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Old 04-06-2016, 09:04 AM   #15
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Most of us will pull the hubs annually to inspect the brakes and do a repack then. I just replaced all my brake assemblies and installed new bearings in new hubs so I will inspect next winter but probably not repack unless there is something amiss.

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Old 04-06-2016, 01:27 PM   #16
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Originally Posted by bwoodtx View Post
Is there any justifiable reason to pack the center cavity full of grease when doing a repack and brake job.

Seems like a waste to me.
Industrial maintenance experience and articles by bearing manufacturers, lube manufacturers etc, have convinced me that a big reason for rolling element bearing failure is over lubrication. As the bearing turns, heat is generated and the grease needs room to expand. Too much grease in a closed environment like a wheel with a cavity between two bearings, which are also between a seal and a cap may generate excessive heat as the grease is "churned" by the moving elements. If it can't expand it may "cook" and harden and/or cause the seal to fail due to pressure build up. Seal failure can save the bearing but a mess ensues. My practice is to clean and repack the bearings every two years, clean and wipe the inside of the hub with grease to prevent corrosion and monitor the temperature of each wheel immediately at each stop. I also raise each side once a year, adjust brakes if needed and check each wheel for in/out slack and any grating noise when rotating the wheel.
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Old 04-06-2016, 02:03 PM   #17
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Originally Posted by Jacob D View Post
Industrial maintenance experience and articles by bearing manufacturers, lube manufacturers etc, have convinced me that a big reason for rolling element bearing failure is over lubrication. As the bearing turns, heat is generated and the grease needs room to expand. Too much grease in a closed environment like a wheel with a cavity between two bearings, which are also between a seal and a cap may generate excessive heat as the grease is "churned" by the moving elements. If it can't expand it may "cook" and harden and/or cause the seal to fail due to pressure build up. Seal failure can save the bearing but a mess ensues. My practice is to clean and repack the bearings every two years, clean and wipe the inside of the hub with grease to prevent corrosion and monitor the temperature of each wheel immediately at each stop. I also raise each side once a year, adjust brakes if needed and check each wheel for in/out slack and any grating noise when rotating the wheel.
Yeah, a few things here:
1) There is still a LOT of airspace in the hub when just a dam is used.
2) We're talking about a relatively low speed application...roughly 550 revs per mile...at 60 mph that's 550 RPM.

A healthy bearing and hub ( and one that is loaded below specs) doesn't get very warm under normal circumstances....unless you ride the brakes. If that's the case, you got bigger problems than how much grease you have in the hub, and any seal failure is due to the loose nut located 2 feet behind the steering wheel.
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Old 04-06-2016, 02:36 PM   #18
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Any grease located outside of the bearing cage will never find it's way into the cage. Grease is designed to stick to metal surfaces. So the grease in the cage stays there and the grease in the hub stays there.

The only time the grease in the cage would come out would be a petroleum based grease that has been in way too long and has lost it's modifiers & stabilizers. The grease then looses viscosity (thickness) and will run out where ever gravity pulls on it. Centrifical force may sling some back, however the point is the grease has been in service too long and should have been replaced.

If you ever get to look internally at a non-failed sealed bearing you may be surprised at how little grease is in there. These bearings are designed so zero foreign material gets inside and the grease inside is a synthetic.

Nearly every serviceable roller bearing failure is due to incorrect servicing because of -
Not a totally clean bearing - introduces debris which will damage bearing and/or seal
Incorrect seal installation causing distortion or damaged seal
Re-using seal causing distortion or damaged seal
Incorrect bearing installation which causes damage to cage
Incorrect pre-load - either too tight or too loose will cause excessive heat
Too much or too little grease - both will cause excessive heat

The last one is owner neglect not servicing bearings based on manufacturers intervals.

It is because of these factors automotive manufactures have gone to sealed wheel bearings in two wheel drive applications for the last 25 to 30 years. It takes a lot of grief off of vehicle ownership and reduces the required maintenance schedules.

This technology exists and can be easily applied to trailers that are not subject to water immersion. However the RV industry has been slow to adopt this and other "higher tech" solutions for running gear.

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Old 04-06-2016, 02:45 PM   #19
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I agree with Action;

My training was way before synthetics were around.....but some of the old petroleums would thin and run out of the rollers with no abuse and in less than the 15K maintenance interval.

Old habit die hard. Since synthetics, the grease stays put in the dams I build up. No slinging, no "churning" and not even flattening out across the inner hub surface due to small centrifugal forces.

