Have you ever wondered what the difference between a $20 and a $200 torque wrench really is? Are the more expensive wrenches more accurate than the cheaper ones? Well, we’d like to know, too. So we’ve gathered up some examples to check with our Intercomp Digital Torque Wrench Tester and see how their accuracy compares to one another. So, come with us as we find out.

If you watched the LS5.0 short-block assembly video, you know that we like to check the calibration of our tools before we use them. But to have faith in those checks, we need to know that the checker itself is calibrated. We went over this in our Tool of the Month article on the Intercomp Digital Torque Wrench Tester.

At the factory, the tester is calibrated using a dead-weight method, which uses NIST-certified weights, hung from a fixed-length arm to calibrate the strain gauges in the tester. That calibration certificate is included with the tester, and the unit’s calibration can be recertified at the factory in the future. Our tester is within calibration, which is significantly more accurate than the advertised ranges of the tools we’ll be testing, so the Intercomp tester has our complete trust in this test.

We’ll be using one of the calibration sheets we drew up to record our tests at various torque values. We’ll then compare actual differences between wrenches along with where each wrench falls within the advertised tolerance range. For all of the wrenches in this test, they are advertised as +/- 4 percent, so the actual amount of variance allowed changes as the target torque value changes. Being 2 lb-ft off-target is out of spec at 25 lb-ft, but solidly within spec at 100 lb-ft.

The dead-weight calibration method uses a fixed-length arm an NIST-certified weights hanging from that arm for an extremely precise calibration method used on the Intercomp Digital Torque Wrench Tester.

Testing Click-Type Torque Wrenches

The first step in this test is to bolt our tester to a stable base. For us, that’s our workbench that we’ve sunk machine screw adapters into. This allows us to drop 1/4-20 machine screws through the Intercomp unit’s mounting holes and screw it down directly to the workbench. For the test, we’ll be aiming at four target torque values and testing each wrench five times at each value. We’ll then average those five values and convert them to a percentage.

The first wrench going on the tester is the Craftsman CMMT99434. This is a 1/2-inch-drive 20-250 lb-ft wrench that retails for about $100, but we got it on sale at Lowes for $59. I mostly use it to tighten crank bolts, because of all the leverage it provides. It’s a micrometer-type click wrench, which feels nice and sturdy in use. The results at all four test ranges were within the advertised four percent, with the actual variances being 0.4 lb-ft at 35 lb-ft, 1.2 lb-ft at 60 lb-ft, 2.0 lb fr at 80 lb-ft and 4.0 lb-ft at 100 lb-ft.

Next up is a newer Pittsburgh Pro 1/2-inch-drive torque wrench, model number 62431. This one actually replaced a bad-out-of-the-box wrench in a pinch a few years ago. It has a noticeably different feel to it when it clicks — feeling almost hollow. Its lack of consistency is what hurts its scores, with only the 80 pound-foot test falling within the advertised four-percent tolerance. The average variances were 1.6 lb-ft at 35 lb-ft, 3.2 lb-ft at 60 lb-ft, 1.8 lb-ft at 80 lb-ft, and 5.6 lb-ft at 100 lb-ft, with a worrying 112 lb-ft pull in the mix. To be fair, the wrench cost $9.

Then, we have another Pittsburgh Pro, but this time an older 3/8-inch-drive model. As it’s a 3/8-drive, its torque range is slightly lower than the rest of the half-inch-drive wrenches in the test. This wrench genuinely feels nice to use, and the numbers show a surprisingly impressive result. At 25 lb-ft it only varied 0.2 lb-ft. At 35 lb-ft, it again only varied 0.2 lb-ft. At 50 lb-ft, it was off another 0.2 lb-ft. At 70 lb-ft, it had its highest average variance, at 1.0 lb-ft. I’d trust this wrench on any project, with results like these.

The final micrometer click-style torque wrench we’re testing is the oldest one I have in the shop. Another $9 Pittsburgh wrench, I’ve had it in my toolbox for more than 15 years, but, because of the brand I’ve never fully trusted it for more than wheels, or things with huge tolerances. After this test, I feel like I owe it an apology. In the first test, the average deviation was 0.8 lb-ft. At 60 lb-ft the average deviation was only 0.2 lb-ft. at 80 lb-ft the average was 0.4 percent, and at 100 lb-ft it showed a perfect 100 lb-ft average, with one 101 lb-ft pull and one 99 lb-ft pull in addition to the three dead-on 100 lb-ft pulls.

