If you own a utility trailer, boat trailer, horse trailer, or other one- or two-axle trailer, then you will need to occasionally clean and lubricate the wheel hubs. Over time, these hubs become full of dirt and debris, plus friction-generated heat causes the lubricants to break down and become less effective. This job isn't difficult for a person handy with basic tools and can be accomplished in an hour or so. Below is a step-by-step guide to disassembling, lubricating, and reassembling a trailer wheel hub.
1. Remove the wheel from the trailer - Use a jack to elevate the trailer and remove the wheel as you would normally in case of a flat or when mounting a new tire.
2. Take the dust cap off the hub - Once you remove the wheel, the hub will be in full view. Before you can remove the hub, however, you will need to take the dust cap off the hub first. Slip a flat-edge screwdriver blade between the dust cap and hub and carefully pry the cap free. If the dust cap is stubborn, use a rubber mallet to tap the dust cap and loosen it.
3. Remove the nut and washer - After the dust cap is removed, use a pair of pliers to pull the cotter pin from the wheel nut. Next, loosen the nut with an adjustable wrench and remove it from the spindle. The washer behind the nut should also be removed and set aside.
4. Slide the hub from the spindle - At this point, the hub should be easily pulled from the spindle; be careful not to dislodge the bearings and loose any parts during this step.
5. Remove the hub's internal components - Inside the hub, there are several components that will need to be removed in order to clean and lubricate them. First, pull the outer bearing and cup from the wheel-side of the hub. Next, turn the hub over, and you will see the seal that protects the inner bearing by containing the grease. The seal can be removed by using a screwdriver to pry it from the inside of the hub. Finally, remove the inner bearing and its cup.
6. Clean all the hub components - Fill a flat container, such as an oil-collection pan, with about an inch of kerosene or another safe solvent; do not use gasoline due to the vapor-ignition risk. Next, place all the components removed from the wheel hub into the container and soak them in the solvent. Use a nylon brush to remove grease, dirt, or other debris from the metal, and then wipe the parts dry with a clean shop towel or rag. You can also use a heat gun or hair dryer to evaporate the remaining solvent from the bearings.
The interior of the wheel hub will also need to be cleaned. Thoroughly soak another clean cloth with the solvent and push it into the hub opening; take a broomstick or other sturdy piece of wood and ram the cloth through the interior of the hub. Repeat this a couple of times and look through the hub to check if it is clean. Continue to clean the interior of the hub until it is clear of debris.
7. Lubricate the bearings and components - Take a golf ball–sized portion of lithium grease and push it into the bearings, rotating the balls by hand. This will help evenly distribute the grease inside the bearings; be sure to fill in empty spots with grease before replacing the bearing cups. Next, apply a light coating of grease on the remainder of the metal surfaces, including the inside of the hub.
8. Reassemble the hub - After everything is well-lubricated, insert the inner bearing and cup into the wheel-side of the hub, then place the seal over the end of the hub. Use a rubber mallet to gently tap it into place.
Next, insert the outer bearing and cup into the opposite side of the hub, and then push the hub onto the spindle, being careful not to push out the bearings in the process. Slip the washer over the end of the spindle and thread the nut onto the spindle by hand. Then hen tighten the nut with an adjustable wrench. Follow up by slipping the cotter pin into the nut and bending the ends of the pin with a pair of pliers to keep the nut in position. Finally, slip the dust cap onto the end of the hub and tap the cap into position with the mallet.