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THE IMPORTANCE OF PROPER WHEEL TIGHTENING
Have you ever gotten into a car and while driving along stepped on the brake and the whole car shook and vibrated? It is an annoying and costly condition to fix. It is referred to as brake rotor runout and/or thickness variation and the leading cause of it may surprise you.
Improper tire/wheel torque is number one reason why brake rotors have this condition. The tool that automotive technicians use to install wheels is called an impact wrench or more commonly referred to as an air gun. It is used to save time when removing and installing multiple fasteners but is NOT meant to final tightening of anything. Just like its name implies, impact means that there is a hammer feature built into that tool. Using this tool in this way is the equivalent to banging the wheel/hub/rotor assembly with a hammer! That would result in even clamping forces on the assembly causing brake pulsation. The proper way to install a tire/wheel assembly is to run the lugs on low power and then tighten with a torque wrench in a star pattern to provide even clamping force.
When we remove wheels for any reason, we tighten with a torque wrench and then I road test the vehicle and torque them again. The wheel could have seated itself during the test drive and retorquing will address that.
So the next time you see a automotive technician “hammering” a wheel on with and impact gun ask him where his torque wrench is.