Testing Digital Torque Wrenches

Now we’re moving from clicks to digital. First up is the Pittsburgh Pro 68283 half-inch digital torque adapter. It fits between a half-inch drive ratchet or breaker bar and a half-inch drive socket. This thing was cheap, but it seems to punch way above its weight class as far as accuracy. I do have to say though, it’s kind of a pain to use. It is hard to see while using it, and resetting to zero takes a significant amount of time.

But, if you want digital accuracy and don’t want to spend a lot of money, this might be the answer for you. Except that this exact model has been discontinued. In the 35 lb-ft test, its average deviation was 0.74 lb-ft. At 60 lb-ft, it had an average variance of 1.0 lb-ft. At 80 lb-ft, it only varied 0.28 lb-ft on average. At 100 lb-ft, the average variance was only 0.52 lb-ft, with no single test more than 0.9 lb-ft off of the target torque.

Finally, we have my main workhorse when it comes to engine assembly — the Eastwood half-inch Digital Electronic Torque-Angle wrench. This wrench was the first time I spent decent money on a wrench at around $175, and it has never let me down. It’s easy to use, accurate, and it has a decent amount of length to help make those big pulls a little easier. Unfortunately, like the Pittsburgh Pro torque adapter, this wrench is discontinued.

One thing to note in the results of this test is that the average deviation of this wrench at 35 lb-ft is only 1.52 lb-ft, but that number exceeds four percent. To that end, you probably shouldn’t be using a half-inch torque wrench for 35 lb-ft, but I’ll need to keep that in mind going forward. At 60 lb-ft, the average deviation was 1.48 lb-ft. At 80 lb-ft, it was 1.06 lb-ft, and at the 100 lb-ft setting, it was 0.52 lb-ft off.

What Do These Tests Mean?

You might think all of this is overkill, but it’s important enough that ARP actually uses this torque wrench tester on its event trailers, where you can have them check your wrench(es) for you by simply bringing them to the trailer at the event. That’s not a gimmick to get you to their trailer, but a service they feel is important to offer their customers, because the results of an inaccurate torque wrench can be catastrophic. “Torque wrench calibration is absolutely critical,” says ARP’s Chris Raschke. “We’ve seen up to a 49-percent drift on wrenches brought to our event trailer. That can really play havoc on your desired clamp load.”

As you can see, these wrenches run the gamut from cheapest to decently priced. We have micrometer-style click wrenches, digital wrenches, and even digital adapters here today. We haven’t managed to add any split-beam torque wrenches to the collection yet, but they are coming for sure.

So, while the prices are all over the place in this test, I think the result should make you feel OK about using a cheaper wrench, while still proving that spending more does tend to get you a nicer tool. “Over the years, we’ve seen that the brand of wrenches doesn’t necessarily correlate to accuracy,” says Raschke. Where the differences seem to lie, are in the features and ease of use of the tool. While the very inexpensive digital torque adapter has results quite similar to our Eastwood digital torque wrench, the Eastwood wrench is far easier to use and has more features than the Pittsburgh torque adapter.

ARP’s tester is available at any event where their trailer is, and they will test your torque wrench(es) for you. They know how critical proper fastener torque and want to make sure your fasteners are being set properly.

However, we have to point out, that the Pittsburgh Pro wrench that was outside of the tolerance range, replaced another of the same wrench, that killed a rearend housing stud on us. Maybe it was just a bad batch, but you probably won’t find a bad batch of Snap-On torque wrenches making it to customers. As an interesting aside, the out-of tolerance wrench has a completely different feel to it than the two Pittsburgh click wrenches that were well within spec.

At the end of the day, you have to trust your measuring tools, specifically, your torque wrenches. To do that, you need to verify their calibration. Sure, a lot of tools come with calibration certificates from the factory, but tools don’t always hold their calibrations forever, especially with hard use. If you’re using a torque wrench daily, you should probably have a tester of your own. “We’ve seen that many of the professional teams have their own checking device at the shop and some even in their race trailers,” says Raschke. “Besides just having a tester, it also helps to have the personnel that use the wrench to practice on the tester. Speed and smoothness all come into play for accurate results.”

Besides having your own tester, you can, at the very least, send your wrenches out to be calibrated on an annual basis. Or, if either of those options seems like too much effort or expense, you can stop by ARP’s trailer at the next event you’re at and have them check your wrench for you. It’s a little extra peace of mind to know that your fasteners are actually torqued where you want them. Your engine’s longevity depends on it.