bearing packing question

[f4rioboy]

Hi all,
I will be repacking my trailer bearings with Bearing Buddies for the first time this weekend. As I mentally go throught the process, I have a question.

a. How much grease do you put in the space between the inner and out bearings? Do you lightly coat the spindle with grease or do you pack as much in there as possible?

Thanks.

 

[RiverRat]

It really doesn't matter how much grease you put in this space because... Once you re-assemble the axle you will still pump up the bearing buddies with grease so just by doing this it will fill the cavity between the bearings.

 

[f4rioboy]

A couple more questions.

a. OK, so let say you hook up your grease pump to the Bearing Buddy and start pumping in new grease. How do you know that you have enought grease in there? What is the indicator for you to stop pumping grease?

b. I was told that one should put in one or two pump of grease before each trip out. Lets say that in step "a" above you have fill the cavity with grease. Wouldn't the new grease pumped in before each trip blow out the seal? When do you now not to pump anymore grease in there?

Thanks for helping a trailer newbie.

 

[Dave M.]

I believe the Bearing Buddy has a spring loaded pressure relief valve. As you pump grease into the bearing, the pressure will build until the valve opens and either air or grease is released. This puts positive pressure inside the hub, to help keep the water out. It won't move past the seal as long as there is pressure inside.

I don't have a clue about how long the pressure will stay inside the bearing hub. But suppose I were to take off with my Bearing Buddy equipped trailer in tow on a 100 degree day, drive for 20 miles at highway speed and cause the bearings to warm a bit. The air in there is fairly warm by now, and maybe it has heated and expanded a bit, and released a bit of air. Now I back down into some nice cool river water and cool the whole thing down under water. Hopefully the grease/air won't contract so much that it creates a negative pressure inside the hub and so that water is sucked in.

I would not take any wagers either way. But it seems to be a prudent idea to give it a bit of grease each time as you mention to restore any pressure that may have been lost on the previous outing. I also think you would need a volume of air in there to compress to maintain pressure as things heat and cool. Once the air is gone, you are trying to compress grease and have it maintain positive pressure. Liquids are not known for being very compressible. And from what I read, maintaining this positive pressure inside the hub to keep water out is the whole idea behind the Bearing Buddy system.

 

[Sundancer]

The Bearing Buddies have a floating zerk held in place by a spring. If you put too much grease in, the spring allows the zerk to move outward where it will hit a hole in the hub that will allow the grease to squirt out. It keeps you from over filling. Usually you put in just enough grease that the spring carries some of the load, but doesn't move out far enough to let grease out the hole in the hub.

 

[f4rioboy]

Thank you for the information. I now can confidently repack my bearings now.

 

[KC WV]

As far as frequency on re-greasing-more often is better. As you get used to seeing how many pumps it takes to make the spring actuate, you'll get a feeling for how often to add.

 

[Weave]

Try to refrain from over pumping since you can blow out the back seals and end up re-packing again.

 

[TRLR2dH2O]

a/ When repacking you bearings, put in as much grease as possible to start, to eliminate air pockets,then less pumps you will need

b/ You pump up the buddy, till the loops of the springs come together << some buddies have a relief hole in the side of the cap BUT NOT The STAINLESS ones and you can easily over pressurize them

c/ The BB is only designed to pumped till full, to create 3 lbs of grease pressure inside the hub, not AIR pressure
Then every year or two take apart, clean & check, add new seals

d/ what happens to frequently, is if you keep taking the gun to it, you over pressurize, causing the seal surface to open up then spewing grease out [possibly onto brakes] or possibly popping the BB off

e/ always recommended NOT to reuse BB's over as the mating surface is knurled and the don't fit as tight the next time
Dick