Do I have to fill the entire hub w/ grease if using bearing buddy?

[salmonee]

I just went to bearing buddy's website and they say to fill the hub entirely w/ grease before installing bearing buddy. I didn't do this. I thought the idea of bearing buddy is so that you didn't have to fill the entire cavity prior to install? Do i have to take my tires out and redo all my work from this morning? Geezzzz.

 

[bruceb58]

Re: Do I have to fill the entire hub w/ grease if using bearing buddy?

You are supposed to fill the entire hub. What you can proabaly do is to fill it with the bearing buddy until the piston barely moves...drive the trailer or spin the whhel and continue doing this until the air all leaves the hub.

Did you properly pack the bearings with grease? I use one of those packing tools which makes life easier.

 

[bruceb58]

Re: Do I have to fill the entire hub w/ grease if using bearing buddy?

After thinking about this for a little bit, why don't you just take it off and do it right. I think I would.

 

[salmonee]

Re: Do I have to fill the entire hub w/ grease if using bearing buddy?

I did pack the bearing w/ grease and grease the races prior to install. I also add about 6-10 pumps of grease to the inner hub prior to putting it on the axle. I just didn't fill it to the rim.

 

[jackel440]

Re: Do I have to fill the entire hub w/ grease if using bearing buddy?

If the hub is not full of grease when you try to add grease through the bearing buddy there will be no grease to push through the bearing.It will just push grease into the cavity ,and never get to the other bearing until the cavity is full.So by the time that happens your inner bearing might be toast.Even though you thought it was good to go because you had been pumping grease into it.
Better pull it off and pack it full.Or take your chances.

 

[dingbat]

Re: Do I have to fill the entire hub w/ grease if using bearing buddy?

I did pack the bearing w/ grease and grease the races prior to install. I also add about 6-10 pumps of grease to the inner hub prior to putting it on the axle. I just didn't fill it to the rim.

You are not supposed to fill the inner hub with grease. If you backed your bearings sufficiently your 6-10 pumps is adequate for operation.

Run it and keep an eye on the bearing buddy. Probably need to add a pump for two of grease for the first couple of trips. Add just enough grease to keep the bearing buddy plate off the bottom. In this caae more isn't better.

Remember, grease is not a consumable in a "sealed" bearing hub. If you have to constantly keep adding grease find out why and remedy the problem.

 

[bruceb58]

Re: Do I have to fill the entire hub w/ grease if using bearing buddy?

You are not supposed to fill the inner hub with grease.

I totally disagree!

http://www.bearingbuddy.com/installation.html

"IMPORTANT: As you reassemble the components, fill the hubs completely with a high quality, multipurpose, no.2 grade lubricant (e.g., the type used for automotive suspensions). Don't use heavy, fibrous greases; don't mix grease types. "

 

[dingbat]

Re: Do I have to fill the entire hub w/ grease if using bearing buddy?

20 years as a machine designer, over 120 hours of PDH certified bearing design and maintenance courses and 30 years of practical experience tells me whoever wrote that installation sheet has a few things to learn yet

This was taken directly from the Timken bearing design manual.

It is important to use the proper amount of grease in the application.
In typical industrial applications, the voids in a roller bearing
should be filled from one-third to two-thirds with grease. Less
grease will result in the bearing being starved for lubrication. More
grease may create churning which generates additional heat.

As the grease temperature rises, its viscosity decreases and becomes
thinner. This can reduce the lubricating effect while increasing
leakage of the grease from the bearing. It may also cause
the grease components to separate, causing the grease to break
down. Also, as the bearing heats up, the grease will expand somewhat
and be purged from the bearing.

However, in low speed applications where temperature is not an
issue, the housing can be entirely filled with grease. This safeguards
against the entry of contaminants.

For best results, there should be ample space in the housing to
allow room for excess grease to be thrown from the bearing.
However, it is equally important that the grease be retained all
around the bearing. If a large void exists between the bearings,
grease closures should be used to prevent the grease from leaving
the bearing area.

During periods of non-operation, it is often wise to completely fill
the housings with grease to protect the bearing surfaces. Prior to
subsequent operation, the excess grease should be removed and
the proper level restored.

