How To Use A Torque Wrench
Did you know that more problems are caused by over-tightening than under-tightening.
Do you really need a torque wrench?
You may think you don’t need a torque wrench set to install spark plugs or work on your lawn and garden equipment. But studies show that over-tightening is a lot more common than you might think. And over-tightening leads to broken bolts, stripped threads and damaged equipment.
With a torque wrench set and the manufacturer’s torque value in hand, the problem is solved: A “clicker” torque wrench makes an audible click when you’ve reached the set torque, and with a “beam”-style wrench, you just watch the scale and stop at the right number.
Torque wrenches come in four styles: clicker style, bending beam, dual beam and digital. Dual beam and digital wrenches are the most expensive ($200 to $400), and they’re overkill for most of us. You simply don’t need to spend that kind of money to get accurate results. As long as you follow our usage tips, you can torque nuts and bolts with any of these wrenches. Check out our story on the 26 tools every mechanic needs.
Pro-quality clicker-style micrometer wrench set
You’ll have to spend close to $100 to get a pro-quality 1/2-in. drive clicker-style torque wrench. Sure, it’s a lot more than for a cheapo wrench. But at least you’ll be getting a wrench that’ll hold its calibration longer. Better yet, most of these wrenches carry at least a one-year warranty and can be recalibrated and repaired after the warranty period. This is a Kobalt 1/2-in. drive 50–250 ft.-lb. torque wrench.
Bending beam torque wrench set
A bending beam (aka ‘deflecting beam’) torque wrench holds its calibration forever if you don’t drop it. This one is 30 years old, and it still works fine. You can buy them at home centers and online (one choice is the Neiko Classic Needle-Style Dual 3/8-in. & 1/2-in. drive, 0-150 ft.-lb. Torque Wrench). The downside to a bending beam wrench: You must view the scale from directly above the needle. That’s hard to do when you’re using it in close quarters or at an angle.
Economy clicker-style torque wrench sets
You can find economy clicker-style torque wrenches at most home centers and online (such as the Storm 3T415 1/2-in. drive wrench). They work well if you just need a torque wrench for a single tightening project. But economy torque wrenches don’t hold their calibration very long, and most calibration services won’t recalibrate them. Consider it a disposable ‘one-project’ tool.
Set the torque
Did you know there’s a right and a wrong way to tighten lug nuts? Most people think “tighter is better.” This is not true. Over-tightening lug nuts is the number one cause of brake rotor lateral runout (warp). Warped rotors cause pedal pulsation and can increase your stopping distance. Over-tightening is also a great way to break wheel studs. The stud itself doesn’t cost much, but the labor to press out the old stud and insert the new one can be significant.
Spin the lug nuts on by hand. Never coat the stud with grease, oil or anti-seize. Lower the jack only enough to bring the tire into contact with the road. Tighten each nut to one-half of the specified torque. Then lower the vehicle completely and tighten each nut to full torque.
Pro Tip: For the best results, move the socket from one nut to the next in a star-shaped pattern. (See Below)