U Bolt Torque Thread (Rusty Calling You)

As stated above, leaf springs don't move in the middle, but the ends of them do rub against eachother. Look at where the arch is, not much in the middle where the u-bults go.... think about it! If, as pishta said, 45 ft/lbs is 5400 lbs clamping force, how much do you really think they are rubbing against each other in the center part under the u-bolts? Tightening them down more is gonna cause them to rub less in the middle where they are not rubbing at all anyway?

Anyone ever clamped them up and measured them when applying a certain load? That would be interesting to see the results!