How tight is tight?
Do you still decide on that with a gut feeling or an assumption? You’re doing it all wrong. With advanced tools available on the market, you’re still doing it the 1960 way.
You guessed it right—I’m referring to a Torque Wrench.
Both over and under-tightening fasteners can cause catastrophes. You might end up damaging the thread, and the bolt might break when you hit a pothole at high speed or it might loosen up and come out of the groove—yeah, none of that sounds good.
Certain types of fasteners require tightening to a highly specific torque figure to work properly. And you can absolutely do that with a torque wrench in hand.
If you’re still unfamiliar with these bad boys, you’re in for a treat. What is a torque wrench and how does it work? We’ll cover all of it.
What is a Torque Wrench?
A torque wrench is a wrench, but a more precise one.
Used very commonly these days in every industry where machines are involved in, a torque wrench is a precision tool that ensures the fasteners are tightened to a predetermined torque value to avoid overtightening which may cause damage to the threads or under-tightening which may make a wheel come out and cause hazards.
Here’s the thing — torque is the measurement of twisting force. And every fastener should be tightened to the torque value that it’s recommended to be. But our fathers and grandfathers used to do it with their gut feeling and the assumption that yes, the nut is accurately tight now.
That, however, is not the right way to do it. With a torque wrench, one can know exactly how much torque is being put on the fastener so that he can match that with the recommended torque value for that fastener.
That’ll ensure there’s no over or under-tightening. Perfect.
What Are Torque Wrenches Used For?
A Torque Wrench has its use in almost all the industries where machines and metals are involved – including automotive, home repairs, and construction.
No matter what the industry is, tightening screws and bolts to the right extent is always recommended and required. Neither over nor under-tightening helps.
And when that’s the case, the usefulness of torque wrenches becomes apparent. Whenever you want to fasten a screw properly, you will require a torque wrench. A torque wrench is also necessary for gunsmithing, scope mounting, and firearms accurizing.
That said, it’s particularly useful when applying the right amount of torque is absolutely essential. For example, in the automotive industry, tightening the screws on the engine is a sensitive task and must be done using a torque wrench.
The same goes for the lug nuts on the tires – they’re critical too. In such sensitive cases, one must use a torque wrench.
Besides, We wrote an article about how tighten wheel lug nuts without a torque wrench.
Why Do You Need a Torque Wrench?
Oftentimes, people consider torque wrenches as a luxury that they don’t need, and fail to see why torque wrenches are so important.
It might not be a big deal in a few cases, but in others, respecting the tightening torque of a fastener is highly crucial for its proper operation. Over or under-tightening can cause hazards like we were talking about, the engine fasteners and the lug nuts on the tires.
When you’re doing major work on your engine, you absolutely need a torque wrench. If you accidentally over-tighten the cylinder-head bolts, you may face catastrophic coolant loss. If the exhaust manifold bolts are overtightened, that may crack the manifold itself.
What about over or under-tightening a lug nut on a wheel? Well, that can be catastrophic.
Too tight lug nuts could damage the rim, and worse, could break the wheel, especially when the driver hits a pothole or a bump on the road. If you fear that and end up under-tightening your lug nuts, they may come loose and cause separation of the wheel from the hub.
If none of the extremes happen, it’s still a big deal. When all the lug nuts on a tire are not tightened to the same torque specs, it’s likely to cause the tire to be minutely angled, which will cause an in and out wobble and that’ll end up hurting driving comfort (particularly on high RPMs), may cause premature wear of the tire and possibly the tie rods, ball joints, and brakes too.
That’s why we believe a torque wrench is an absolutely important investment that’s completely worth it.
Different Types of Torque Wrenches
A number of torque wrenches are available that serve a different purpose best. Let’s have a look at them:
Click wrenches are one of the most satisfying torque wrenches. They are called “clickers” because when the preset torque is reached, they make a highly satisfying “click” sound that everybody loves.
You’ll see a click wrench in almost every toolbox and it is best used for getting basic jobs done, particularly those when you have to reach a tight space in such a way that it blocks the visibility of the gauge meter, so you can’t see how much torque is being applied at that moment.