FWIW: I was taught, and have always used, a walnut size ball of grease in the inner housing. 30 years and I've not lost a bearing yet, knock on wood.

 

[bruceb58]

Re: Do I have to fill the entire hub w/ grease if using bearing buddy?

The whole idea is to have the hub under slight pressure so that no water can enter. An axle bearing would be considered a low speed bearing application and therefore satisfies the Timken recommendations.

If you really believed in not having the hub full of grease, why would there be any reason to have a bearing buddy?

 

[dingbat]

Re: Do I have to fill the entire hub w/ grease if using bearing buddy?

The whole idea is to have the hub under slight pressure so that no water can enter. An axle bearing would be considered a low speed bearing application and therefore satisfies the Timken recommendations.

The operating RPM of the bearing is calculated by multiplying the RPM x bearing diameter (in mm) x in this case, a service factor of 2.0 ? 2.5.

At 65 MPH a 14? tire is turning at 857 rpm. Multiply 857 x 50 mm = 42850 multiply that by 2, assuming 30% of the hub is filled with grease, and you get a design RPM of 85,700. Max is 250,00 so your right about in the middle of the range, again, assuming the housing only 30% full of grease.

Not screaming in bearing terms, but certainly not a low speed application given the load on the bearing. For a 12? tire you can double that number. That?s hummin right along here, even in bearing terms.

If you really believed in not having the hub full of grease, why would there be any reason to have a bearing buddy?

Once the hub is sealed the hub has a fixed volumetric area. For all intended purposes grease does not compress. You can not increase the pressure of grease by adding more grease.

On the other hand, you can compress air. Adding more air to a fixed area or decreasing the area with a fixed volume of air you increase the pressure. By adding a "volume" of grease you are in effect decreasing the volume thus pressurizing the hub.

Since air expands and contracts when heated or cooled, the volume of the air, and thus the pressure inside the hub, will increase and decrease with temperature. The ?seal? plate and spring in the BB is the pressure regulator. It?s designed to allow the air in the housing to expand and contract to maintain the pressure equal to or less than compression pressure of the spring in the bearing buddy.

From Timkem Wheeling bearing installation instruction

Lubricate
Pack cones fresh from carton. A
pressure grease packer is recommended.
To hand pack cones,
force grease under the cage
between the rollers from the
large end of the rollers until it
shows at the small end.
Fill the hub with grease to the
inside diameter of the outer races and also fill hub grease cap.
This layer combats moisture and retains grease in cones.
WARNING: Failure to correctly lubricate bearing and maintain
proper lubrication may result in damage that could cause
wheel to lock or come off during operation, creating a risk of
serious bodily harm.

 

[bruceb58]

Re: Do I have to fill the entire hub w/ grease if using bearing buddy?

Once the hub is sealed the hub has a fixed volumetric area. For all intended purposes grease does not compress. You can not increase the pressure of grease by adding more grease.

The whole idea of the Bearing Buddy system is for grease to have a slight positive pressure against the rear seals. If you don't fill the entire cavity and you dunk the hub into the water, the temp drops, a vaccum is created and water can be sucked into the hub. By using the bearing buddy, you don't have a fixed volume. By having the spring, the volume can change depending on pressure. Grease can and will expand as the hub warms albeit small.

I understand what Timken is explaining in their app note. I also realize that you have to weigh the marine problems in to the equation as well. There all always tradeoffs. This is just such an example.

 

[redone4x4]

Re: Do I have to fill the entire hub w/ grease if using bearing buddy?

The whole idea of the Bearing Buddy system is for grease to have a slight positive pressure against the rear seals. If you don't fill the entire cavity and you dunk the hub into the water, the temp drops, a vaccum is created and water can be sucked into the hub. By using the bearing buddy, you don't have a fixed volume. By having the spring, the volume can change depending on pressure. Grease can and will expand as the hub warms albeit small.

I understand what Timken is explaining in their app note. I also realize that you have to weigh the marine problems in to the equation as well. There all always tradeoffs. This is just such an example.

exactly. every square inch should have grease in it. I learned the hard way one year. when you put the hub on, pack inside around the axle with grease before installing the outer bearing, washer, nut, etc. to prevent any problems. thats how i do it, anyways.

 

[dingbat]

Re: Do I have to fill the entire hub w/ grease if using bearing buddy?

