31-03-17, 11:11 AM
That has always been my view on torquing up nuts and screws.
The setting is determined by the manufacturer to put a specific tension on the shaft of the bolt/screw. They do so using clean smooth threads and can’t offer figures that make allowance for 18 years of road grime and corrosion.
There is a distinction between dynamic friction which is minimal if you go slowly and static friction which is at its maximum when the nut is stationary. Of course, without the latter, the nut would undo itself which is why something… (copaslip, engine oil or threadlock) needs to be present to lubricate the threads while the fastener is getting tightened. Once the nut stops, the film strength of the fluid is exceeded and it is forced away from the contact points. You now need a similar force in the opposite direction to undo it, the tension of the bolt shaft acting via the “gearing” of the thread pitch is far too small a force to overcome the stiction.
(Obviously, Fazer sprocket nuts are the exception.) :lol