Checking the bearings inside the wheel support to see if they need replacement or maintenance is critical to the safe operation of your RV.
Here's a step-by-step guide to maintaining these important pieces of RV equipment during annual maintenance checks.
1) (Dis)assembly required
When removing a tire from a trailer, it is important to take extra care: damaging the hub or spindle while removing components can turn a simple maintenance job into an expensive complete assembly repair.
Remove the tire and wheel assembly, hubcap, cotter pin, adjusting nut and washer. Then, gently pull the hub assembly toward you, which will loosen the outer bearing cone assembly. Once loose, remove it and pull the hub assembly off the axle. This should include the inner bearing cone assembly, inner cup, outer cup and gasket. Using a seal puller, remove the seal, exposing the inner bearing cone assembly. Discard the gasket and remove the inner cone assembly from the hub bearing.
Evaluate bearing assemblies. If they are damaged or corroded, it's time to replace them using a cup wrench or mild steel bar to remove the inner and outer cups from the hub assembly. If they are not damaged and you are just cleaning the assemblies, you can skip this step.
Once the assembly is separated, evaluate the condition of the bearing.
2) Evaluate the bearing
Using kerosene or mineral spirits, remove all old lubricant from the hubcap, hub assembly, spindle, bearings and caps, as well as other components. Once the surface is clean, you can assess whether there is significant damage to the hub and spindle.
If the damage is minor (debris, chips or burrs), remove it with a fine file, wire brush, sandpaper or sharpening stone. If the damage cannot be repaired, it is time to replace the hub and spindle.
Then examine the bearings and cups for signs of wear, discoloration, pitting, pitting or other types of damage. If necessary, replace the bearings and caps.
3) Adequate lubrication
Apply a thin layer of grease to the axle, races, seal and inside the hub and hubcap. Grease prevents dry starts and protects metal components against corrosion and premature bearing damage.
Then apply an approved grease to the tapered roller bearings. When using traditional greases (NLGI #1 and 2), you must force a ring of grease around the entire circumference of the wheel hub until it is half full. If the hub is more than half full, it can cause shaking and higher temperatures, which can damage the bearings. Then cover the inner wall of the shell.
4) Reinstall the hub
Use a screwdriver or mild steel bar to insert the inner cup and outer cup into the hub assembly until they are firmly in place against the hub lugs. Be careful not to damage the cup surfaces and never use a tapered bearing assembly to drive the cup.
At this point in reassembly, you will need to install the inner bearing cone assembly and replace the oil seal. Follow the manufacturer's specifications for the direction of the sealing lip. Use the appropriate installation tool to avoid damaging the gasket. Then slide the hub assembly back onto the shaft, being careful not to damage the seal against the shaft. Finally, install the outer bearing cone assembly, washer and adjusting nut onto the shaft.
| Take note: |
| Always follow the trailer/axle manufacturer's maintenance schedule recommendations. Consider servicing your trailer's wheel bearings before storing it for long periods of time. Moisture in the hubs can cause corrosion of the bearing assemblies. |
5) Bearing adjustment
After reassembling the hub assembly, it is important to ensure correct bearing adjustment. If the adjustment is not correct, it will reduce the service life of bearings, seals and other components related to the shaft end.
First tighten the adjusting nut to 25 foot-pounds while turning the hub. This should create a slight restriction in the bearing, indicating that the parts are positioned correctly. Back off the adjusting nut one-sixth to one-quarter turn to allow 0.001 to 0.005 inch end play. Place the locking clip on the adjusting nut and insert the cotter pin to prevent the adjusting nut from binding.
Using a dial indicator, mount the base as close to the center of the cube as possible. When it is close to the center of the spindle, set the indicator to zero. Hold the rotor at the 3 and 9 o'clock positions and push it axially while rocking the wheel back and forth. Stop and read the indicator. Then do the same by pulling the rotor towards you.
The end play of the bearing is equal to the total movement of the indicator, which should be 0.001-0.005 inches. If not, turn the axle nut in the appropriate direction and recheck the bearing clearance.
After completing all checks, reinstall the hubcap and tire and wheel assembly, remembering to tighten the nuts according to the manufacturer's recommendations.
