much grease builds pressure, pushing the rolling elements through the fluid film and against the outer race. The bearing now has to work much harder to push the rolling elements through a mud bog of grease.

    The increased friction and pressure from too much grease raises the temperature inside the bearing. Excess heat could decrease the effectiveness of the lubricant causing the oil to separate from the thickener. Not adding enough grease has the same life-shortening effect.

    Seal damage is another negative side effect of overgreasing. Grease guns can produce up to 15,000 psi, and when you overgrease a bearing housing, the lip seals can rupture, allowing contaminants such as water and dirt to gain access into the bearing housing. Keep in mind that lip seals usually fail around 500 psi.

    Bearingsinc.info
    Overlubricating your bearings can cause the balls or rollers to slide along the race rather than turning. Then, the grease could actually churn. This churning mechanism could ultimately bleed the base oil from the grease.

    What will remain to lubricate the bearing is a thickened system with little or no lubricating elements. Since there is not enough lubricating oil, and there’s excess heat from the churning, the grease would start to harden. The final outcome is bearing failure and equipment downtime.

    Seal damage is yet another negative side effect of too much lubrication. When there is abundance of pressure from a grease gun caused by overgreasing, the crusty grease tends to be broken apart and goes straight off to the bearing track.
     
  10. Econ

    Econ Active Member

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    I'm weird. I like my brake shoes to wear. Especially in sharp curves.
     
  11. Jack Sprat

    Jack Sprat New Member

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    L
     
  12. Jack Sprat

    Jack Sprat New Member

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    I recommend when you check for bearing/wheel heat that you feel with the back of your hand. Slowly approach the bearing and feel for radiant heat first. If you burn the back of your hand it won't affect usage of hand as bad as a burn in your palm. Best tool would be a point and shoot thermometer.
     
  13. Adam H

    Adam H Active Member

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    My “overpacked” hubs are never more than a few degrees above ambient.
     
    Last edited: Sep 1, 2019
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  14. Jack Sprat

    Jack Sprat New Member

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    I agree with you Adam. I use Buddy Bearings on every trailer I have. I have 5 trailers. I've only had one bearing go out. So hot it blew the tire. It was a dry bearing that caused it. My bad. I've never had it happen since the use of BB.
     
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