Repacking wheel bearings on boat trailers is a regular maintenance project. Overlook this task and you will be stranded beside the road when your wheel falls off! It is not hard to repack the bearings on a small trailer with no brakes, as you don't need to back off the shoes or bleed the caliper.
I prefer to do it with the trailer attached to the truck, as it's less likely to fall off the jack. Be careful jacking up the trailer, and don't get under it.
The top video is for dialup users, the large one below for broadband.
You do not need to remove the wheel from the hub unless the hub is ruined and requires replacement. Remove dust cap. I used to have a pair of "channel lock" pliers that were quite good at removing dustcaps, but I've lost them, so now I use a chisel, screwdriver or something else that's not too sharp to start the cap moving. If you go too far you'll cut through the cap, so just get it loose as shown.
Straighten and remove the cotter pin, which is what holds the nut in position. I use a pair of needlenose pliers or sidecutters for this.
Unscrew the nut. If the axle and nut threads have not been messed up you should not need a wrench to turn the nut. Sometimes spinning the wheel helps move the nut. Never use a wrench to tighten this nut!
Wiggle the wheel to make the outer wheel bearing move out enough for you to grab it and pull it off. Have a clean rag or paper towel to put it on so you don't get dirt in the bearing.
Pull wheel and hub assembly straight off the axle. If you want to reuse the grease seal (which I do not recommend) be careful to support the weight of the wheel so the end of the axle does not ruin the rubber part of the grease seal.
To remove the inner bearing you must remove the grease seal. Place the wheel and hub on the floor inner side down, so that the center of the hub is not on the floor and the grease seal has room to fall out. Use a suitable long punch to tap on the inner bearing as shown to drive the grease seal out. I use my long socket extension for this.
Remove inner bearing. Clean both bearings, which should be covered and impregnated with dirty grease. If you wipe off as much of the grease off with paper towels before you use solvent it takes very little solvent to get them clean. Inspect the rollers for any pits or scars, if you see any at all go buy new bearings, which come with new outer races. Take the clean old bearings and seals with you, so the parts place can match them. I really don't like to reuse the seals, as they help to keep the water out when you launch your boat.
Clean all the old grease, dirt and water from the inside of the hub. Sometimes there is a lot of grease in there, so I spoon it out first, then wipe the remainder out with rags or paper towels. Clean the axle off too, and remember to clean the surface where the new grease seal will ride. Carefully inspect the "races" inside the hub for pits or scars, it should be silky smooth. If not, you need new bearing and races.
Repack the bearings with new grease. Basically, you put a little grease on your palm and mash or roll the bearing into it until it's gone into the bearing. Put more on your palm and repeat until you can no longer get the grease to go from your palm into the bearing.
Turn the wheel inner side up and place the inner bearing in the hub, then drive the new grease seal into the hub. This is so much easier with a block of wood. The grease seal can sometimes be tapped in with a hammer, but it is too easy to dent the seal and ruin it. The rubber part of the seal goes on the hub side.
Put a little grease on the axle, but only where the grease seal rides. The axle itself needs no grease except to prevent rust, and normal use will take care of that. With caution, place the wheel on the axle so that you don't scrape the grease seal with the threads on the end of the axle.
Put the outer bearing over the axle and into the hub, replace washer if your trailer has one, and then screw the nut on finger tight only!. Wiggle the wheel, hold it straight by pushing on the top, and tighten the nut. Often it helps to turn the wheel while turning the nut. Do not use a wrench unless you have to because of bad threads! The nut is also the adjustment for bearing play, it must not be too tight! As the bearings warm going down the highway they expand, if the nut is too tight they have no room to expand and will dissintegrate, or fall apart. Continue to wiggle and turn the wheel as you tighten the nut until you feel no play in the wheel, then you know you have it
too tight! On most axles, back the nut off from the point where the play disappears 1/8 to 1/6 of a turn. This will position the bearings properly in their races with just enough room to expand when warm. You should be able to wiggle the wheel just a little bit. Spin the wheel and check again. Find a hole for the cotter pin and put it in. Spin the wheel again and wiggle to check the play. Bend the cotter pin over so it will not rub on the dust cap.
Replace dust cap. You should be able to tap it in if you're careful to keep it straight. A few I've had to use a square punch on the ring.
This video was taken with the Panasonic PV-GS35
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A word about "buddy bearing". Buddy bearings are just a special dust cap with a grease fitting. With them you can use a normal grease gun to completely fill your wheel hubs with grease. While many people like them, I think you should look at their advantages and disadvantages before you spend the money.
"Theoretically", having your hubs full of grease will keep the water out and your bearings will always be well greased and last a long time. You don't need to remove the hub from the axle to grease the bearings, just plug on your grease gun and give it some grease occasionally.
You use a LOT more grease. It doesn't take much to fill a bearing, to fill the entire hub with grease can take 50 times as much as just greasing the bearings. When eventually you do take the wheel hub off, you will have a LOT of grease to dispose of.
If you pump too hard you can blow the grease seal and not realise it, letting dirt and water in the hub anyway.
Pumping more grease into the hub may or may not sufficiently grease the bearings. It may or probably not expel all the water that has worked its way into the hub.
Sooner or later the wheel bearings will wear out anyway. Grease seals do not last forever, you will get water in the hub eventually, rust forms and bearings fail. If you don't take the bearings out and inspect them regularly, they will eventually fail, usually while you are speeding merrily down the highway. So even with buddy bearings you still need to take them apart now and then for inspection.
I think the "buddy bearings" are a good idea, but I don't use them. Just a matter of choice.
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