One of the first things a teenager learns when they get their driver’s license is how to change a tire. Loosen the lug nuts, raise the car, remove the lug nuts, and replace the tire with the spare. Tighten a lug nut, then tighten the one that is diagonally opposite to ensure the tire is seated evenly. Repeat until all the lug nuts are tightened. Lower the car and repeat the pattern to make sure everything is tight. It is one of the simplest automotive repairs, and customers find it infuriating when an automotive repair shop makes a mistake tightening lug nuts.
In all fairness, when most people think of changing tires, four-way lug nut wrenches, combination jack handle/lug wrenches, and impact wrenches come to mind—none of which offer precision torque control. A lug nut torque wrench, however, does offer the needed control. For automotive shops whose reputation depends on the quality of their work, mistakes made tightening tires can destroy their customer base, and that’s why lug nut torque wrenches are a worthy investment.
Accidents Due to Improperly Tightened Lug Nuts
Nearly everyone who has worked on vehicles has had the experience of purchasing new tires and then being unable to remove them for maintenance. What follows is a frustrating sequence of methods that are definitely not approved by the manufacturer, including standing on the wrench, jumping on it, hammering on it with whatever happens to be available, and sliding a long pipe over the wrench in an effort to get more leverage. The outcome is usually a sheared through bolt or a nut that is rounded off and must be cut off. This is usually followed by a solemn vow to never return to the shop that created this nightmare.
Losing a customer is far from the worst that can happen, though. Insufficiently tightened lug nuts can come loose at highway speeds and can hit with enough force to go through a body panel or shatter a windshield. A loose lug nut almost certainly means that the wheel is not seated properly. A wheel wobbling around its axis will eventually shear through the rest of the bolts and roll free with potentially catastrophic consequences. Lug nuts that are over-tightened or tightened while cross threaded can produce similar results.
Mechanics are liable for damage caused by negligent or improper repairs and may be responsible for making restitution. If a nut or a whole wheel comes off at highway speeds, the damages can be substantial.
Causes of Incorrectly Torqued Lug Nuts
Improper lug nut tightening is often caused by the use of impact wrenches. Automotive repair shops need to remove and replace tires frequently throughout the day. In order to speed things up, many of them use a pneumatic impact gun. These not only turn but employ a hammering motion to help break stubborn bolts and nuts loose. Unfortunately, these tools can also turn fasteners at the wrong time. A cross threaded lug nut—where the threads are improperly aligned with the bolt—is obvious when you are tightening it by hand. An impact gun, however, exerts enough force that the nut can spin past this impediment. Cross threaded lug nuts are nearly impossible to remove with hand tools, and if the driver finds themselves with a flat tire later, they will have a serious problem.
Misaligned threads can also stop the lug nut short. Sometimes, even the power of an impact gun is insufficient to overcome the friction of fastener threads at crossed angles. Although the lug nut is placed under extraordinary force that may exceed its torque rating, it is still short of the rim. As a result, the tire is seated at an angle. When the car moves and the tire rotates, it will wobble and the wobbling will eventually shear through the bolts holding it.
In order to prevent either scenario, some auto shops forbid the use of impact guns to tighten lug nuts. They are only for removing them. Unfortunately, this is rare and mechanics have been known to disregard the directive. A better solution is to mandate that lug nuts are tightened to the manufacturer’s specifications and provide the tools to meet those specifications exactly.
Choosing the Best Lug Nut Torque Wrench for Your Automotive Shop
One way to ensure that lug nuts are properly tightened is to provide adjustable manual lug nut torque wrenches. The torque specifications for lug nuts vary by make and model, and the exact setting can be found in the owner’s manual or online. The specifications can range from 50 foot-pounds (ft-lbs) to as high as 150 ft-lbs on some vans and trucks. The only adjustable hand torque wrenches with this range are click wrenches. Click wrenches warn the user that they have reached the set torque setting by emitting an audible click, but they do not actively prevent the user from applying more torque than is needed. In some delicate applications, the potential for applying too much torque would make click wrenches unsuitable. However, given that most lug nut tightening is done with a 4-way wrench or an automotive mechanic living out a NASCAR tire change fantasy with an impact gun, they should be more than suitable. Since they are socket wrenches with ratchet heads, they can also be used for everything from lug nuts to spark plugs and would have a place of pride in any mechanic’s toolbox.
Precision power tools are another good choice. Precision air screwdrivers offer much of the same power of an impact gun but far more control over torque. A powerful air screwdriver with a pistol grip shares a power source and a form factor with an impact wrench, making integration into an automotive shop easier. It can also be set to the torque specifications mandated by the vehicle’s manufacturer with one touch. Plus, operators can select an RPM setting to prevent cross threading. A clutch mechanism that shuts off the air supply when the preset torque setting is reached prevents over-tightening. An adjustable pneumatic torque screwdriver offers quick removal and replacement of tires for automotive service or repair and torque control. The combination of speed and control means that this may very well be the best lug nut torque wrench automotive shops can buy.
The reputation of your shop depends on making sure that repairs are done to the highest quality. Incorrect tire fastening is a fundamental error that can destroy your shop’s reputation, even if it only happens once. Lug nut torque wrenches for your automotive shop ensure that lug nights are tightened exactly to specifications, that the wheels stay on, and that the care you put into repair vehicles is always clear to your customers.
At Mountz Inc., we’re committed to making the best lug nut torque wrenches for your automotive shop and the best torque tools for automotive repair and automotive assembly. To see our full range of products, shop our store. Contact us anytime to ask a question. To inquire about price, request a quote. If you’d like to see our equipment in person, schedule an appointment.