So many people will not have a torque wrench in their toolkit because they simply don’t need it that often—maybe three to four times a year. Understandably, they don’t think it’s worth investing a hundred or even a few hundred dollars (from quality brands) in getting a torque wrench.
The story could end there, but it doesn’t. What about those one or two occasions when they just can’t help without it—like when working on a cylinder head or a spark plug?
Those are really sensitive and you’ve got to get the torque right, otherwise, you might need a repair that’s way more than a couple of hundred dollars.
We’ve got your back on such a stressful day.
Can You Measure Torque Without a Torque Wrench?
Yes, you can actually measure torque without a torque wrench, even though we aren’t sure how convenient you’ll find it to be. But the best of both worlds is not something we get every day.
All we can say is that it works, and it’s probably the best bet that you’ve got now.
However, it might not be the alternative to every case where you need a torque wrench. But it’ll work on most of them. When it needs a really high torque value, this might not be the method you want to go for.
You can be a better judge of it once you get to know the process.
Here’s How To Measure Torque Without a Torque Wrench
To get this done, you need two things—
- A breaker bar or a long ratchet that’s at least a foot long (if not, there are still way out)
- A fish or luggage scale
Wondering how it works? Or already got a clue?
Torque is nothing but the measurements of a twisting force —the force that causes an object to rotate about an axis. You can take it as the rotational equivalent of the linear force.
The unit of measurement of torque is ft-lb, which hints a lot. Simply put, the amount of force applied from a one-foot distance to make something rotate is the measurement of torque. 5 pounds of force from a foot? That’s 5 ft-lb of torque.
You should by now be getting the hold of why we recommended taking a bar that’s at least a foot long. A fish or a luggage scale? That’ll just measure the amount of force applied, so you can use anything that’ll show how much force you’re exerting.
Enough Scientific Explanation. Get Your Hands Dirty.
Measure your breaker bar or ratchet and mark it at a foot. You could use something like a tape or anything that you find convenient.
Now that’s the foot, where are your pounds? Hook up the luggage scale right on the mark and you have your DIY torque wrench ready to be deployed.
Simply hook up the ratchet to the bolt you want to get tightened and instead of applying pressure by holding onto the handle of the ratchet, hold the body of the fish scale and pull in the direction that’ll exert the force on the bolt in your desired direction.
To make it simpler, since torque wrenches are mostly used to tighten a fastener at the desired torque only, you would want to pull the scale downwards to the extent that you want the bolt tightened to the torque figure.
Just keep looking at the display of the scale while you’re exerting force. If you want 10 ft-lb of force onto the bolt, you want to stop when the scale reads 10, or as close to that as you can get.
So that’s applying 10 pounds of force to the bolt from a distance of 1 foot, which is nothing but 10 ft-lb of torque.
What if you have a shorter bar or ratchet only? You’re going to need a calculator then (or not, if you’re like really sharp with numbers).
Here’s the formula:
X = (12 / Y) * Z
X= The pound figure that the scale needs to read
Y= The length of the ratchet
Z= The desired torque figure for that particular fastener
You need to tighten a bolt to 25 ft-lb with a ratchet only 10 inches long. Here’s what the scale needs to read:
X = (12 / 10) * 25
X = 30
So hook your scale at the end of your 10-inch ratchet, and exert force until the scale reads 30. At that point, you’ve tightened the bolt to 25 ft-lb of torque.
A quick tip: When you have a 10-inch ratchet, it’ll be better to do the math with 9 inches and hook up the scale 1 inch from the end of it. Otherwise, when hooked up to the very end, it could cause accidental slips and thus hazards.
Can You Do Inch-pounds Also Following the Method Above?
Well, certainly you can, and it’s no real extra effort, just a little calculation.
Basically, if you need to measure inch-pounds without a torque wrench, that’s also possible in the above-mentioned way and it’s not that difficult either. You don’t need to reconfigure things on the side of the mechanism.
You just need to do some conversion calculations.
You probably already know that 1 foot equals 12 inches and that’s all we need to do the math.
When you need to convert foot-pounds to inch-pounds, you just need to multiply the value by 12. In the same way, when you need to go the other way, you need to divide the inch-pound figure by 12 to get the ft-lb value.
