Whether you’re performing DIY maintenance on your daily driver or find yourself turning wrenches for a living, every mechanic needs a torque wrench in their toolbox. In fact, like pairs of shoes, you should probably have more than one to suit various applications. As a result, you may have questions such as “Why do I need a torque wrench?” and “How do I choose one?”
What is a torque wrench?
Torque is the amount of twisting force used to tighten (or loosen) a threaded fastener like a nut or a screw. From Bob Vila, we learn that a “torque wrench sets the torque limit” used to tighten bolts and nuts like those used on our car’s engine and lugnuts.
Automotive engineers use measurements like inch-pound (in-lb) for small fasteners and foot-pound (ft-lb) to set design limits on torque based on the strength needed by the connection. For example, an over-torqued fastener could break or strip its threads during assembly or use, whereas an under-torqued condition could loosen and fail.
Bob Vila’s picks for the best models
As for the best torque wrenches? Bob Vila ranked the TEKTON 1/2 Inch Drive Click Torque Wrench 24335 as “Best Overall” based on its all-steel construction, plus or minus four percent accuracy range, and its broad 10 to 150 lb-ft torque range.
Rated as the “Best Bang For The Buck,” the Capri Tools 31000 Torque Wrench features a smaller head size thanks to its 3/8 “drive lug compared to 1/2 “drive models and features a lower range of 10 to 80 lb-ft of torque with the same four-percent accuracy rating of a larger wrench.
The “Best Digital” award goes to the GEARWRENCH 1/2″ Drive Electronic Torque Wrench. This model features warning vibration, light, and sound when reaching the desired torque level to prevent over-torquing. The GEARWRENCH digital torque wrench features plus or minus two percent accuracy during clockwise operation and three percent counterclockwise. It also has a larger range capable of applying from 22 to 250 lb-ft of torque.
Are digital wrenches more accurate?
While digital torque wrenches are not inherently more accurate than quality examples of other styles, they do have features that make them easier to use accurately. Most fall into three style categories, beam, adjustable, and digital.
Beam-style torque wrenches use force applied to the handle to move the beam or a pointer along a scale without internal parts or necessary adjustments. They are inexpensive, maintenance-free, and easy to use. However, they provide low levels of accuracy and present ample opportunity to over or under torque fasteners with no warning.
Adjustable style torque wrenches most often provide a click sound and feel when reaching the set torque value. A quality click-style adjustable torque wrench is easy to use accurately when appropriately used. However, it is possible to over-torque by “going past the click,” and setting the value requires correctly reading the torque wrench’s scale.
Digital torque wrenches have easy-to-read LCD screens that display values applied to a fastener. Most also choose to preset a torque value or range and provide an alert when reaching that preset with a sound, vibration, and indicator light. Some models show a green light if torqued correctly or a red light if not after each application. Downsides include higher initial investment, the need for batteries, and reduced relative ruggedness of the tool.