There's a very good bearing repack document available for downloading at the Dexter axle
site, including specific grease recommendations.
Here's a file from the Scamp
Date: Fri Mar 21, 2003 3:11 pm
Subject: Re: [scampers] greasing wheel bearings
Here's my two cents worth on the subject, having been forced into becoming an instant expert after having a rear grease seal fail in Annapolis last fall
Greasing the bearings or "packing the bearings" as most call it is NOT rocket science, but there IS a right way.
Jack up the side of the trailer you are about to work on (tip: loosen the lugs nuts on the wheel BEFORE you jack it up so you'll have the friction of the tire against the ground to hold the wheel steady while you loosen the nuts).
Set all lugs nuts someplace where they wonít roll into the grass and become history - ask me how I know about this!!
Pry the "dust cover" off from the center of the hub and set it with the lug nuts. Under the dust cover you are going to see a big, greasy, nasty looking nut with a cotter pin thru it and the shaft, with the end of the cotter pin bent back on its self to keep it there (another tip: use a new cotter pin when you are through. You CAN use the old one if it hasn't been reused so many times it's about to break from all the bending).
Bend the cotter pin back out straight so you can pull it out with a pair of pliers. Set it off to the side
with the lug nuts and the dust cover.
Get a big socket that will fit the nut. This is called the "castle nut", Ďcuz it sort of looks like a castle, with all the ups and downs (ramparts) all the way around it. Loosen the castle nut and take it right off the threaded axle
shaft, set it with the other stuff you have in safekeeping.
NOW, you can grab the wheel hub and slide it right off the shaft.
DON'T just set it down in the dirt...lay it on an old piece of cardboard or a towel to keep from getting sand in your bearings and inside the bearing "races".
The front and rear bearings are identical (at least on a Dexter hub like the one on my 13 footer - not sure about the rest. At any rate.........
The outside bearing will be loose now and you can just take it right out of the center of the hub. Set it down on the cardboard or towel. The rear bearing is being held captive by something called a grease seal. Just like it sounds, its job is to keep the grease inside the hub and not sling out under centrifugal force at highway speeds. Again, ask me how I know this !!
The grease seal is tapped into its "groove" with a friction fit. If you are REAL careful, you can pry it out and be able to reuse it, but I'd already have new ones ready to go that you bought that morning at the NAPA store. Ask Scamp
for the NAPA number or take your old one into NAPA and they will "mike"
it and sell you the correct replacement.
NOW you're ready to go.
While you were at the NAPA store, you bought some "bearing grease", they will know what you want. It will most likely be called "white lithium" grease, or just plain ol' "bearing grease". It's good stuff and holds up under the high temps of highway driving. Here's whatcha do:
First, inspect both old bearings for signs of wear or failure. You will see that the bearings are what they call "roller bearings" - they have a bunch of little round bearing surfaces all the way around a tapered
body like little miniature rolling pins. Play with them between your fingers and make sure each is free to rotate in its "race" without ANY binding or restriction. Also check to see that they are ROUND not flat on any surface. If you suspect ANYTHING wrong, go back to the NAPA store.
It's cheap insurance to just replace them!!!
If you like the old bearings and they rotate freely and look good, proceed to "pack" them:
Clean off the old bearing, making sure things like dirt, sand, whatever are all removed from them. If you have access to an air compressor and can blow them out, I'd do that too.
Put a big ol' glob of your bearing grease in the palm of your hand (your hands already look like you fix transmissions for a living anyway.......don't worry about it ! ).
Now, with the other hand, kind of smush the bearing into the blob of grease while at the same time you kind of drag it across your palm. What you are trying to do here is FORCE the grease into the bearing, not just ON to the bearing - you are "packing" the grease INTO the bearing.
A properly packed bearing will have grease in between all the rollers, in the races, everywhere grease can go. Anything less and you haven't PACKED the bearing - you just put grease ON it. Do this over and over until the grease you are packing into the bearing on one side is pushing grease back out the other side. In other words, a full exchange of grease. Only then are you done.
Repeat for the other bearing.
Drop the rear bearing in its bearing "race" and make sure you have the taper of the bearing and the tapered bearing race in the proper alignment. Take your grease seal and set it in it's groove, rubber ring UP, and tap it gently in place until it seats and won't go any further. Try not to get it crooked, just nice and flush.
Wipe the axle
shaft off nice and clean with an old (clean) rag, including the "shoulder" of the shaft -the bigger part towards the inside of the shaft, where the seal is going to ride.
Drop the outside bearing in the outside race on the front of the hub and then slide the hub onto the shaft. If you don't hold onto the outside bearing, the shaft will knock it back out and it will fall
in the sand!
Hold it with your fingers, or wait until the hub is on the shaft and THEN put it in place.
What you have now is a hub with two nicely packed bearings in both the back and the front. But now we have to secure the hub back on the shaft with the big castle nut and the cotter pin.
Here's what you do:
Hand-tighten the nut onto the shaft, with the castle "points" toward the outside. Continue tightening the nut BY HAND until you just canít tighten it any further. So far you haven't used a wrench. Grab the hub in both hands and push/pull it back and forth checking to see how much, if any, "play" you have on the shaft.
You want nearly none.
Now rotate the hub on the shaft. It should spin freely and not bind. Take a look at the side of the castle nut and see if any one of the slots in the nut have lined up with the hole (drilled horizontally) in the shaft. If one IS aligned, you're lucky. Slip the cotter pin through the nut, through the shaft, out the other side of the nut and bend the end of the cotter pin back over. You're almost done!!
If a slot in the castle nut and the hole in the shaft are NOT aligned, you have to turn the nut some more until it is. This is a judgment call, and source of all kinds of arguments between mechanics. Some will tell you to BACK OFF on the nut until the very first time you see a slot align with the hole in the shaft, and pin that. Others will tell you to take a wrench and TIGHTEN the nut until the first time you see a slot align with the hole in the shaft. If tightening the nut lets you slip the cotter pin back through AND the hub still has no binding - you're OK and you can cotter pin it like that.
BUT, if tightening it creates binding when you try to spin the hub on the shaft, BACK OFF on the castle nut until you can pin it. Use common sense here though: If backing off on the nut allows you to slip a cotter pin thru but you have lots of play between the hub and the shaft, that's not good either.
Go back and tighten it.
Do the other side the same way. Before putting the dust covers back on, put a big old glob of grease on top of the castle nut. Conventional wisdom says the grease will go along for the ride until the next time you pack your bearings and centrifugal force will kind of sling it around against the outside bearing. I even put a handful of grease INSIDE the hub between the two bearings BEFORE I put it back on the shaft, so it will help to grease the back bearing as I bop down the road.
Set the tire and rim over the hub, align the lug nut shafts with the holes in the rim, put your lug nuts back on - make sure the tire, rim, hub assembly spin nicely, and lower the jack.
You should be ready for a new season.
Side bar: The folks at Scamp
tell me they like to "pre load" the torque on new bearings. Here's what they mean:
If you used NEW bearings, they have never been under load yet. When you snug up your castle nut, use a wrench this time and kind of snug the nut until there is just a bit of binding on the hub when you try to spin it on the shaft. Then, back off on the nut and follow the above instructions. This way, you sort of compress the new bearings into their races, as they will do anyway under normal highway stresses.
Hope this way too long missive helps you newbies. Feel free to contact me privately if you need further advice.
OK.......now the rest of you guys can counter everything I just said.........I'll sit back and read the other tips.
Brian in Mich