Read your RV user manual to determine when your bearings should be serviced. At the bare minimum, most RV manufacturers recommend an inspection and greasing at least every 10,000 miles, depending on what kinds of roads the trailer frequently travels. Smaller trailers require more frequent maintenance because smaller wheels spin faster, putting more stress on the axle.
Locate your trailer's service manual and find out how tightly the wheels need to be torqued. Also, locate the procedures that describe how to reassemble the wheels. Improperly tightened wheels will result in too much friction and create a hazardous situation.
Obtain a proper trailer jack, and block all tires on the opposite side with trailer chocks or wood blocks to ensure your safety while underneath the trailer.
Remove your wheel hub's outer seal to expose a castellated nut. A castellated nut has notches at the top of each of the nut's six sides, which makes it resemble the parapet of a castle. A hand-tightened tab keeps this nut in place. Firmly pull on the hub to remove the castellated nut.
Pull out the washer and outer bearings. Carefully keep all parts on a towel next to you, taking care to lay them out in a logical order of removal. Keep parts clean to avoid the risk of dirt adhering to the smooth, precisioned surface of your bearings.
Replace the wheel bearing's old grease with new high temperature wheel-bearing grease. This type of grease is different from chassis lubrication grease because it has a higher melting point that will work under hard braking temperatures. Greases such as lithium and bentone-based greases are ideal.
Pull out the brake drum, using care not to touch the brake with your greasy fingers. Then remove the wheel hub seal and dirty bearings. Clean them well but do not use solvent. Instead, try a thin film of lubricant. If bearings are pitted or damaged, replace with new ones.
Pack new grease into the hub with your fingers, using care to apply a fair amount around the sides while inserting a good reservoir of grease inside the hub itself.
Drop the inner bearing back into the hub. Then place the hub seal back inside, making sure that it's flush. Gently tap evenly around the seal with a light mallet, while using a hard piece of wood to spread the impact load and prevent damage to the seal. Lubricate the lip of the seal.
Reinsert the assembled hub. Next, put in the outer bearing, then the washer and finally the castellated tab. Apply high temperature grease on the castellated tab. Lay the castellated nut over the tab, then click in place. Use care not to overtighten. Finally, place the cap back on the hub.
Adjust the trailer wheel brake. A slot in the rear of the brake drum will provide access to a starwheel for adjusting the brake's friction. The starwheel won't be visible as its hidden inside the drum, but it looks like a small bicycle sprocket. Remove the plug from the slot and insert a flat-head screwdriver to turn the starwheel. Adjust the tension until the wheel will no longer spin. Then, back off your turns one notch at a time until the wheel is spinning with minimal drag.
