Gear Wrench Electronic Torque Wrenches

by Hib Halverson

Since I began working on cars many years ago, my choice in torque wrenches have been either the ancient "beam" type or a dial reading model. I saw GearWrench's Electronic Torque Wrenches (ETW) at the 2015 SEMA Show and I was hooked. I tordered two of them (⅜-drive, PN 85076 and ½-drive, PN 85077), put my old dial torque wrenches on Craig's List and never looked back.

For 2020, the GearWrench people have beefed-up their ETW line by adding three new tools (¼-in drive, PN 85194; ⅜-drive, PN 85195; 1/-in drive, PN 85196) which have all the features of the first generation ETWs as well as a new ability to measure torque-angle and the addition of a 15-degree, flex-head version of GearWrench's proven "120XP" ratchet head.

The key component in an electronic torque wrench is a "strain gauge", a strip of conductive metal inside the wrench's head that has a voltage applied such that current flows though it longitudinally. The strain gauge deforms slightly when torque is applied and, when it stretches, its electrical resistance increases. 

From that change in resistance, the ETW computes the amount of torque that was applied to the wrench head. That data goes to a transducer which converts it to a small current. The ETW uses that current to drive the LCD display screen, a red warning LED, the tone generator and a haptic warning generator in the handle.

 To give the newest GearWrench ETWs the ability to display torque angle, additional electronics were added to sense movement and momentum of the wrench. From that, it calculates angle based on where it starts and where it finishes. No matter how quickly the torque application occurs, this mechanism calculates the change in angle.

In an interview, Paul Steinweg, GearWrench Product Manager, told the CAC, "The integration of torque angle functionality into our ETWs was driven by the market. Not only were automotive service technicians required to reach certain torque specs, but they were more frequently required to apply torque angle, as well. Previously, this could be done with an analog gauge. As we expanded our own line of electronic torque wrenches adding torque angle functionality was a natural evolution."

The GrearWrench, ¼-inch drive Electronic Torque Wrench's measurement range is 2-20-ft/lbs (2.7-27-Nm), the ⅜-drive unit's range is 10-100-ft/lbs (13.5-135-Nm) and the ½-drive's range is 25-250 foot-pounds (34-340 Newton-meters). 

For torque, all three are are accurate to ±2%, clockwise and ±3% counter-clockwise from 20% to 100% of full scale. Torque angle accuracy is: ±1% of reading, ±1 degree at an angular velocity between 10-deg and 180-deg. per sec. and within ± 1-degree of the test fixture used during quality control.

That ½-drive tool goes to 250-ft/lb. is why it has such a long handle. Its length makes tightening fasteners which need 150-ft/lbs. and above, easier. Conversely, the length of the tool might make using it a little difficult on fasteners which torque to 25-50-ft/lb. because of the ease of which you could go past the intended torque. There is a solution. Try the smaller GearWrench ETWs because the ⅜-drive tool is much easier to use when the require tightness is less than, say–40-50-ft/lbs and the ¼-drive unit works better at even lesser torque levels.

Four years ago, the first time we used one of these ETWs, it didn't work. Figuring a battery issue, we looked over the tool and could not see a battery compartment. When in doubt, RFM. The last paragraphs on the backside of the instruction sheet covers batteries. Silly us...they're inside the end of the handle. We unscrewed the cap and...no batteries.

Once we dropped in a pair of AAs, we powered-up the tool. Using the "units" key, we set the wrench to read in foot-pounds but it can also be set to read in inch-pounds and newton-meters. With the arrow keys and the "set" button, we programmed the Electronic Torque Wrench for 100-ft/lbs then used it to tighten the wheel nuts on the "Blue Bullet", the CAC's 2012 Z06 test car. 

