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Impact Driver Showdown: Flex 24V FX1371 Vs. DeWalt 20V DCF887

The FLEX impact driver, with a more compact size, higher speed, and greater torque, outperformed the DeWalt model in all aspects except weight and price
July 09, 2024

Clint DeBoer from ProToolReviews has two top-of-the-line impact drivers for a head-to-head tool test–The DeWalt DCF 887 and the FLEX FX1371. Considering specs, features, and data from real-world testing, he gives the winning model a check mark for each test and tallies the results at the end of the video.

The impact driver spec sheet

Let's start with how these two models stack up regarding specs. Clint used fully charged 5-amp-hour standard batteries for both of these impact drivers during testing. Measuring from tip to tail using a digital caliper, the head length of the FLEX impact driver clocks in at 4.6 inches, and the DeWalt comes in a little bit longer at 5.3 inches. The point for a more compact size is awarded to FLEX.

Scoring each impact driver on the scale highlights one of FLEX's few weaknesses: it is one of the heavier models in its class. The FLEX weighs just under 5 pounds. DeWalt easily takes the point for weight here, with a working weight of just 3.4 pounds.

Clint tested no-load speed using a tachometer, and FLEX gets their second point here, running around 3915 RPM. This was over 600 RPM faster than the DeWalt impact driver, which maxed out at 3285 RPM.

Next, their torque was tested in the lag bolt simulation. Based on manufacturer claims, the FLEX's max torque is 2500 inch-pounds, and DeWalt trails by a large margin at 1825 inch-pounds, putting another point on the board for FLEX.

So, after looking at the specs, FLEX holds a three-to-one lead.

Real-world performance tests

We’re about to enter the next testing phase using custom rigs. Clint pushes these tools to their limits to see if their measurements match the specs printed on the box. He ran three performance tests to see what these impact drivers can do with a standard battery.

FLEX impact driver shines under medium load test

The first is a medium load test, driving a 6-inch by quarter-inch GRK RSS screw into a stacked OSB subfloor. The result is the average of three tests.

As you can see, it wasn't particularly close, with the FLEX impact driver finishing all three screws in less than 10 seconds for an average of 8.7 seconds per drive. DeWalt finished each test on the other side of that 10-second mark, with an average drive time of 12.6 seconds.

Both impact drivers struggle with sinking lag bolts

The second test is time for 30 seconds to see how far each model can drive a 10-inch by half-inch lag screw into the same stacked OSB subfloor material. The deepest drive takes the point for this test.

Neither the FLEX nor the DeWalt could completely sink the lag bolt after 30 seconds of trigger time. However, FLEX proved its superior power, leaving only a bit more than 2-3/4 inches  of lag bolt exposed, with DeWalt showing almost 3-1/2 inches of its lag bolt – and the point goes to FLEX.

FLEX breaks loose lug nuts with ease

The third and final test is designed to see how long it takes to break loose a nut that is set to 150 foot pounds – that’s 1800 inch pounds.

This simulates what you might encounter when using a tool like this to break off each of the lug nuts on a larger truck and yes, Clint recommends an impact wrench for that job but this is still a good way to test real-world torque. The result is the total time added together for five bolts.

Well, that was fast! Clint slows down the video to 50 percent so there is a little more time to see what's going on here.

As you can see, FLEX dominated the bolt breaker simulation, breaking all five bolts in a total of just 3.19 seconds. It finished the test in less than half of DeWalt's final time of 6.64 seconds. So, the FX 1371 takes the win in all three of our hands-on tests. 

Pricing and warranty

Before dishing out the final scores, Clint also looks at two more important areas that affect the purchasing decision - price and warranty.

The FLEX impact driver is available at Acme Tools and Lowe's. You can get it for $159 as a bare tool and $249 as a kit with that 5-amp hour battery and a 2.5-amp hour compact battery pack to shave off some of the weight.

The DeWalt DCF887 can also be found at Acme Tools and Lowe's. Its bare tool price is actually $10 cheaper than FLEX's at $149. The kit is significantly cheaper, with a $199 price tag for the impact driver and two 2-amp-hour batteries. Even though you don't get a 5-amp-hour battery with this kit, Clint still believes it’s fair to give the point for the price to DeWalt.

However, the shoe is on the other foot regarding warranty. DeWalt offers a three-year limited warranty, and FLEX, through the end of 2023, is offering a lifetime warranty on all of their tools, batteries, and chargers, provided you register within 30 days of purchase. That is a big win for FLEX in the warranties category.

So, which is the best impact driver?

Well, with the final tally of seven to two, FLEX definitely wins this impact driver head-to-head challenge. Whether you're a FLEX guy or you're a DeWalt guy, you're going to have strong feelings about either brand. We hope this review helped you decide which one suits your needs best.

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