Bearing Buddy Question

Good Day!
I have a boat trailer to which recently I rebuilt the hubs and added bearing buddies. What confounds me is that there’s a huge cavity between the two bearings inside the hub. Now once you charge the buddy with grease that forces it against the outside of the outer bearing,and the grease will work it’s way through the small slot into the bearing to keep it happy. Now what about the inner bearing? There’s just a huge cavity of air in there, any grease that makes it’s way into the cavity from the buddy will have no purpose. I’ve watched a bunch of You-Tubes regarding hub rebuilding and nobody packed their hubs solid with grease.
If the buddy only benefits the outer bearing then it’s kind of useless? You would still have to pack the inner one manually either way!
Appreciate any feedback, thanks

When doing the bearings you also put grease in the hub.I pack the bearings every year on my boat trailer.I’m not a believer in BB they don’t magically push water out and fresh grease in the bearings.I would pack some grease in there and this fall redo them before storage.

Greg Riemer wrote:

There’s just a huge cavity of air in there, any grease that makes it’s way into the cavity from the buddy will have no purpose.

The primary job of a bearing buddy is to keep out moisture intrusion.
That cavity of air will expand and contract during normal operation. The bearing buddy maintains positive pressure. During times of contraction, this positive pressure will feed a small amount of grease into the hub, to offset the air contraction,,,,,,,, rather than having moisture sucked into the hub.

I have had Bearing Buddies on my trailer since I bought it in 2010. I do 5-6 trips from metro MN to the I-Falls area yearly plus many more short trips to local lakes. Never a bearing failure.
As with everything mechanical, you need to be aware of the maintenance needs. You can’t just fill the BB’s once and forget them. Check the springs regularly and keep enough grease in them to maintain spring pressure and you will never need to disassemble and repack bearings. Read the manufacturer’s instructions.
On long trips, at every rest stop I check tire temp and hub temp with my hand. It’s never been a problem, but it only take seconds.

Ron wrote:

I have had Bearing Buddies on my trailer since I bought it in 2010. I do 5-6 trips from metro MN to the I-Falls area yearly plus many more short trips to local lakes. Never a bearing failure.
As with everything mechanical, you need to be aware of the maintenance needs. You can’t just fill the BB’s once and forget them. Check the springs regularly and keep enough grease in them to maintain spring pressure and you will never need to disassemble and repack bearings. Read the manufacturer’s instructions.
On long trips, at every rest stop I check tire temp and hub temp with my hand. It’s never been a problem, but it only take seconds.

I have experienced the same.

We have had bearing buddies on three boat trailers in the past going back 35 years. Never a problem with bearings. Like already said, maintenance and periodic checks go a long way to keeping your hubs and bearing happy.

I’m really big on preventative maintenance. Maybe it is the mechanic in me as I really enjoy working on equipment.

I finally got sick of BB’s too. I switched to Liqui-Lube. They cost about the same and last a long time. I felt guilty after 5 years of not charging bearings, you can them with LL, and took them off. The bearings still looked great. I changed them anyway but I’m sold on LL. With both make sure you get the good inner seals.

I havent had a issue with my bearing buddies on 2 boat trailers, and a sled trailer. Both over 10 years old with lots of miles. Just keep them filled and you are good. I haven’t had one go bad yet. ( knock on wood)

Most people over fill there Bearing Buddies you only want to put in enough grease to see the spring compress, and that`s it otherwise you will get grease leaking out of the inside seal. I should not say this but my trailer is 22 years old have only pulled and packed the bearings twice in all that time due to keeping my Bearing Buddies at there proper tension.

I like bearing buddies but two of my trailers have a better system that comes standard where grease is channeled from the inside out.

Huntindave wrote:

The primary job of a bearing buddy is to keep out moisture intrusion.
That cavity of air will expand and contract during normal operation. The bearing buddy maintains positive pressure. During times of contraction, this positive pressure will feed a small amount of grease into the hub, to offset the air contraction,,,,,,,, rather than having moisture sucked into the hub.

This ^^^^. There is a huge misunderstanding out there as to what Bearing Buddies do and how they do it. Lubrication and pushing grease into the bearing is NOT the point, the point is to keep positive pressure inside the hub to help stop water and grit from entering the hub. This has been misunderstood ever since Bearing Buddies came out.

The enemy of boat trailer bearings is NOT lack of lubrication. Utility trailers can run tens of thousands of miles without adding grease. Grease ina sealed hub will stay good practically forever.

Boat trailer bearings die because of the grit and water that gets into the hub when the trailer is backed into the water. The water causes rust and the grit causes friction wear. That’s what kills trailer bearings. Once rust and pitting starts, NO AMOUNT of grease-adding will save the bearing.

3rdtryguy wrote:

I switched to Liqui-Lube. They cost about the same and last a long time. I felt guilty after 5 years of not charging bearings, you can them with LL, and took them off. The bearings still looked great. I changed them anyway but I’m sold on LL. With both make sure you get the good inner seals.

Oil bath hubs have a different set of pros and cons, but the enemy is the same. Grit and moisture. Guys want to equate oil bath boat trailer bearings with semi-truck trailer bearings and how long they last. But when’s the last time you saw a truck driver back his semi-trailer deck-deep into a lake?

Oil bath hubs provide great bearing lubrication, but if grit and moisture get in, there is the same potential for issues with corrosion starting to eat the bearings. Also, when a conventional grease-filled bearing setup has an inner seal go bad, the result is just more water gets in and potentially more grease gets out. Seals going out on an oil-bath hub system means catastrophic bearing failure within a few miles.

Not saying oil bath rigs are good or bad, they are different and have different and more constant maintenance requirements to check for moisture incursion and seals starting to fail. From what I’ve seen of the way the average guy maintains his boat trailer…well…on average guys are better off staying old school.

They all work if you take care of them.

Take them for a ride and warm them up then top off the grease. You fill that middle cavity then. The grease gets warm and moves around.

I pull my hubs and manually grease and inspect every fall needed or not,
never been left on the road knock on wood I can do the 20 minutes per side inner and outer

It took me to many years to figure bb out. Always packed to much grease blew seals out etc. finally with help from here my new trailer with bb has been awesome no water ever in them. Pull off and check everything in the fall for sure mid summer usually pull off just to make sure everything is happy. While turning the wheel add grease until the spring starts to move then STOP! Absolutely love them now. As Scratcher said A quick pull off double check it’s less than 20 minutes and goes awesome now I don’t dread it so much.