Here’s the simple formula:
Foot-pound figure * 12 = Inch-pound figure
Inch-pound figure / 12 = Foot-pound figure
You need to keep this conversion method in mind because it’ll help you in other cases as well.
10 foot-pound equals 10*12=120 inch-pounds.
And, 240 inch-pounds equals 240/12=20 foot-pounds.
So basically, to measure inch-pound without a torque wrench, you don’t need to do anything special. You need to measure it in a foot-pound figure following the method above and then just do the conversion.
So if you needed to apply 150 inch-pound of torque on a fastener, following the process explained above, you need to make sure the scale reads 150/12=12.5. That way you’ve exerted 12.5 ft-lb or 150 inch-lbs of torque on the fastener.
Can You Do It with a Digital Torque Adapter?
If you happen to have a digital torque adapter on you without having a torque wrench for some unearthly reason, you could use that to turn a ratchet into a torque wrench.
I’m putting it this way because a decent quality torque wrench could cost less than an adapter, so it makes more sense to own a wrench instead of trying to make a walkaround with an adapter.
What’s a Digital Torque Adapter?
A digital torque adapter is usually used to check the calibration of a torque wrench—to see if the readings are accurate or not. You set the wrench to your desired torque figure, put the adapter on it, and apply force to a fastener through that adapter.
As you exert force, the display on the adapter will give a reading on how much force is being applied. When your torque wrench clicks, you want to check the readings on the display of the adapter to see if it’s the same as you set the wrench on or how close.
This way you can tell if the wrench is actually clicking at the right torque or if not, how far off it is.
Following this same principle, you can easily turn a ratchet into a torque wrench. And you’ve probably already guessed how so.
Yes, this time no testing. You could simply put the adapter on a ratchet and tighten the fastener through it as you keep looking into the display. When it reaches your desired figure, you stop. It’s that simple.
There’s, however, a slightly better way to do it with most of the torque adapters. Just like a torque wrench, you could set it to beep when it reaches the desired figure. On a pretty standard adapter, there should be (+) and (-) buttons that you can use to configure the torque figure.
Now that to some extent is required because when you’re looking to torque at a higher range, you’ll have to twist the wrench pretty far, causing the display to get to an off-angle, making it hard for you to read it.
In such cases, the beep signal will let you know that you’ve reached your desired torque without having to look at the display.
What Happens When You Over or Under Tighten a Fastener?
Could you simply avoid everything, from not doing all this math to not spending dollars on a torque wrench, and get things done on the basis of your gut feeling?
You may get away on some occasions. But if you don’t, you may end up having to spend a lot more.
When you’re working on an engine, you better not do things based on your gut feeling. Over and under-tightening—both could be hazardous. Even the highly experienced mechanics having tightened hundreds and thousands of bolts would rely on a torque wrench when working on a sensitive piece.
Modern engines, with the goal of saving weight, are often made of aluminum and are very sensitive to proper torque figures. Apply too much force on them and you’ll end up causing the threads to strip, or the bolt itself might break.
If you excessively tighten a lug nut, it might break when you hit a pothole at high speed. Too loose? It could come off.
A loose spark plug could cause leaks, while an overtightened one might not function properly due to not having the proper gap as recommended.
Bottom line, you need to care about the torque figure in certain cases. When you don’t, you end up spending more than you had saved.
You Could Get Yourself a Torque Wrench for Cheaper Than You Thought
Coming up to this point, it’s pretty clear that most people occasionally working on engines and tires and other such things will not get a torque wrench just because they don’t think the hundreds of dollars they need to spend on one is worth it.
Let’s assume that’s a fair argument. What if you could get one for half a hundred dollars?
Yup, the market has a few great models that are priced at around 50 bucks, yet work pretty well. Lexivon LX184 offers a ½-inch drive model for just around $50, and it works like a charm.
Their ⅜-inch drive model is around few bucks cheaper and the 1/4-inch model is priced below 40 bucks! Whoa!
Guess what, there are even cheaper models as well, but we referred to Lexivon because we thought in the budget range, they are the most accurate wrenches. You probably shouldn’t look to go below that.
It doesn’t need saying that they won’t be as fancy and be performing in the same bracket as high-end brands like Snap-on or Dewalt, and I’m sure nobody will expect them to do so. Those wrenches cost more than a couple hundred dollars.
All I can say is they’ll get the job done surely. That’s way better than relying on your gut feeling.