Action is probably right that with synthetic grease the dams aren't necessary...but that's how I was trained....what can I say. But, like i said above, and Action iterates....I don't have to worry about it anymore, as all my "stuff" now has sealed bearing sets.
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Old 06-06-2016, 02:58 PM   #20
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Originally Posted by ROBERT CROSS View Post
Mine also.... We must have gone to different 'schools' together with the same instructor.

Bob
+3

Synthetic lubricants are not the "magic" elixirs some folks believe and repeat.
Synthetics were invented due to shortages of the "real thing" and just because the label states "synthetic" does not equate to "better" in all cases.

The usual advantage modern synthetics have are tenacious long-chain molecular structures which do not break down from shear and pressure as quickly as petroleum lubricants. But that does not mean they don't suffer from the same problems of contamination, heat, and mis-assembly.
So if you don't plan to regularly inspect/repack your bearings such as is annually recommended, then synthetic grease is a good thought. However regular mx will be served just fine with ordinary NLG#2 grease.

I believe Bruce was inquiring as regards the large empty space between the inner and outer bearings.... as opposed to some answers regarding the hub CAP... which is a dust-cover for the outer bearing.

The answers which mention light application of thin coating for purposes of rust-prevention are not wrong. That is a valid reason to lightly coat the hub cap...as well as the axle between the two bearings.
However some applications require more than a thin coating on the inner axle spaces, as the grease in the roller-cage-cone will liquefy at running temperatures and circulate among the rollers, and centrifugal force will sling it out of the cup unless cooler/thickened grease retains it within the bearing.

I was a rear-axle technician with Gulf States Toyota in the early '70s and I was taught to fill to 3/4's point the hub over the inner axle area and lightly coat the running-surface of the seal-landing-area of the axle, as well as all the axle and the inner surface of the hub-cap. We were also taught to lightly pre-load all cone bearings such that zero end-play existed. (as opposed to those that teach backing-off the bearing if the cotter does not match the locknut area.) The theory was taught that the cup and hub would expand if excess temps develop which would then adversely affect the rollers which would "chatter", and then air would whip the grease into froth (some call it "churning") which then deprives the rollers of cooling...and the ever-increasing damage occurs to the point of failure.

I've always repacked bearings as I've just described I was taught and I have never had any sort of failure.

But I've certainly repaired a number of bearing failures of others who did not subscribe to that technique.

It is indeed true that this is a subjective matter... OVER packing with grease can escape and ruin brakes... so certainly don't do that. But I add a generous amount of grease to the inner axle area as I've described.

(Think about this: if a generous amount of extra grease in the inner axle area is harmful.... then why don't "bearing buddies" and similar products fail regularly?)
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Old 06-06-2016, 04:00 PM   #21
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Quote:
Originally Posted by Boxite View Post
+3

It is indeed true that this is a subjective matter... OVER packing with grease can escape and ruin brakes... so certainly don't do that. But I add a generous amount of grease to the inner axle area as I've described.

(Think about this: if a generous amount of extra grease in the inner axle area is harmful.... then why don't "bearing buddies" and similar products fail regularly?)
In my opinion generous amounts of extra grease in a hub that never sees water isn't necessarily a harmful situation. Wasteful is a more accurate and messy. Harmful not necessarily unless it attracts foreign debris during the re-packing process.

4X4 trucks and boat trailers that the hubs can get dunked into water have extra grease in the hub because the hub can get rapidly cooled from the exposure to water. This creates a situation that water can be sucked into a hub because of contraction of the metal and grease. A properly installed "Bearing Buddy" allows for expansion and contraction of the grease in a sealed environment. With a dust cover the expansion and contraction of the grease occurs outside of the hub either through a vent hole in the cap or through the dust cover mating surface which is not air tight.

Travel trailers don't need that type of protection from water because they never see a water immersion situation.

The extra grease in a hub, doesn't harm nor is there any benefit, in my opinion. If there was a benefit (axle) manufactures would fill the hub of a sealed bearing with lots of grease. Even the few hubs that are serviceable are not filled by the original manufacturer at initial assembly.

