Spindle Bearings

[GearHead36]

Grease not getting past sealed bearings.... In this video, this guy disagrees that bearing seals will block grease from getting to the bearings, and he demonstrates his findings. The seals CAN block the grease if you don't apply grease correctly, and he shows how to do it correctly. The trick is, you have to pump in enough grease to fill the spindle, then pump some more until some squirts out each end. That ensures that grease made its way through the bearings on each end. If you pump in what seems like a normal amount, the spindle won't be full, and if you have sealed bearings, they won't get any grease. It takes a lot of grease to fill a spindle. I have a low end commercial ZTR. I bought it with about 400 hrs on it. When I serviced the deck, I found that none of the spindles were dry, but also, none were full of grease. Two were fine, but one had a lot of play and a lot of wear. I replaced it. I then greased my spindles as the guy in the video recommends. That was only about 30 hrs ago, so I don't have any long term results.

 

[woodstover]

Grease not getting past sealed bearings.... In this video, this guy disagrees that bearing seals will block grease from getting to the bearings, and he demonstrates his findings. The seals CAN block the grease if you don't apply grease correctly, and he shows how to do it correctly. The trick is, you have to pump in enough grease to fill the spindle, then pump some more until some squirts out each end. That ensures that grease made its way through the bearings on each end. If you pump in what seems like a normal amount, the spindle won't be full, and if you have sealed bearings, they won't get any grease. It takes a lot of grease to fill a spindle. I have a low end commercial ZTR. I bought it with about 400 hrs on it. When I serviced the deck, I found that none of the spindles were dry, but also, none were full of grease. Two were fine, but one had a lot of play and a lot of wear. I replaced it. I then greased my spindles as the guy in the video recommends. That was only about 30 hrs ago, so I don't have any long term results.

Waaaaaaaaay back in time when I was apprenticing automotive, at school the rule was not to overpack grease in wheel bearings, etc meaning pack the bearings properly, apply a thin coat on hub & spindles to prevent corrosion only as it causes heat retention and causes premature bearing wear due to heat. Overpacking a spindle to the point that it oozes out each end to me suggests that the grease is insulating and not allowing ambient air to cool the spindle housing as a whole. Also the waste of grease. Just my 2 cents.

 

[GearHead36]

Waaaaaaaaay back in time when I was apprenticing automotive, at school the rule was not to overpack grease in wheel bearings, etc meaning pack the bearings properly, apply a thin coat on hub & spindles to prevent corrosion only as it causes heat retention and causes premature bearing wear due to heat. Overpacking a spindle to the point that it oozes out each end to me suggests that the grease is insulating and not allowing ambient air to cool the spindle housing as a whole. Also the waste of grease. Just my 2 cents.

I'm going to disagree that air cools better than grease. Grease will conduct heat way better than air. Wheel bearings have to be removed to be greased. They typically don't get greased through zerk fittings. Any assembly with a zerk fitting (ball joint, tie rod, etc) gets filled until grease comes out somewhere, or until you can feel the boot start to bulge.

 

[Tiger Small Engine]

I'm going to disagree that air cools better than grease. Grease will conduct heat way better than air. Wheel bearings have to be removed to be greased. They typically don't get greased through zerk fittings. Any assembly with a zerk fitting (ball joint, tie rod, etc) gets filled until grease comes out somewhere, or until you can feel the boot start to bulge.

Most people are not going to remove a bearing in a spindle to pack it, before installing it. Nobody is going to remove the bearing once the spindle is installed to pack it at a later date. Pump the spindle full until it comes out is the only practical way. It can take 100-150 pumps sometimes.

 

[ILENGINE]

Waaaaaaaaay back in time when I was apprenticing automotive, at school the rule was not to overpack grease in wheel bearings, etc meaning pack the bearings properly, apply a thin coat on hub & spindles to prevent corrosion only as it causes heat retention and causes premature bearing wear due to heat. Overpacking a spindle to the point that it oozes out each end to me suggests that the grease is insulating and not allowing ambient air to cool the spindle housing as a whole. Also the waste of grease. Just my 2 cents.

That was the concern with overpacking wheel bearings. The extra grease causes heat retention leading to premature bearing failure.

