Manufacturer specifications apply. This page explains concepts only. Torque values, clearances, preload, backlash ranges and procedures vary by axle model and must come from the vehicle or component manufacturer's service information. This directory does not publish repair specifications.
What this service covers
Commercial truck and trailer wheel ends are made up of the hub, tapered roller bearings, hub seal, lubricant and the retaining nut system. Correct bearing adjustment is critical: too loose or too tight can lead to overheating and wheel-end failure.
Many newer trucks and trailers use pre-set or unitized hubs that change the procedure. Technicians must follow the procedure for the exact system.
Common signs
- Leaking hub seal or lube on the wheel or brakes
- Hot hub after a run
- Wheel play or bearing noise
- Lube level low in an oil-bath hub
What the work usually involves
- Inspect lube level and condition, seals and wheel end play
- Disassemble, clean and inspect bearings and races
- Install a new seal and set bearing adjustment by the specified method
- Verify end play and lube level
Steps vary by vehicle and component design. Values and procedures come from the manufacturer's service information.
Vehicles this applies to
Class 6–8 trucks, tractors and trailers.
Key terms
Full-floating axle
The wheel hub rides on its own bearings on a spindle that is part of the axle housing, so the housing carries the vehicle's weight and the axle shaft only transmits torque. Common on many 3/4-ton and 1-ton pickups and on commercial trucks.
Wheel-end bearing
The bearings that support the hub on the axle spindle. Heavy trucks commonly use tapered roller bearings, either adjusted using a specified procedure or supplied as pre-set or unitized assemblies. Adjustment procedures come from the axle or hub manufacturer.
Hub seal
The seal at the inboard side of the hub that keeps oil or grease in and keeps water and dirt out. A leaking hub seal can contaminate brakes and lead to bearing failure.
Choosing a shop
- Confirm the shop works on your vehicle class and, for trucks, your axle make.
- Ask what parts they install (new, remanufactured or rebuilt) and what warranty applies.
- Check the listing's verification status and date in this directory.