As much as 90% of all wheel end seal failures are a result of improper installations, according to SKF.

The manufacturer offers a systems approach to wheel-end maintenance in its Trouble Free Operation program, by providing fleets with detailed instructional materials and making hands-on training available to technicians.

The following tips are from the program’s Wheel-End Maintenance Guide.

Removal procedures

• Removal of the wheel assembly should always be done with a wheel dolly.

• Grease or oil seals should be removed with a special seal removal tool to avoid damage to the hub. New seals must always be used in replacement.

• Bearings and seals should be inspected for wear or signs of probable failure.

Installation procedures

• Bearing cups should be installed using a special bearing installation tool. A hammer should never be used directly to drive bearing cups into position!

• Seat seals in the bore using a special installation tool with centering plug. Never use direct hammer blows on the seal – it will destroy the seal’s ability to contain lubricants and protect the bearings.

• Re-mounting of the wheel assembly on the spindle should always be done using a wheel dolly. Be careful in moving the assembly onto the spindle because it is necessary to avoid damaging the seal.

• Spindle nut torque adjustment should follow the manufacturer’s specification on TMC RP618. Endplay adjustment should be verified using a portable dial indicator.

Inspection of grease or oil can provide a clue to other problems. Remove a sample from the wheel end and check condition of the lube:

• Cloudy or milky indicates water

• Shiny indicates bearing wear

• Metal flakes present could indicate loose shavings from an axle component

• Grit and sand indicates lube contamination

• Burnt smell indicates overheating

Bearings must be cleaned for inspection and re-use. Use only clean solvents. Good cleaning requires proper equipment such as a solvent bath and a filter system with regular changes of both.

• Do not use compressed air. Air jets cause small abrasive particles to become jammed in between the bearing surfaces.

After cleaning, dry with a clean paper towel or a clean rag. Prior to re-installing bearings, always check for the proper lubricant. The truck or trailer manufacturer has pre-determined that the wheel-end assembly is to be lubricated by either grease or oil. The importance of following the manufacturer’s specifications cannot be over emphasized.

• Always use specified lubricant

• Do not mix lubricants. Chemical interaction between lubricants and seal materials can damage the seal

• For proper lubrication, the grease must be packed into the cavities between the rollers and cage of the bearing cone. A mechanical grease packer is recommended

• Apply a light film of grease to the axle spindle for corrosion protection.

• It is important to not mix wheel-end components – bearings are “mates” that wear together. This includes new bearings.