I'm going to disagree that air cools better than grease. Grease will conduct heat way better than air. Wheel bearings have to be removed to be greased. They typically don't get greased through zerk fittings. Any assembly with a zerk fitting (ball joint, tie rod, etc) gets filled until grease comes out somewhere, or until you can feel the boot start to bulge.

You are correct that the grease will conduct heat better than the air, but the issue that @woodstover is trying to bring up is that grease also retains the heat longer. Which is/was believed to lead to premature bearing failure. And also the reason most sealed bearings don't appear to have enough grease installed from the factory.

And something I just thought of was what type of grease is being used in sealed bearings. Are they using urea based grease, and then we are pumping the spindles and bearings full of lithium based grease, and the 2 greases are incompatible with each other leading to early bearing failure.

 

[GearHead36]

That was the concern with overpacking wheel bearings. The extra grease causes heat retention leading to premature bearing failure.

You are correct that the grease will conduct heat better than the air, but the issue that @woodstover is trying to bring up is that grease also retains the heat longer. Which is/was believed to lead to premature bearing failure. And also the reason most sealed bearings don't appear to have enough grease installed from the factory.

I'm having a hard time understanding how this could be. I'm not saying that it's impossible, but I'd like to see proof.

And something I just thought of was what type of grease is being used in sealed bearings. Are they using urea based grease, and then we are pumping the spindles and bearings full of lithium based grease, and the 2 greases are incompatible with each other leading to early bearing failure.

I hope that's not the case. I recently replaced a spindle, and filled it with Lucas Red n Tacky.

 

[ILENGINE]

@GearHead36 I don't know if it was a proven fact or some word of mouth that spread about, with the original reason being trying to save grease. But back when I was playing mechanic on M813A1's, it was taught to not fill the wheel spindles full of grease because it caused the hubs to run hotter. Which may not of lead to bearing failure, but would take longer to cool back to air temperature because of the retained heat in the grease.

The green urea based grease thought came about because of the replacement bearings on my nephews stump grinder wheel shaft. We have always used the lithium based greases on that machine, but when doing the last replacement and following the bearing manufacturer instructions it was noted that the bearings are packed from the factory with urea base grease.

 

[GearHead36]

@ILENGINE, I'm no expert in the matter. I'm not a petroleum engineer. I AM an engineer (electrical) and a gearhead (my dad was a professional mechanic), so I'm not totally clueless. But also, my career as an engineer has taught me that I don't know everything. For the assemblies that get filled with grease (ball joints, tie rods, etc), they are typically NOT rotating assemblies. Bearings on rotating assemblies, like wheel bearings, typically get removed and repacked. So I don't know the answer on this one. Filling the spindle until grease squirts out WILL put grease in the bearings, but is filling the spindle going to cause other problems? I don't know. I would like to think that some engineer somewhere knew what he was doing when he put a zerk fitting on his spindle design. Testing this sounds like a mission for Project Farm.

 

[ILENGINE]

@ILENGINE, I'm no expert in the matter. I'm not a petroleum engineer. I AM an engineer (electrical) and a gearhead (my dad was a professional mechanic), so I'm not totally clueless. But also, my career as an engineer has taught me that I don't know everything. For the assemblies that get filled with grease (ball joints, tie rods, etc), they are typically NOT rotating assemblies. Bearings on rotating assemblies, like wheel bearings, typically get removed and repacked. So I don't know the answer on this one. Filling the spindle until grease squirts out WILL put grease in the bearings, but is filling the spindle going to cause other problems? I don't know. I would like to think that some engineer somewhere knew what he was doing when he put a zerk fitting on his spindle design. Testing this sounds like a mission for Project Farm.

Agree, The word if true or not about filling housings is anedotal at this point. One source says to not fill a wheel bearing spindle full of grease because the extra heat retention could cause problems. Then there are several trailers with greasable spindles that you are suppose to replace the grease in the spindle every 3000 miles by pumping grease into the spindle until grease comes out clean, basically replacing all the grease in the wheel bearing housing

 

[Auto Doc's]

I have learned that the more I think I know, the more I really have yet to learn.

For many years, when I overhaul a deck or replace a spindle, I open the new ones to pack the bearings manually to ensure they have enough extreme pressure (EP) grease. I have always had a great service history using Mystic JT 6 Red EP Grease