Unit bearing assemblies are designed to be correctly preloaded by accurately torquing the wheel hub nut on the spindle. Manufacturers warn of premature bearing failure if not torqued to the proper value. We’ve seen mechanics zip the spindle nut on with a big air impact tool. However, use of an impact gun is not recommended as it can shock load the CV joints on a drive axle or damage axle threads. Some spindle nuts are also single-use items and are meant to be replaced with a new one once removed.