Since you can set the torque beforehand and you’ll know when it is met with a satisfying click sound, you don’t need to have your eyes on the gauge all the time, just having your ears open will do. Most of the click torque wrenches ensure +/- 4% accuracy.
They’re affordable, functional, and satisfying, making them a favorite of the most tool heads.
Electronic Torque Wrenches
These are also known as digital torque wrenches and unlike the clickers, they don’t have any moving parts but rather function depending on electronic sensors. These are a more modern and sophisticated solution and provide an advanced range of features that no other torque wrench offers for example, the memory function.
It contains a memory stick that saves readings and can upload the data to the computer for analytical purposes. Also, the accuracy is incredible. Most of the electronic torque wrenches ensure +/-2% accuracy. This makes them a great fit for HVAC, automotive, and aerospace scenarios.
You can see the fasteners as you keep putting the force on the wrench. It features a digital display where the amount of torque that is being applied is shown live in digits, making the reading so precise.
So, if you plan on applying 50 lb.-ft. of torque, you can stop exactly when the display is reading 50. They feature a beeper as well, so if you set the torque to 50, it’ll give a loud beep when you reach 50, and that way you won’t have to keep looking at the display.
This feature makes them as useful as clickers to work in tight, not visually friendly places as discussed above.
Beam Torque Wrench
Like electronic torque wrenches, beam models (known as deflection wrenches as well) also show the amount of torque being applied, live. The difference is that it shows the torque in an analog way versus digital in electronic torque wrenches.
So, it might not be as accurate as an electric model but at the same time, they’re generally pretty inexpensive compared to other types and also, they’re really easy to use. They’re are easy to maintain as well and don’t need to be calibrated. They’ll hold their accuracy forever as long as you don’t drop them severely or bend the beam.
One more distinguishing feature is that while you’re generally recommended to not use a torque wrench to loosen a fastener, you can do that with Beam models and they read in both directions.
And that’s because of its straightforward mode of operation. It doesn’t ‘click’ or ‘beep’. So there’s an extra handle over the main body of the wrench and a gauge near the main handle of the wrench.
When you apply force, the pivoting handle simply moves according to the amount of force being applied, and you can get the reading from the gauge, and stop when the handle moves enough to reach your desired torque figure – it’s that simple.
However, one issue with such a method of measurement is the angle that you look at the gauge with. If you look at them from a side off-angle, you’ll get a much different reading versus when you stare straight down.
Split Beam Torque Wrench
A Split Beam Torque Wrench belongs to the family of beam torque wrenches but operates like a Click Wrench, but better.
These are usually heavy-duty tools and can range from 100 to 800 dollars. With a “clicker wrench”, you have to twist the handle quite a lot depending on the torque setting you want to preset.
However, a split beam model makes life a little easier. There’s a knob that you have to adjust to preset your desired torque figure (shown in a gauge) and take my word for it, it’s way easier than a Clicker.
From the zero position to set a torque figure of 120 lb.-ft., if a clicker took you 15 secs and some twisting, a split beam will take you 3-5 secs and no energy.
Another advantage with this type is that you don’t have to release all the pressure to bring the torque setting to zero before storing it away like you had to do with “clickers”.
You can leave this in whatever setting you want for however long you want and the spring will not deform. In a split beam model, the spring is always under the same tension and it relies more on a lever and catch mechanism to operate.
Upon reaching the desired torque setting, it’ll make an audible, satisfying click. It’s just a more sophisticated, more expensive big boy wrench that’s usually used in a heavy-duty environment.
Slip Torque Wrench
The Slip models come in handy when you have a delicate, low-torque job in hand. These models are made for small, low-torque jobs, like the ones in the delicate electrical components.
The mechanism is in its name – slip. When the desired torque setting is reached, it’ll temporarily slip, eliminating any chance of over-tightening, and be back on afterward.
You can get low to medium duty jobs done with slip torque wrenches and use them where you need to absolutely eliminate the chances of over-tightening because since the wrench will slip, you cannot overtighten even if you wanted to.
Hydraulic Torque Wrenches
You can tell from the name that it’s used for really heavy-duty purposes. Hydraulic torque wrenches are often used in industrial settings where they reach very high tightening torques using the mechanism of hydraulics.
