Pack the Bearings:
The next step is to pack the bearings with grease.
You need to fill every space of the bearing with grease.
You can get a bearing packer from your local auto parts store, or the bearings can be repacked by hand.
If you are going to do it by hand, start with a gob of grease in your palm and then press the trailer bearing into the grease with some force.
Do this one section at a time and overlap the sections. Start on the front and then move to the back side of the bearing.

Insert Inner Bearing and Seal:
Turn the hub over so that the front side with the wheel studs faces down on the table.
Place the inner bearing in the hub and install the seal on top.
Tap the seal in a circular motion until it sits flush.
Next, apply a thin layer of grease to the spindles.
Then slide on the hub.
Be sure the seal is set in the proper position on the spindle.

Insert Outer Bearing and Seal:
With the hub already on the spindle, you can now install the outer bearing.
Slide it in while rocking the hub back and forth until the bearing is seated into the race.

Install Washer and Nut:
Next, install the spindle washer and tang washer (if necessary).
Then install the castle nut.
Tighten the nut until it stops or becomes snug.
Rock the hub and push in to make sure the hub is fully seated onto the spindle.
Then tighten the castle nut a little more.

Final Castle Nut Adjustment:
To make sure the hub is seated properly, back off the castle nut until it is loose.
Then tighten the castle nut snugly until it stops.
Look to see where the cotter pin hole lines up with one of the notches on the nut.
On hubs that use the tang washer or cage to lock the nut, you will have to do this by sight.
Then back the nut off one notch, so that the cotter pin will fit through the castle nut.
Install the cotter pin and then spin and rock the hub.
When you rock the hub you should feel the hub barely moving front to back.
Try experimenting by loosening the castle nut one more notch to feel the difference in the play in the hub.
Then install the wheel and rock the hub again.
On the outside edge of the tire, the movement should not be more than 1/4" inch.
Any play should be barely noticeable.
When you are satisfied with the adjustment, secure the cotter pin.
Push the pin through the hole on the end of the spindle and through the notches on the nut.
Then split the bottom of the pin to the left and right.then repack bearings finished.