Last updated on February 27th, 2021 at 11:57 am
If you work on cars or any other machinery where you have to tighten nuts and bolts such as those found in car suspensions, the engine, wheels and even breaks, knowing how to use a torque wrench is very essential.
Talking about torque, it’s the force that rotates an object about an axis or about a circular part. So when you rotate a nut or bolt to tighten or loosen it, you’re applying torque to the nuts and bolts.
When you rotate them to an extent, it starts getting harder to rotate and at a point, it stops rotating. That means it has reached its maximum torque. Rotating it further than that extents damages the thread, or worse can even break the bolt.
That’s why nuts and bolts can be over tightened or under-tightened. Over-tightening wears down the thread and gets it damaged. Under-tightening it is risky, just as in car tires, the nuts can come loose if they’re not tightened properly. That’s is why having a torque wrench is very important.
It allows you to tighten nuts and bolts to their specific torque ratings. Each nut and bolt have its specific torque rating you should not exceed.
Tightening the nut or bolt over that torque rating can damage them. Using a torque wrench, you can be able to avoid that situation, and tighten the nuts and bolts to their specific ratings or specifications from the manufacturer, so they don’t come lose or get damaged unintentionally.
Types of Torque Wrench
There’re different types of torque wrenches you may encounter. They include:
Dual-signal deflecting beam
No-hub torque wrench
Among the different types of torque wrenches listed above, the click type is the most common.
So, I’m going to show you how to use it during your next project.
Related: 23 Types Of Wrenches And Their Uses
How To Use A Torque Wrench
Say you have a flat tire and you want to change your car’s wheel, the following steps will show you how to use a torque wrench to tighten the lug nuts when you put in the spare wheel, so you don’t over-tighten or under-tighten them.
In this example, I’m going to be using the click torque wrench to explain the process because it’s the most common one you’re going to find around.
Step 1: Know The Torque Specs Of The Lug Nuts
First step is to know the torque specifications of the nuts and bolts you’re trying to tighten down. To know that, check the service manual of the vehicle you have.
Inside the service manual, you’re going to find the basic procedure to repair the vehicle part you’re trying to repair, and you’re also going to find the torque specs or ratings of each nut and bolt you’re going to tighten.
Now, say you’re trying to replace the wheel of your car, then you should check your service manual and see the torque specs of the lug nuts holding the wheel.
The lug nuts in most wheels are tightened down to a 100 lb-ft of torque. Once you know the torque specs, it’s time to grab your torque wrench.
Step 2: Get The Correct Torque Wrench Size
Get the correct size of torque wrench. There’re 3 main sizes of torque wrenches you’re going to find, which include the ¼ inch drive, the 3/8 inch drive and the ½ inch drive torque wrenches.
If you’re working on cars, most of the time, you’re going to be using the ½ inch drive. Since you’re trying to change the wheels, you need to grab the ½ inch drive wrench.
Step 3: Adjust The Wrench
Adjust the torque wrench to the torque specs of the lug nuts, which is 100 lb-ft. To do that, loosen the little adjustment knob at the back of the wrench so the handle can be free to rotate and move back and forth.
Once the handle rotates freely, rotate the handle until the 0 inscribed on the handle lines up with the 100 lb-ft line on the bar.
If you want 101 lb-ft of torque, rotate the handle forward until the 1 mark on the rotating handle just exceeds the 100 lb-ft line. If it’s 102 lb-ft, rotate it forward again, clockwise until the 2 mark on the rotating handle just exceeds the 100 lb-ft line on the bar.
If you want 99, rotate the handle anti-clockwise downwards one click down from the 100 lb-ft line on the bar, so the 9 mark on the handle lines up just before the 100 lb-ft line.
That’s how to adjust a click torque wrench.
Now, since we’re tightening the lug nut to a 100 lb-ft, we have to line up the 0 mark on the handle with the 100 lb-ft mark on the bar.
Once it’s all lined up, tighten the adjustment knob at the back of the wrench so the handle doesn’t rotate and the torque doesn’t change when you’re trying to tighten down the lug nut.
Step 4: Tighten The Lug Nuts
After you’ve adjusted the torque wrench to your desired torque, it’s time to tighten the lug nuts.
To do this, get your socket, insert it in the torque wrench, put it in the lug nut, and start tightening clockwise until you hear a click.
The click sound means you’ve reached your desired torque. So you have to stop tightening that lug nut and move on to the next.
Tighten the rest of the nuts just the same way.
Once you’re through, you can stow away your torque wrench, with the peace of mind that your lug nuts are tighten to the correct torque spec. So, you don’t have to worry whether you’ve over-tightened them or under-tightened them.