That click–so familiar to anyone who’s spent time getting their hands dirty in the garage. That satisfying little pulse in your hand that signals a job well done. It’s a welcome piece of audible and tactile feedback to enthusiasts everywhere.
Torque 101
When we talk about measuring fastener torque, what we really want to know is the clamping force: How tightly are two surfaces smooshing against each other under a connection secured by threaded fasteners? This is one of the critical forces engineers consider when they design something.
Unfortunately, you can’t directly measure clamping force. Doing so would require some sort of sensor sandwiched between the two objects, which would naturally conflict with the mission of pressing them together.
So we do the next best thing: extrapolate clamping force via the amount of rotational force the threaded fasteners are exerting–also known as torque.
Click, Click
Torque wrenches–at least the “click” types that we’re mostly dealing with here–all work similarly. They’re multipiece designs featuring a hinged head near the end of the handle.
Without tension, the head would be free to flop back and forth, but the adjusting device–one calibrated for the desired amount of torque–places a preload on that head. Usually this is done via a ball-and-spring arrangement featuring a detent or similar load-based positional retention system.
When the user overcomes the maximum preload of the retention system, the head breaks away from the retention device and the handle moves independently of the head. This causes the “click” familiar to anyone who has ever used a torque wrench.
Torque wrenches are calibrated at the factory, and just about all of them–even the cheap ones–come with a calibration form containing some sample set torque values against the actual measured values. These should be within the manufacturer’s claimed accuracy for the wrench. (And if they aren’t, the wrench probably won’t leave the factory.)
This data allows the user to build a profile for the wrench. For example, if the testing shows that the wrench always produces 2 percent more torque than the desired setting, then the user can set the desired torque 2 percent below the recommended setting. Or just live with the extra oomph.
Since these are mechanical devices subject to wear, most decent torque wrenches can be recalibrated. Sometimes this takes the form of a different rate spring holding the detent mechanism; other times it’s a simple preload adjustment via a hidden screw. Premium wrenches typically have calibration guidelines in their manuals. (You totally kept the instruction manual, right?)
But you also have to know how accurately your wrench is reading, and for that there’s test equipment. The Snap-on torque checker we used retails for $550, but any tool truck should have one on board for customer use.
Each wrench manufacturer has specific recommendations for calibrating its equipment, but typically you should calibrate a wrench every year, or every 5000 cycles, or after any major trauma (meaning dropping the wrench on a concrete floor, not losing $2500 in an ill-advised hockey bet).
SONIC TWO-WAY TORQUE WRENCH
sonictoolsusa.com
Sonic Tools is new to America, as the company arrived in our market early in 2015.
- The feel of the Sonics is among the best in our comparison lineup, and the action of the adjustment lock is positive and definitive.
- Both the n/m and ft./lb. scales are off center and slightly distorted by their window displays, making them a bit hard to read.
- Like most of the wrenches in our test, the Sonics had better-than-claimed accuracy.
FINAL THOUGHTS: The plastic grip and textured finish beam feel nice, although we suspect the grip will get dirty sooner rather than later with heavy use.
USAG TORQUE WRENCH
griotsgarage.com
Griot’s Garage now carries tools from USAG, an Italian firm dating back to 1926.
- These are scaled only in n/m, which may limit their appeal for some users.
- As accurate as any wrench in the group and feel great in the hand–but at those prices they’d better.
- Very comfortable handle.
FINAL THOUGHTS: If you can live without a lb.-ft. scale and don’t mind the price, these are worth a look, but others we tested provide more bang for the buck.
ICON TORQUE WRENCH
harborfreight.com
Earlier this year Harbor Freight launched Icon, billed as its premium tool line.
- The stamped scale can be slightly hard to read, but it’s better than the stamped scale on most low-end wrenches.
- The all-chrome construction doesn’t feel quite as nice in the hand as the plastic-gripped wrenches, but it should clean up better and for longer.
- Great accuracy, great action, smooth 90-tooth ratchet, and a great price. What’s not to like? Very little, actually.
FINAL THOUGHTS: If we had to buy a torque wrench tomorrow, we would choose one of these Icon pieces, hands down.
QUINN DIGITAL TORQUE ADAPTER
harborfreight.com
This battery-operated device, purchased via Harbor Freight, turns a ratchet into a digital torque wrench.
- Accuracy wasn’t great, but the actual accuracy was within that claimed by many common torque wrenches.
- The lack of a mechanical “click” means it can be tricky to use, especially at low torque settings.
FINAL THOUGHTS: For less than $30, it’s probably not a bad addition to your toolbox, but you probably won’t want to use for extremely sensitive assemblies.
KOBALT ½-INCH DRIVE PROGRAMMABLE ELECTRONIC TORQUE WRENCH
lowes.com
Kobalt, launched in 1998, serves as Lowe’s house brand.
- The digital readout is highly accurate.
- The lack of mechanical release when torque is achieved means the user has to develop a feel for the wrench and listen closely to the audible warnings.
FINAL THOUGHTS: Sadly, there’s not a compelling reason to recommend this wrench when there are so many other good, less expensive choices out there.
PRECISION INSTRUMENTS SPLIT-BEAM CLICK WRENCHES
torqwrench.com
We borrowed this tool from a professional mechanic friend, and he admitted that it was high-mileage and due for a tune-up.
- While it was the least accurate in this test, it was also the most consistent. Properly calibrated, in theory, it should be up there with the best of them.
- The dual-beam action feels nice and breaks away cleanly when proper torque is achieved.
- The dial scale is also easy to read and easy to adjust.
FINAL THOUGHTS: Thumbs up for a quality piece.
THAT $20 TORQUE WRENCH THAT EVERYONE OWNS
harborfreight.com
We also tested a couple of those ubiquitous $20 torque wrenches that can be found at Harbor Freight, Northern Tool, Tractor Supply and Walmart.
- The stamped numbers are a bit hard to read, and the ratchet and breakaway action doesn’t match that of the premium wrenches, but what the hell do you want for $20?
- Accuracy was darn good for the money. We tested several of these and never found one more than 4% out of whack. Some read within 2%.
FINAL THOUGHTS: Everyone should keep one of these in every toolbox or trailer and use it for the less sensitive stuff. Plus, it’s a great loaner. Think of it as a hammer that actually does some fairly accurate torqueing.
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Photography by J.G. Pasterjak
