The hub bearing serves to secure the wheel hub, or rotor, into place on your vehicle's axle. Other names for the hub bearing include the hub nut, axle spindle nut or axle hub nut. It is important that the hub bearing is tightened adequately when servicing a vehicle's axle components. The hub nut must be removed in order to resurface or replace rotors, replace CV joints and many other components of the vehicle's axle system.
Although every vehicle's exact specification of the torque range for the axle's hub nut can vary, the torque should be set at or near 175 foot-pounds (225 Newton-meters). It is important to use a torque wrench, which can be set to measure the amount of torque being generated when tightening the hub nut.
Most vehicles do not require any specialised tools or adaptors in order to remove the hub nut. However, turning the hub nut in order to loosen it will often spin the rotor. If this happens, wedge a pry bar or tire iron between two wheel studs, found on the rotor, and rest one end of the pry bar on the ground. This will prevent the rotor from turning while unscrewing the hub nut.
A hub nut that is too loose may lead to premature wheel bearing failure. As a worst case scenario, the hub nut may also loosen so much that the entire wheel assembly along with the tire comes off the vehicle while travelling. This could lead to catastrophic axle damage as well as potential for an accident. Alternatively, if the hub nut is too tight, then the wheel hub may not spin properly, leading to bearing damage as well as extra power needed to turn the entire wheel. This will also result in a decrease in fuel economy.
Some vehicle designs utilise hub nut rims and spindles as part of the hub nut assembly. Certain repair manuals also suggest replacing the hub nut, usually just a few dollars, whenever it is removed from the rotor. If a hub nut cover is used, it is often suggested to replace it as well.