Servicing RV Bearings

Safely Jacking Up the Trailer

1. Park the trailer on firm and level ground.
2. Block the trailer tires on the opposite side securely with wheel chocks so that no forward or rearward movement is possible.
3. Jack up the trailer following the manufacturer's instructions using a heavy-duty hydraulic jack.
4. Secure the trailer on jack stands of adequate capacity front and rear.

Remove the Wheel and Hub

1. Undo the wheel nuts and remove the wheel.
2. Pry off the dust cap using a flat-bladed screwdriver.
3. Straighten out the cotter pin that holds the bearing nut and remove it.
4. Remove the bearing nut and washer.
5. Gently pull the brake drum forward while cupping the hub opening with your hand to keep the front bearing from falling to the ground. The outer race stays in the drum, while the inner race and roller bearings come out as an assembled unit.
6. Place the front bearing, bearing nut, and bearing washer in a clean container.

Remove the Grease Seal and Inner Bearing

1. Place the brake drum face down so that the back of the drum is accessible.
2. Pry out the double-lip grease seal. This will be replaced during reassembly.
3. Lift out the rear bearing and place it in the container with the rest of the parts.
4. Don't mix up the bearings if you are doing more than one wheel at a time – each bearing must mate with its original race. The bearings wear in by a certain amount and need to be matched with their respective counterparts.

Clean and Inspect the Bearings and Races

1. Thoroughly clean the bearings and other parts in a solvent (not gasoline!) until all old grease is removed. Set them aside to dry completely or blow dry with compressed air. Don't use air pressure to spin the bearing, as damage could result to the bearing or to your person!
2. Clean the hub and spindle.
3. Inspect the bearing races for heat discoloration, pitting, scoring, and any unevenness.
4. Inspect the bearings for damage as above. Any out-of-round rollers, cracked roller cages, or rough running indicates replacement is required.
5. The bearing and both inner and outer races must be replaced as a set.
6. Inspect the brake drum for pitting and excessive wear, especially if the brake shoes were allowed to wear down to bare metal.
7. Inspect the brake magnet surface for excessive or uneven wear.
8. If the brake drum and magnet have been saturated with grease from a failed seal, replace the shoes and magnet, and have the drum turned or machined to renew the surfaces.

Hand Packing the Bearings

1. Place a walnut-sized gob of high-temp wheel bearing grease in one palm.
2. Grasp the bearing with the other hand so that the wider end is facing the grease.
3. Force the grease into the gap between the inner race and the outer cage so that it squeezes up through the rollers and out the top.
4. Press the bearing down into the grease in a rocking motion and continue until the grease oozes up.
5. Rotate the bearing 1/4 turn at a time, and continue until the bearing is completely filled with grease.
6. Optionally, use an inexpensive bearing packer – there are types used with a grease gun filled with wheel bearing grease and other types where you drop the bearing in and apply pressure to force grease through.

Reassembly

1. Put some grease into the interior of the hub with your fingers. A walnut-sized amount is sufficient. Spread it around the circumference of the hub.
2. Place the inner packed bearing into its place in the hub.
3. Place a new trailer grease seal on the hub and tap it into place with a hammer until it seats fully.
4. Wipe off any grease that finds its way onto the outer flat surface of the seal.
5. Replace the drum onto the axle spindle, insert the outer bearing, thrust washer, and axle nut.

Preload the Bearing

1. Tighten the axle nut by hand until it is snug. Tighten another 1/4 turn with pliers or a wrench while spinning the drum to seat the bearings.
2. Spin the drum several times to distribute the grease evenly in the bearings.
3. Back off the nut with pliers or a wrench until loose, then retighten finger-tight.
4. Insert a new cotter pin to lock the nut in place and bend it over the spindle.
5. Reinstall the dust cap, wheel and tire, and hubcap.
6. Now is a very good time to adjust the brakes. See Adjusting RV Brakes for more info.
7. Wash hands vigorously for 15 minutes! :)

Replacing a Bearing

When replacing a bearing, always replace it as a complete set with new inner and outer races using a quality trailer bearing kit.

1. The inner races are pressed into place in the hub and must be driven out.
2. Use a brass punch to catch the edge of the race by passing it through the inverted hub. A few firm taps with a hammer will drive out the old race.
3. Place the new race into position and tap it in with the hammer and punch. Take care not to mar the surface of the race.
4. Pack, reassemble, and preload the bearing as above.