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Old 06-25-2016, 11:40 AM   #22
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Just to add confusion to this subject (and also to cast dispersion upon my own former posting)....
...My Dexter Axle Manual provides instructions for repacking wheel bearings on their axles.
In summary, they recommend filling the bearing with grease (their method is the blob-in-the-palm-crammed-sideways-into-the-bearing-cone-method) with nothing mentioned about excess grease in the hubcap or axle-cavity.... BUT... they also specify to install the wheel/hub on the axle while tightening the spindle-nut to 50 lbs torque...THEN to back the nut off and re-tighten it HAND-tight WITHOUT spinning the wheel.... Finally to back the nut up to the first available cotter-pin hole. (THey also do not mention synthetic grease but only specify NLG #2)

I did my own per my own previous posting and have now run the trailer over 5K miles without any issues, but I thought Dexter's instructs should be posted for fairness and clarification.

Hope this helps.
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Old 06-27-2016, 02:33 PM   #23
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... they also specify to install the wheel/hub on the axle while tightening the spindle-nut to 50 lbs torque...THEN to back the nut off and re-tighten it HAND-tight WITHOUT spinning the wheel....
50 foot pounds or 50 inch pounds?

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Old 07-05-2016, 04:51 PM   #24
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Is there any justifiable reason to pack the center cavity full of grease when doing a repack and brake job.

Seems like a waste to me.
Just spent better part of day helping friend repair his missing wheel and hub on a tandem axle, #10k trailer.

From the looks of it, I'm guessing the outer bearing failed, and ground thru the stop washer... letting the whole wheel, and still lugged hub to freewheel off into a bean field somewhere. He had no idea how long he was riding on three-wheels.

He said it had been serviced (cleaned, replaced) about three years prior.
It's a Dexter with a zerk on the end of the spindle that he recently pumped copious amounts of grease into. The whole hub and dust cap was packed with grease.

I could see grease had escaped thru the inner bearing seal, and coated the magnet and shoes. Coincidentally, he mentioned very poor braking performance, of late.

The spindle where the outer race and bearing had ground down was scored, so I sanded it down, packed the new bearings full, lightly greased the whole spindle, cleaned all the surfaces and magnet (including magnet surface on hub) with lots of brake cleaner, then reassembled. Torquing the nut to 50 ft-lb, then backing off and finger tight.
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Old 07-05-2016, 06:07 PM   #25
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http://www.airforums.com/photos/show...iginal=1&c=508

Here's the spindle that lost wheel.

It was the other three assemblies that showed signs of heavy grease (in the hub) and contaminated surfaces.

Reason for failure? I'm guessing cheap bearing.
But, IMHO over-greasing causes problems.
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Old 07-06-2016, 04:28 AM   #26
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From the horses mouth.

http://www.timken.com/en-us/products...riveAxles.aspx
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Old 08-31-2016, 02:21 PM   #27
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OK fellows, I'm confused.

I purchased a 2015 23 FB in Jan of 2015. We used the unit 5 times in 2015, towing it about 1500 miles. Because of work, life, grandchildren and other stuff the wife and I did not use the trailer again until this last weekend. We had a terrible 4 days because the A/C took a dump. I towed the unit home and dropped it off at my AS dealer to get the A/C fixed and they tell me my wheel bearings need to be repacked, some type of refrigerator service needs to be done and an AS lubrication needs to be done to all the window seals, hinges, etc.

Now AS claims never lube axles.............why do we have to repack the bearings at less than 2000 miles on the trailer? The dealer wants $325.00 to repack the bearings.

What is a refrigerator service and an AS lubrication service?

I've owned many an RV and traveled many a thousand miles and never repacked the bearings, they all had Dexter Axles with grease fittings. A couple of pumps with the grease gun once a month while in use and I never had a failure.

Goodyear tires on the other hand.................
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Old 08-31-2016, 08:48 PM   #28
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2015 FC23FB - Have one too. The maintenance you reference is the annual service recommendation, well kind of.

Window seals need to be cleaned and dressed to keep them from sticking to window. You should do this on a regular basis. No reason the dealer should need to do it unless you can't change a light bulb.

The 23 does not have never lube axles. Believe the 25 and bigger do. However, unless the Virginia weather is considerably humid and the grease absorbs a lot of water, a repack probably is not required on an annual basis. Our dealer told me no. I kept asking and when it was time to check the brake status at 23K he said go for it. It is a lot dryer in California. You folks have Hurricanes. So, have a face to face conversation with the service manager to get the full story. Developing a good relationship with your dealer service department folks is in your best interest.

The refrigerator service is a cleaning of the coils and seals, as well as a check of the propane refrigeration circuit. Not been recommended by our dealer. They do offer it.

Will be interesting to hear what you decide and how it works out. FYI - There are a few more miles on the trailer than what you have rolled. Trailers are often delivered from factory to dealer on their own wheels.

Good luck with your research. Pat
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