This is the process I follow when I do the bearings on my boat. I learned this process a long time ago from two different guys, and both of them were pretty good mechanics.

1. Take wheels and tires off hub (Jack and jack stands, etc).

2. Pop the dust cap, and remove the cotter key from the castle nut. Loosen the castle nut (or a plain nut and a castle "flange" that goes over it). Pull the flat washer.

3. Pull the hub - in the process of doing this - the front (outer) bearing will come free - have a rag or your hand ready to catch it.

4. Take the hub to a workbench, and using a large screwdriver, pop out the grease seal, throw it away (well, save one so you get a matching one from the parts supply house of your choice). Then you can remove the rear (or inner) bearing. Where you get your parts depends on your trailer - mine uses stock/generic parts.

5. Wash out the bearings - parts solvent is good. I know you shouldn't do this but I use gasoline in a aluminum pie pan w/ a soft bristle paint brush. I also do this out in the open air - to allow the vapors to dissipate. You might need to change your cleaning fluid once or twice. This will get the dirt and old metal shavings out of them. (I then dump the dirt and gas in w/ used motor oil, and mix well - a neighbor has a furnace in his shop that burns used oil - the oil dilutes the small amount of gas - so that its safe).

6. Once the bearings are clean - dry them - I use rags. You should see no dirt anywhere - the race or the rollers/balls, etc.

7. Now I put a gob of grease on my finger tips, then push the grease into the cage, going all the way around the cage - this coats the outside of the bearings.

8. Now a big gob of grease going in to the palm of my hand, and holding the bearing vertically - I work the bearing across my hand, working the grease into the cage by rolling the bearing back and forth across my hand, so that grease is worked in to all the metal surfaces. Repeat for each bearing.

9. Clean out the hub. If you replace the bearings, you should replace the seats - drive them out of the hub w/ a pin punch / taper punch and a BFH (Big fat hammer). The new seats are installed by setting them in place (a little dab of grease on the surface will help them slide), the using a socket the same size as the seat (outside diameter), use a hammer to drive the seat in to the hub until it is in place. An extra set of hands to hold the hub is handy when doing this.

       If you are reusing bearings - just wipe them (hubs) out with clean rags. I just try to get the old "dirty" grease - clean grease I leave alone. Most of the time you can reuse your bearings - just make sure you keep straight which one is the inner, and which one is the outer.

10. Coat the seats w/ a layer of grease - do the inner (rear) first. Insert your bearing into the hub, then put more grease in it - a nice layer over it.

11. Do the seal next - again use a socket (the flat portion) and put it over the seal - tap it in place w/ a hammer until it goes in to place. The socket distributes the force of the hammer blows, so the seal doesn't get damaged. A block of wood would also work.

12. Do the outer (front) - coat the seat w/ grease, then slide the hub on to the spindle (clean it w/ a rag first), then put the outer bearing on, put the grease on, as you did w/ the inner bearing, followed by the washer, and the castle nut. Turn the nut tight, so the hub doesn't move. Then back the nut off about 1/2 to 3/4 turn, so the hub will turn, then maybe a bit more, just so you can re-install the cotter key. Then tap the dust cap in to place, or - if you have / bought Bearing Buddies, put them on.

        If you bought bearing buddies or a clone, put them on per the the instructions - I did mine using a hunk of 1x4 and a hammer (brand new ones will go on harder than ones that have been on before). Then fill the bearing buddy w/ grease - You squirt grease in until the seal on the bearing buddy (w/ the grease fitting) begins to float (rock on a cushion of grease). This could take quite a bit of grease.

Repeat for the other side.

    Then - when you roll the trailer down the road - check the seals on the buddies before you put it in the water. If they rock - they have plenty of grease. If they don't move, shoot in grease until they do. It does mean you have to take a grease gun w/you when you trailer the boat - but its that extra grease and "over pressure" condition which helps keep the water out. As long as you only put grease in the buddies up to the point they rock - you shouldn't blow out the grease seals or have grease leaks on the back side of the hub. Some grease might ooze out the front of the buddie, but it wipes off.

    I bought a used boat and trailer two years ago. Right after I bought it, I did the whole process - new seals, bearings, seats, etc, but skipped the bearing buddies. In the fall, before winter storage, I pulled the bearings again - and to my shock - had some water in the hubs, and some surface rust on the non-moving portions of the bearings. I repacked/cleaned the bearings and stored for the winter. Then last spring, I bought a set of Bearing Buddies - it was about $20, but they are worth it. Last fall - again prior to winter storage, I pulled and repacked the bearings - no water, no rust.

    One of the other posters commented about special seals when using them - my trailer doesn't use them, and according to the manufacturers literature, you won't blow (hub) grease seals if you don't over pressure the Bearing Buddie.