Replacing the Bearing, Races and Seals on a Trailer Hub
No parts are more critical for the dependable performance of your trailer than the bearings, races, and seals. To ensure that your trailer performs reliably, you should inspect the
bearings, races, and seals and repack the bearings every 12 months or 12,000 miles.
After the grease cap on the spindle is removed, the castle nut should be visible. The castle nut holds the hub and bearings in place.
You will then see one of three devices that lock the nut onto the spindle. The most common is a cotter pin. Just bend it straight and pull it out.
Then you may see what is called a "tang washer."
Wipe the extra grease off the nut and look for a "tab" that is in one of the notches of the castle nut.
With your screwdriver, push the tab back toward the spindle. Spindles with a flat spot on the threads are a dead giveaway that the spindle will use the tang washer.
(These EZ lube spindles are "D-shaped" at the end and have a zerk fitting to transport grease to the bearing location.)
Finally, you may see a type of "cage" surrounding the nut. This is also on an EZ lube spindle and will just snap off the nut.
Use your screwdriver to gently pry off the cage in a circular motion around the nut.
Remove the Hub:
If the hub is in good condition, it should slide right off the spindle.
Use a paper towel to hold in the outer bearing as you pull off the hub.
If the hub is stuck, rock it in a circular motion to help slide it off.
If that does not work, use a mallet to tap the back side of the hub in a few places.
If the bearing is frozen to the spindle, you will have to knock off the hub with some force.
When this happens, often the hub will come off but the bearing and seal will stay on the spindle.
In this case you will have to work off the frozen bearing by using a chisel to break it loose.
If you chisel the bearing, be very careful not to hit the surface of the spindle, especially where the seal rides.
Even the smallest of nicks can wear out the bearings and seals very quickly.
If there are any nicks in the spindle where the bearings or seal sit, then you will want to replace the spindle or the entire trailer axle.
If you run into a frozen bearing you may want to consider taking the axle to a local garage.
Disassemble the Hub
Remove Outer Bearing:
Pull out the outer bearing and spindle washer.
The outer bearing is closest to the outside of the hub.
It is the one that hit the ground if you did not catch it when you were pulling off the hub.
Set the bearing aside.
Remove Inner Bearing and Seal:
Now you will need to remove the inner bearing and seal. (With luck it was not stuck on the spindle).
Place the hub, with the wheel studs facing up on a hollow cinder block or on a couple of 2x4s.
Then use a 1" wood dowel rod or scrap lumber that will fit into the center of the hub.
Place the dowel rod against the inner bearing and knock out the bearing with the mallet.
Do this in a circular motion.
The reason for wood is that it will transmit the force of the hammer but will not nick the bearing or race.
The grease seal will be pushed out by the bearing.
If you are planning on replacing the seals, another option to remove the inner bearing is to simply punch a hole in the seal and pry it out with a flathead screwdriver.
Be careful not to damage the hub and race when prying.
Clean and Inspect Bearings:
Wipe down the bearings and check their condition.
Look for nicks in the roller and dents in the roller cage.
If you see any of these problems or if you see lines, spots, or discoloration of the metal, discard the bearings.
If everything passes inspection, clean out the bearings and allow them to dry.
The best way to clean out the bearings is by using a heavy-duty degreaser and a paper towel.
Make sure to wipe down the bearing after it has been cleaned.
In a pinch, you can use a low-suds dish detergent such as Dawn to help cut through the grease.
If the bearings have to be replaced, look for the number stamped on the ends or side of the bearing.
If the hub slid right off you should be in good shape, but you will still want to double-check the area where the bearing and the seal sit on the spindle.
Again, use the fingernail test. Simply run a fingernail across the spindle; if it catches, you will want to replace the spindle.
Spend some extra time on the spindle where the seal rides.
The smallest nick will wear out the seal very quickly.
If there is a sizable nick or gouge, you may need to install a new spindle.
Be careful when using bearing protectors not to overfill the hub with grease because too much grease can blow out through the grease seal. This can be especially messy on drums with brakes.
Repack the Trailer Bearings
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 use a bearing packer, 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 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.
The dust cap will install directly over the castle nut. You should be able to start installation of the dust cap with your hands by pressing it into the center of the hub. After it has been started, use a piece of wood to tap it in the rest of the way. Make sure the outer lip on the dust cap is tight against the hub or drum. The wood will help you to avoid damaging the dust cap.
The main purpose of bearing protectors is to keep out water. A grease-filled hub will have some pressure built up inside, and this is what prevents water from seeping in. When filling the bearing protectors with grease, be careful not to overfill them. To help prevent overfilling, the bearing protector will have a small hole that allows the excess grease to spill out the side.
It is not a good idea to fill the hub with grease on every trip. If the release valve is clogged, or the hub runs out of room, the grease will probably blow out through the grease seal. If you have brakes on the trailer and the seal fails, the brake shoes will be contaminated and will need to be replaced.
It is good practice to fill the hub until grease starts to move the pressure spring on the bearing protector. Check it to see whether the spring has gone down then add a little more. Bearing protectors come with bras (or covers) that are designed to keep the excess grease from flinging out of the release valve and help to keep your wheel clean.
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