Torque check

When I first started in the truck tire and wheel service business as a technician 27 years ago, most wheels and rims were installed with the standard 1-in. impact wrench simply because we didn't know any better. The market was dominated by demountable (or Dayton) rims and stud-pilot (or Budd) wheels, so the goal for most technicians was to keep the rims from spinning and the inner and outer cap nuts

When I first started in the truck tire and wheel service business as a technician 27 years ago, most wheels and rims were installed with the standard 1-in. impact wrench simply because we didn't know any better. The market was dominated by demountable (or Dayton) rims and stud-pilot (or Budd) wheels, so the goal for most technicians was to keep the rims from spinning and the inner and outer cap nuts from breaking. There were a few fleets that understood the importance of proper fastener torque, but for the most part, the industry followed the “good-and-tight” approach.

A lot has changed since then. Hub-pilot wheels dominate the industry, while demountable rims and stud-pilot wheels are primarily used on older equipment and a few specialty applications. The good-and-tight method for installing fasteners with an impact wrench still exists, but thankfully it is being replaced by torque wrenches and other tools that can deliver precise amounts of force. More and more fleets and tire dealers are realizing the importance of proper fastener torque because none of the hub, drum or wheel companies recognize impact wrenches as torque control devices.

But torque wrenches are not magic wands that mysteriously guarantee the wheels or rims will stay on the vehicle. Every system has its own recipe for success and if the step-by-step procedures are not followed, the end result can be loose components — even if they were installed with the proper torque. The key factor for wheel and rim retention is clamping force, which cannot be measured in the field. Therefore, technicians must be trained to follow the recommended guidelines before tightening the fasteners with a torque wrench.

Although technicians can perform each step of the installation process and torque the fasteners to the exact specification (with a calibrated device), the wheels or rims can still become loose. For decades, the industry has recommended retorquing the fasteners after the first 50-100 mi. in order to identify components that may be in need of replacement or assemblies that were not properly installed. As someone with experience in legal proceedings, I believe the word retorque implies that it wasn't done correctly the first time, so I've made it my personal mission to replace it with the words torque check.

There should be little confusion when deciphering the meaning of a torque check. It implies that the fasteners were installed with the proper torque and then checked down the road. And while many drivers and fleets ignore the disclaimer at the bottom of most invoices that states that a retorque or torque check after the first 50-100 mi. is required, failing to abide by that warning can have catastrophic results. Like all mechanical components, degradation over time is unavoidable. Wheel studs and fasteners gradually wear out, but it is extremely difficult (if not impossible) for technicians to visually identify certain types of damage. That is why the torque check is so important.

In all honesty, I doubt there are many fleets in North America that can guarantee none of their wheels or rims have ever been installed good-and-tight. If the overtorque was severe enough, the stud could be weakened, or yielded. And while this type of damage from a previous installation cannot usually be seen, it can be identified during a torque check because the fastener may show significant movement in a tightening direction as a result of the loss in bolt tension. The torque check is not the only method for identifying a yielded stud, but it's probably the most realistic and doubles as the best practice for preventing wheel-off accidents.

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