When both power and precision are required, you’ll need to deploy one of those bad boys. There are very minimal chances that you’ll require one of these in your household.
What Size Torque Wrench is Most Useful?
The socket drive size is the primary reference for torque wrench sizes. They come in four common drive sizes –
- 3/4 to 1-inch
Each size has its particular set of use cases. However, a crossover between sizes at times is not strictly prohibited – you could get away if you know what you’re doing.
The 1/4-inch torque wrenches are geared towards low-torque tightening jobs like working on a small motorcycle engine and so on. Oftentimes, you’ll see the markings are done in an inch-pound unit on these sized wrenches. If you need even less torque and more precision for electrical components or small fasteners on critical pulleys, you can use a 1/8-inch drive wrench.
3/8-inch models are a great fit for working on the engines of your car. However, it might often not be enough to put lug nuts on the tire, especially if you’re working on a mini truck or something even bigger.
1/2-inch is a great intersection point for all the usual jobs you need to get done. You can do cylinder heads, lug nuts, suspension bushings, and so many other things with it. You’ll find this wrench to be the most common in most toolboxes.
You pull a 3/4 to 1-inch size torque wrench out when you need to work on really larger vehicles or you need to get some other job done that demands really high torque.
If you have the budget and plan to buy only one for most household and personal car jobs, you already have an indication of which one to go for – yes, the ½-inch model. It sits on the sweetest spot and is the go-to size for most enthusiasts’ tool heads.
You can check out the ½-inch model from Lexivon—it’s phenomenal.
How To Use a Torque Wrench?
Before you put the wrench to use, you need to make sure it’s properly calibrated. It ensures that the tool is working properly and that the reading won’t be inaccurate.
Made that sure? Onto the next step – setting it to the desired value.
Now, that’s different depending on which type you’re using. For a “clicker wrench” there’ll be a lock below the handle which you need to release first. On a split beam model, that small lock is supposed to be placed towards the side of the wrench.
After releasing the lock, you need to rotate the knob on the split beam model, and the rotating handle itself on the clicker to set the wrench to your desired torque figure. Once done, lock the knob/handle.
For an electronic model, there’ll be a set button and up and down arrows that you can configure the desired torque with. And for a beam model, you don’t need to preset any torque figure, just keep looking at the dial while you’re tightening and stop when the gauge indicates the right amount of torque has been reached.
How do I know which is the right torque value? You may ask. Well, I don’t know, you know. If you’re working on your car, refer to the user manual. The ideal torque figure for each of the important fasteners should be listed there.
Working on other things which you don’t exactly have a manual on? You’ll find online forums and other websites giving you the ideal figure. You could also call an expert if you know one, just make sure you note it down and don’t keep calling for the same figure over and over again – just a piece of advice.
The next step is to put it to work. Remember, a torque wrench is not a tool to tighten all the way from zero. Use your ratchet wrench to get to a point where the fastener is giving some resistance and then put your torque wrench into action.
If that’s clear, put on the socket on the drive of your wrench and start tightening. Keep the force on until you hear a loud click on the clicker and split beam type wrench, and a beep on the digital model (also a flicker of the LED light), and stop putting force quickly. For the beam model, you already know what to do.
Congrats, you’ve tightened a nut perfectly.
A Few Maintenance Tips to Wrap It Up
- If you’re using a “Clicker”, then you need to release the pressure on the spring before you store it away, otherwise, you’ll end up reforming it if you keep repeating this that, simply bring the torque value to zero, then go a little higher to keep a little pressure running on the spring (or just keep it to zero) and lock it there. Own a split beam model? You don’t need to care about that – store it however you want.
- Regardless of the type, you don’t want to slip one of these out of your hands. They say—”a torque wrench that has fallen on the ground is no good and can’t be “ However, even if that could be a little exaggerated, it’s true that falling from a good height could ruin the calibration and could give inaccurate readings, which will ultimately ruin the whole point of a torque wrench.
- You need to calibrate a “Clicker” either every 5,000 uses or once a year. It’s a mechanical device, and there are moving parts inside, so wear and tear come into play. So, regular calibration is required to keep it accurate and properly functional.