Torque wrenches are most often used in automotive applications, but can also be applied in tasks where a certain amount of torque is required on a bolt or nut. Knowing how these tools work and selecting the best ones for your tool chest can be a very rewarding endeavor.
The following guide is designed to help both beginner and veteran users compare different types of torque wrenches. Once you know which type you need, it becomes a simpler matter to find the best torque wrench to add to your collection.
How a Torque Wrench Works
Torque wrenches are designed to measure and apply an amount of torque. The amount varies based upon the length of the handle and amount of force being applied. These wrenches use one of two systems (calibrated spring system or deflection beam) to detect how much torque is being applied and reflects this on a meter or dial.
Torque is measured in feet per pound (ft-lb) in imperial or Newton-meters (Nm) in metric. The desired amount can generally be set using a mechanism built into the handle. In a typical click type wrench, the mechanism produces an audible click when the proper torque has been reached. The maximum setting for a torque wrench is usually 200 or 250 foot-pounds.
Torque Wrench Types
While in itself it’s a type of wrench, there are actually four main types of torque wrenches available, each of which has its own pros and cons. Balancing these qualities to best fit your personal needs is an important part of proper tool selection.
#1 – Click Type
Perhaps the most popular type of torque wrench out there, a click-style is so named because it produces and audible click when the desired amount of torque is reached. This makes them incredibly easy to use.
Modern click wrenches are cheap and pretty much just as accurate as a beam-style wrench, making them a great choice for all skill levels. A mechatronic torque wrench is a modern variant which also provides a digital display reading.
The downsides to this type of torque wrench are important to note. The click doesn’t prevent over-tightening, as you can still turn the wrench afterwards. Being able to stop as soon as you hear the click will minimize the amount of over-torquing but takes good motor control.
#2 – Beam Type
This peculiar-looking wrench uses a long beam attached to the head as a plumb line, as well as a scale on the handle beneath it. This handle is designed to flex slightly as the amount of torque increases, causing the scale to shift under the pointer. Reading the tool is similar to using a regular weight scale, with the position of the pointer on the scale indicating the amount of torque currently applied.
Beam-style torque wrenches are simplest in design and use physics to give highly accurate readings. They require the least amount of maintenance and tend to have the longest lifespan. For this reason, they are commonly used to help calibrate other tools.
Unfortunately, they can be more difficult to read and far less convenient than modern click-style wrenches, making them a poor choice for beginners. Note that a modern variation of the beam type is the aptly-named dial type. This version uses a gauge-style dial to indicate the torque and is much easier to use due to the simpler display.
#3 – Digital Type
Pre-calibrated for a more accurate reading, digital torque wrenches are an excellent choice when you want convenience and efficiency. Many models allow you to preset multiple torque settings or are able to retain a setting over multiple uses.
Once you reach your target torque measurement (or secondary pre-measurement alert), the wrench will notify you with either a buzz, beep, vibration, or light (or all of the above). Most digital torque wrenches have a good notification system so you don’t go past your target torque setting.
Unfortunately, these are the most expensive variation of a torque wrench, making them less attractive to the average DIYer. Additionally, they require batteries and some models require you to zero out the setting or may lose calibration over time, requiring you to reset them occasionally to regain accuracy.
#4 – Slip Type
Simple yet effective, a slip-style wrench is designed to lose grip when the desired torque is attained. This has the benefit of eliminating over-torquing risks while allowing for a cheap and durable tool. The teeth in its head dictate what torque the slip point will occur.
Unfortunately, you cannot monitor the current torque with this type of tool, and they rarely handle a torque over 100 Nm, making therm a poor choice for high-torque applications. For this reason, slip-style torque wrenches are often overlooked when shopping for automotive tools.
While technically not a torque wrench, adding a torque stick to an impact wrench, whether a cordless impact wrench or pneumatic (air-powered) model, essentially turns it into one. This combo is commonly used in tire, alignment, and auto repair shops to make quick work of tightening a high amount of lug nuts to the desired torque setting.
Since torque stick sets come in predetermined torques specifying the amount of flex each stick will give, you may need to do the final tightening with a torque wrench to get to exact specs. While this combo might be overkill for a home garage, it’s great for someone who needs speed and consistency such as a commercial setting.
Note that air impact wrenches need an air compressor while battery powered impact guns may lose accuracy at higher torques. Using impact sockets is necessary when using an impact wrench.
There are other types of torque wrench which are designed for more specific tasks, such as the no-hub wrench (used in plumbing) and hydraulic torque wrench (highly specialized for use in aviation). These and electronic variations of the aforementioned main types are far less likely to wind up in your tool kit and thus are not specifically covered here.
Common Torque Wrench Sizes
The size of your torque wrench can have a major effect on what it can be used for. Occasionally, there is a bit of overlap in functionality between two sizes, but each drive size is generally reserved for specific tasks.
This is the smallest common drive size. You will most often need these for small aluminum gas motors. Thus, this is a great choice for motorcycles, mopeds, and the like.
A 1/4-inch drive will also come in handy for small electronic devices encountered in some HVAC applications. You will also use these for valve covers and other very small automotive fasteners.
This is the smallest drive size you will likely use for major automotive repair. It is most often needed for engine work, such as tightening spark plugs. While this is the most common type of drive size for socket sets, it’s the second most common as far as torque wrenches go.
When discussing torque wrenches, this is the default drive size. It is ideal for installing lug nuts and working on vehicle suspension. If you currently don’t have a torque wrench, you’re probably using a lug wrench or tire iron when you need to remove the lug nuts on your vehicle.
3/4 to 1-Inch
You likely won’t need anything this big unless you’re working with a semi or construction vehicle. One-inch drives are often paired with breaker bars for especially tough truck lug nuts.
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- Torque Sticks – Why You’d Want Them (and Best Models)
- 6 of the Best Cordless Impact Wrenches for the Money