The whole idea of the Bearing Buddy system is for grease to have a slight positive pressure against the rear seals. If you don't fill the entire cavity and you dunk the hub into the water, the temp drops, a vaccum is created and water can be sucked into the hub.

So your argument is now down to you have to fill it with grease because it will suck air if the housing is pressurized with air.

Ok, lets look at that theory.

Air pressure rises linearly with temperature. Its very easy to calculate air pressure in a fixed volume at varying temperatures. So let put your vacuum argument to the test.

Atmospheric pressure is roughly 15 psi. If you add in the 3 psi positive pressure that bearing buddy claims we're at roughly 18 psi inside the hub.

Thermal expansion of air is roughly 0.3% per 1 degree C.

So lets say you filled the hub with grease when it was 20 degrees C outside. You drive down the road for a while and your bearings are just fine. They're running at a temperate of say 40 degrees C. So the pressure inside your hub is now 20 x 0.3 = 6%. So we add 6% (1.1 psi) to our 18 psi inside the hub at 20 degrees C and you're now up to 9.1 PSI.

So now you back your trailer into the water. The water is cold, it's only 15 degrees C. We neglect the fact that the thermal mass of the hub, grease, bearings, etc all play into the Delta T of the air inside the hub. Lets just assume that the air inside hub temps drops to 15 degrees C in a matter of lets say 180 seconds

So, -15 degrees C x 0.3 = -4.5% . So we take the 19.1 PSI and we subtract the 4.5% (0.85 psi) from the 19.1 PSI you end up with 18.2 PSI in the hub. We're still above the vacuum point since we're still above atmospheric pressure.

See where this is going?

The 3 psi is not an arbitrary number. It was used because the pressures swing inside the hub, at normal operating temps, is within that pressure range. This design would negate any vacum issues.

 

[Fl_Richard]

Re: Do I have to fill the entire hub w/ grease if using bearing buddy?

That sounds good but how does the equation change when you submerge the axles and now there is water pressure + atmospheric?

 

[salmonee]

Re: Do I have to fill the entire hub w/ grease if using bearing buddy?

Sorry for not updating this thread. I later realized I have one of those posi-lube axle which folks say is 20x better than a buddy bearing. It has a zirk fitting on the end and I can pump grease directly at the axle. The grease flows through some cavities in the axle to the back of the bearing and somehow when filled overflows to the front of the bearing. I can see grease oozing out the front after 40 pumps or so. It was pretty neat.

 

[redone4x4]

Re: Do I have to fill the entire hub w/ grease if using bearing buddy?

even better, cant go wrong with that setup.

 

[lmannyr]

Re: Do I have to fill the entire hub w/ grease if using bearing buddy?

Holy moly, dingbat is on a roll here. Guess I should add BB to my setup.

 

[dingbat]

Re: Do I have to fill the entire hub w/ grease if using bearing buddy?

That sounds good but how does the equation change when you submerge the axles and now there is water pressure + atmospheric?

It depends on if it?s freshwater or saltwater but it?s roughly atmospheric pressure plus.0.5 psi per foot of depth.

The hub would have to be 6 feet under water to equalize the "base" pressure inside the hub with a bearing buddy.

 

[stratos bandit]

Re: Do I have to fill the entire hub w/ grease if using bearing buddy?

Ok...for the first time, I just replaced both hubs on my trailer and installed new bears and seal.

I packed the bearings using the "palm method" and it was much easier & faster than I thought it would be.

As for filling the hub or not. I lubed both races up with grease and used a plastic spoon (long DQ spoon) and spread approx 2 spoonfuls of grease around inside the hub. I also have bearing buddies and once installed....put about 10 pumps of grease.

My question is.......is this enough grease or should I add more? Did pumping grease into the BB do any harm?

 

[redone4x4]

Re: Do I have to fill the entire hub w/ grease if using bearing buddy?

you want all grease, and no air in there. If you feel thats what you have, your good to go. Instead of spreading grease in there, i usually squirt it in with my grease gun before installing the outer bearings. As i am assembling everything, I want grease coming out towards me all the time. I can wipe off the excess, and then fill the remaining with the grease gun thru the bearing buddy. But, thats how i do it. im sure there are other methods that work as well.