That first time we used a GearWrench electronic torque wrench several years ago, we tightened some wheel nuts in three passes using a star pattern and, on the final pass, when we hit 100-lbs/ft., the ETW vibrated–imagine our surprise–a we neared the required torque. We thought that use of haptic technology is pretty neat and that continues with this new series of ETWs. The handle vibration is just part of a clever system of advising the user is approaching the desired torque level. Simply notification that the correct torque has been reached can result in the torque target being overshot. It's better to warn that the desired torque is being approached. Gear Wrench Electronic Torque Wrenches do both using haptic warning and beeping. There is a new feature related to how these wrenches present information: a lighted display, which we've found very handy when working in low light. The display turns red when the desired torque is reached.

The ETW programming was written such that not only can the tools be configured to alert the user that the fastener's desired torque number has been reached, but a "target torque alert" which is that warning that fastener tightness is approaching the desired level. The target torque alert is set by pushing the "%" key, using the arrow keys to select the tolerance, then saving the entry by pushing the "%" key a second time. Ten percent below the desired torque is common value to set for the torque alert. As fastener torque gets within 10% of the target, the tool makes a pulsing tone. When the desired torque is reached, not only is it shown on the display, but a red LED comes on, the tone sounds continuously and the handle vibrates.

We like the intuitive way the GearWrench Electronic Torque Wrenches advise the user of both approach and arrival at the desired torque. We like the ½-drive ETW's length, which makes torques in the 150- to 250-ft/lb. range easier to attain and we like the feel of the handle of both. 

Having ETWs in three torque ranges, is a great feature, too. Recently, we needed to install a Continental Elite drive belt on the LS7 in the Blue Bullet. It uses an aftermarket, manually adjusting belt tensioner which has a ⅜-square drive hole for an adjustment tool. You attach a torque wrench, pull on the wrench until you see 25-ft/lbs to tension the belt then tighten the lock bolt. The GearWrench ⅜-drive ETW was the right tool for that job. Once we approached then reached 25-ft/lbs we got the same haptic and aural warnings. The ¼-drive wrench has all the same features. 

That said, torque ranges is the one area were we think GearWrench didn't go far enough. The ⅜-drive and the ¼-drive tools are the same length and that makes the ¼-drive models' torque range a bit limited. The least torque it can measure is two-foot/pounds or 24-in/lb. There are some service tasks which require tightness of less than 24-in/lb. We don't understand why the ¼-drive ETW was not shorter such that it could accurately measure down to say, five-in/lbs.

Another feature we like is the addition of the 120-tooth ratchet assemblies to all three of these top-of-the-line ETWs. I like the feel of the 120-teeth and their three-degree minimum "swing" for ratcheting action. I wondered about the strength of a 120-tooth gear and inquired about that. The GearWrench folks told me that their solution was to "double-stack" the pawls such that they alternately engage the 120-tooth gears. That provides the strength of a 60-tooth ratchet with the function and feel of a 120-tooth tool. We were told that double-stacked pawls deliver 180% of ASME-standard torque performance. These ETWs also have other desirable features of GW's 120XP ratchets: low-profile head and on/off lever. Additionally, the electronic torque wrench have flex-heads which have 15-deg of travel either way. While that's less than flex-head ratchets and wrenches, with a torque wrench, flexing has to be limited so has not to noticeably affect the tool's accuracy. 

These new ETWs look good and are nicely presented. They are made of chrome-plated steel, a brushed aluminum display section and a black-anodized, knurled aluminum handle. The gleaming steel and brushed aluminum make for a, rich, high-end appearance which should please any professional or advanced DIY service technician. The GearWrench series of electronic torque wrenches with torque angle, come in black plastic cases with orange, hinged lids and snap-lock latches. When you open the case's lid, you see the wrench nestled in a sponge rubber cut-out.

Each wrench comes with instructions and an accuracy certificate. Each has a limited one-year warranty. Additionally, GearWrench ETW calibrations are warranted for 90-days.

GearWrench's Electronic Torque Wrenches are well-played.

For more information  on these ETWs, visit GearWrench's web site.