One of the leading causes of premature hub failure is improper torquing of the axle nut. Most drive axle hubs have a center nut that must be torqued down onto the axle shaft to a specific torque value.
Putting the proper torque on the center nut sets the preload for the bearing and keeps the bearing from separating while in operation. The torque specification for this center nut is critical to the performance and longevity of the hub. The correct torque spec is available from a number of sources including SKF’s Torque Specification Guide (Form # 457377).
This guide contains torque specifications and procedures for properly securing all domestic and import wheel bearing units. Torque specifications can also be found in SKF’s online catalog in the Application listing section.
Also note some hubs come with a new nut in the box. This is typically when a one-time use self staking nut secures the hub. In these applications, a new nut must always be used when installing a hub. Reuse of the old nut could potentially cause the nut to loosen during vehicle operation.
Remember: Many vehicles require the wheels to be on the ground for final torquing to OEM specifications. This assures the proper mating of the split inner rings of the bearing needed to achieve the proper internal clearance. For specific mounting instructions, refer to the vehicle manufacturer’s service manual for that model.