You are correct that the wheel bearing is bolted to the knuckle, but the hub is press fit into the bearing. These days in newer cars you buy the hub and bearing as a set, so you don't realize how easily the two parts can break apart. It is true that after a few months that press fit of the hub into the bearing is so solid on the inner race that it is very difficult to get off. So, the weakest link of the chain fails first, the bearing cage. That bearing cage is made from thin sheet metal! If the axle nut comes off, and the wheel is subjected to the extreme forces of the road, that sheet metal of the bearing cage tears away and the bearing splits into two parts, with bearings flying everywhere and the wheel and hub flying completely off. With old style press fit bearings, we actually do this with a ten pound slide hammer. A handful of good whacks and the bearing explodes into two pieces. The inner piece stays with the hub, and a snap ring holds the outer race in the knuckle. So, that axle nut is a critical element that keeps your wheel on the car!
A much more accurate way is to use the fact that torque is length * force. So there are a few things you can do, weigh yourself and use a breaker bar to stand on it a distance away that gives you the right torque, adjusting for the fact that you'll be putting slightly less weight on it since you'll have a hand free to balance on something. If you stand 1 foot away on the breaker and weigh 180 lbs that's the right torque at 90 degrees. Another would be to use a scale and jack, put the jack on the scale and the end of the breaker on the jack, then jack up until it's the right measurement. If the breaker is 2 feet long and you need 180 ft lbs jack until the scale reads 90 lbs plus the weight of the jack.
A smart way to figure it out if you have no torque bar--tighten it as when you undid the nut remembering the effort that was required and match the crimp--just what i was looking for--excellent. Just takes a little thinking.
That’s not “turn of the nut method” either. The amount to turn the nut is based on the diameter, length, and grade of bolt used. 1/3 turn may be good for “some” applications, but certainly not all situations.
