Most of these old stovebolts have 7/16-20 lug studs, not 1/2-20 lugs like more modern vehicles. The proper torque for a 7/16" stud is around 70-75 ft-lbs., not 100 or so for a 1/2" srud. An air wrench can exceed 70 pounds with one good rattle, and the stud is sitting there at or near its breaking point while you merrily ride along, unaware of the danger. Another thing- - - - -if 5 or 6 lugs are not torqued equally, the tightest one holds almost all the clamping force until it stretches or breaks- - - -then the next-tightest one takes over, etc. The remedy is to use a torque wrench to be sure all the studs are tightened equally. Try this- - - - -get 5 people to hold up a 400-lb. weight for a while. The 5 foot 3 guy won't be holding as much weight as the 6 foot 4 one, right? When the tall guy gets tired and lets go, the next-tallest one gets most of the load. The same idea applies to lug nuts!
Jerry
