A few months ago, I struck a nerve with a few Fleet Owner readers when I stated that anti-seize compounds were not recognized as wheel system lubricants by the fastener, stud, hub and wheel manufacturers. The article was even posted on an Internet trucking forum where someone questioned me as a credible source. I responded by describing a few professional accomplishments and 25+ years of working on truck tires before I finally added the line about the manufacturers.
When an inflated tire and wheel comes off of a commercial vehicle at any speed, it is a 200-lb. unguided missile. It can bounce in any direction and deliver a crushing blow to anything in its path. There's also the issue about losing control of the vehicle and causing a roll-over or chain-reaction accident. It's bad news for the fleet and even worse news for the tire dealer who installed the wheel.
Liability is all about determining what steps were taken to prevent the accident from occurring in the first place. In the event of a wheel-off, one of the easiest targets for a plaintiff's attorney is the torque spec used to tighten the fasteners. If the party in question used anything other than a manual or pneumatic torque wrench, the view under the microscope goes downhill fast.
But even more important than torque is the clamping force, or bolt tension, it creates. This is what actually keeps the wheels on the vehicle. It's like the settings on a grill. My father can light a grill, but we used to call him “old black-is-done” because he didn't understand that everything can't be cooked on high heat and then turned over when the smoke starts pouring out.
Clamping force is all about the recipe, or the steps that are taken to ensure that the proper torque results in the correct amount of bolt tension. If the torque is wrong to begin with, then there's little hope under the microscope. But even if by rare chance the torque is correct, there's still no guarantee on the clamping force because there are a number of factors that come into play, like the condition of the mating surfaces and the fasteners.
Another one of those necessary conditions is dry threads for stud-piloted disc wheels. None of the manufacturers publish lubricated specifications for the old Budd wheels, with the exception of Alcoa who specifies 30-weight oil as the only approved lubricant. And it also includes an accompanying drop in torque of 100 ft-lb. to 350-400 ft.-lb. More clamping force is generated per foot -pound of torque when friction is taken out of the equation, so a lower torque generates the same amount of clamping force.
The use of anti-seize lubricants on stud-piloted disc wheels solves a problem but creates a potential liability disaster. Evidence of an improper fastener lubricant will be easy for the jury to see, so the parade of engineers and expert witnesses will point to the fact that the wheels came off because of improper clamping force caused by the compound.
There are always going to be some old-guard mechanics and tire guys who have been using it for 30 years without a problem. Fleet execs must ask themselves if they're willing to bank on the opinions and experience of guys out in the shop who haven't had an accident for decades. Or, they can follow the physics and engineering that determines the relationship between torque and clamping force with the presence of non-approved fastener lubricants.