As an RV operator, you will find it useful to learn whether your motor home steer axle is equipped with oil bath hubs or a grease pack.

A grease pack is located inside the hub and next to the bearings, and as the name implies, is packed with wheel bearing grease for stability. Heat will affect most types of grease. A grease pack is particularly vulnerable if the brake linings are worn down metal to metal. Heat damage to the grease pack can contaminate the grease, and affect proper performance of the seals and the spindle.

Units with an oil bath hub have a front axle lubricated with oil. When the bearings are moving, they are swimming in oil. Front seals on the oil bath hub should be regularly inspected, and a visual check for oil leaks should be frequently performed. If a seal becomes compromised and oil leaks while driving down the road, the front axle and bearings are likely to be damaged.

Oil bath hub systems use no grease, and are instead designed to rely on fluid. Each time the wheel moves in an oil bath system, the bearings are moving in oil. Oil bath hub systems reduce the need to repack wheel bearings. Oil leakage present at the hub may indicate that a seal at the oil bath hub needs to be replaced.

Oil bath hubs and grease pack axles are generally designed in different ways. If the front axle is equipped with a cover over the front hubs, remove this wheel cover to study the center hub. If the axle is equipped with oil bath hubs, you will be able to view the oil level. If the axle is a grease pack, all that will be visible is the end of the cover.

Pre trip inspection of the wheel bearings is essential. Before undertaking the pre trip inspection, park the motor home on firm and level ground, set the parking brake and for added security, chock the front wheels. Begin at the curbside front of the motor home and walk around using sight and smell to detect abnormalities around the steer axles. Inspect the wheel ends for any evidence of leaking lubricant, damaged or missing parts. It may be difficult to inspect the inside of the brake linings without crawling under the RV. Signs of oil, or the odor of burning and grease and oil are early signs of a potential leak, and should be promptly inspected and repaired as necessary. Small amounts of oil leakage are normal. If the vent becomes plugged and oil is leaking out in large amounts, chances are that the system is experiencing a problem.

During drive time pay attention to noise that may emanate from the wheel bearings, and promptly inspect unusual sounds. Create a routine pattern of walk around inspection to protect you from overlooking one of the wheels. At each stop, walk around the motor home and touch the hubs with a bare hand. It may take some time to learn how warm the hubs will usually feel, but generally can be considered overheated when the hub is too uncomfortable for a prolonged touch. An overheated hub will usually emit a burning odor. Changes in temperature, or any sign of excessive temperature, should be promptly investigated for potential repair.

Lubricant used in the bearings will protect components from excess heat and corrosion, reduce friction and prevent metal-to-metal contact. To insure proper wheel bearing operation, adhere to the component manufacturer's recommended replacement lubricant. All-purpose lubricant may appear to save you money up front, but could damage the wheel bearings over time from exposure to improper viscosity or harmful additives.

Coaches that utilize the grease pack on the front steer axle require careful adherence to the OEM specifications when repacking the bearings. Once the hub and bearings are removed, all old grease should be thoroughly cleared away to allow for cleaning of the inner and outer bearings using solvent. After cleaning, the inner and outer bearings and races are carefully inspected for pitting and scalding. Once everything checks out, the bearings are repacked and put back into place using a new seal. All used oil and solvent must be properly disposed. For best results, have the wheel bearings serviced by a qualified RV chassis technician.

An effective way to check the wheel bearings on grease packed steer axles is to inspect the bearings, or to remove the outer bearings and check the grease inside of the cavity. Front wheel bearings can be checked when the tires are off from the ground by turning the tire around and listening for noise, and then moving the tire up and down to check movement of the wheel bearing. Most repair facilities that offer front brake repair will generally handle this type of job.

Water contamination is damaging to both oil bath and grease pack systems. Moisture can occur when the RV is not being driven and cause condensation to form in the grease and oil. Traveling in high humidity can also generate increased moisture exposure to oil bath and grease pack systems. Excess winter climates including rain or freezing weather conditions are additional factors that make annual maintenance of the RV wheel bearings a matter of utmost importance.

Regularly monitor performance of the RV wheel bearings and pay attention to sight, sound and smell. Carefully record wheel-bearing maintenance, including receipts, for future reference.