During the past 15 years I have investigated at least 30 "lost wheel" claims against so-called "professional" shops such as Firestone, Goodyear, Walmart, "Budget Brakes", "Tires Plus", a bunch of independent shops, and quite a few car dealerships. A noticeable number of them involved obviously overtorqued lug nuts which resulted in broken-off studs due to stretching of the threads. Most of these situations resulted in serious body damage to the vehicle involved. Some of them totaled the vehicle, and/or resulted in injury to the driver, passengers, or innocent people who just happened to get in the way of the runaway wheel. I've briefed attorneys on the type of questions to ask me in the event I'm called upon to be an expert witness in litigation. So far, nobody has wanted me to take the witness stand and explain the mechanical malpractice that results in the loss of a wheel. Several very large damage settlements were made in lieu of a trial.
If anyone chooses to install a wheel stud by pulling it into place with a nut, PLEASE use a torque wrench and do not exceed the recommended torque that would normally be used to install a wheel. On the 7/16-20 lug studs used on a lot of vintage stovebolts, that torque is less than 75 ft/lbs. On a 1/2"-20 stud, 100 ft/lbs. is a pretty good practical limit. Once a thread has been stretched beyond its "yield point", loosening the nut and retorquing it does not reverse the damage that has been done.
I've got a pretty thick skin- - - -I can handle a little ridicule, sarcasm, and mockery when I express some concern for my fellow stovebolters' safety, as well as that of the people who share the road with them, and the continued good condition of the vehicles they spend so much time and effort restoring.
Press on!
Jerry
