Are Impact Wrenches Worth Buying? August 12 2022
For the first two decades I worked on my personal cars, I didn't have any air tools, like a pneumatic impact wrench or air ratchet. One of my friends was quite surprised, as I worked on my cars all the time. Most professional mechanics I've seen have impact wrenches and they are supposed to make jobs quicker and easier. I eventually got an air compressor and an impact wrench to see what all the fuss is about. Here's my experience and my opinion on whether an impact wrench deserves a place in my garage.
Impact wrenches are supposed to make quick work of getting fasteners on and off. They can loosen rusty bolts and spin them off quickly after they are loosened. And with battery improvements in recent history, impact wrenches also come in more and more powerful battery-powered versions, so you don't have to buy an air compressor or drag an air hose around like you do with a pneumatic impact wrench.
Before I had any kind of impact wrench, I would commonly use the hammer-on-wrench technique. For stubborn bolts, I would put a box-end wrench on the fastener and then whack the other end of the wrench with a dead blow hammer to get it loosened. It's quite effective, and is a lot safer on your knuckles than just pushing or pulling on the wrench as hard as you can. For really stubborn bolts, I sometimes substitute a 5 pound mini-sledge hammer, but I try to avoid it because this is hard on the wrench. Otherwise, I would use a breaker bar to break stubborn bolts free. Once loose, I'd typically use a ratchet or ratcheting wrench to spin off the nut or bolt reasonably quickly. Once free-spinning, I'd just use my fingers to spin the nut or bolt off the rest of the way.
Before getting an air compressor and an impact wrench, I bought a battery-powered impact wrench. It wasn't a game-changer, because it didn't have enough torque to loosen some of the tighter bolts. I'd estimate that about 40 pound feet was about the max it could dish out. It did have the benefit of not needing to drag an air hose around the work area. As a caveat, battery-powered impact wrenches have gotten much more powerful in the time since I bought my battery-powered impact wrench. Today's latest and greatest can dish out more torque and stay juiced longer, so take my personal experience with a grain of salt.
After getting an air compressor, I finally made the jump up to a pneumatic impact wrench. The main purpose of buying it was to zap off stubborn bolts, so I got a fairly large one with a high ugga dugga rating. I went with an Earthquake XT from Harbor Freight with a breakaway torque rating of 1700 pound feet. Here's my personal experience:
1. Even an impact wrench with a high torque rating isn't as effective as a breaker bar. I don't know why this is, when the advertised 1700 pound feet of torque from my impact wrench is way more torque than I could ever exert on my biggest 40 inch breaker bar. There have been plenty of times where the impact wrench at the maximum settings couldn't budge the fastener, but a breaker bar could loosen it with no trouble. Axle nuts come to mind as an example as a high-torque fastener that my impact wrench just couldn't budge.
2. There are a lot of situations where a big impact wrench simply can't fit to get to the fastener. My big impact wrench can only reach about 30% of the fasteners I want it to. Swivels and extensions can help, but often they are not enough to solve the access issue. Air ratchets solve some of the access issues, but also don't have nearly as much torque. Ratchets and wrenches are often still the only option when it comes to access in tight spaces.
3. Perhaps the most time-saving aspect of an impact wrench is spinning fasteners on and off quickly. Lug nuts typically need quite a few rotations to remove, so this is one of those situations where air tools can shine. There is also plenty of access to the fastener, so even the largest impact wrench can easily access the lug nut. However, the amount of time it takes to set up and put away the impact wrench can be more than the several seconds it saves on each lug nut. If you are only using the impact wrench for a handful of fasteners, it might not save you any time. If you have conveniences like a retractable air hose reel, a compressor always on standby and a spacious workspace where the air hose can run free, it may change the math.
4. An air compressor takes up space. I use my air compressor to drive my impact wrench, but also other things like nail guns, rivet guns, smoke testers and HVLP guns. If the only purpose of your air compressor is going to be to drive your impact wrench, it may be a hard to justify the floor space or cost.
5. Impact guns and compressors are noisy. Maybe you're wrenching at 2AM and don't want to wake the neighbors. Maybe it's annoying to have to grab your ear protection every time you fire up the impact gun. Maybe you don't want to solicit the attention of the neighborhood Karen. My loud compressor kicks on without warning and startles me 75% of the time. Noise has its downsides to consider.
6. People with less strength or endurance may benefit more from impact wrenches. Depending on your physical abilities, impact wrenches may be a game changer. If you frequently find your own physical strength or endurance limiting your progress, an impact wrench and air ratchet could be a game changer. Also, if you have a heavy, unrelenting workload, it could be a game changer, because you'll need every bit of help you can get.
My personal experience is that my impact wrench was not a game changer. In fact, even with easy access to an impact wrench and a compressor always on standby, I still find myself using hand tools almost all of the time. Sometimes, I'll break out the battery-powered impact wrench to spin off lug nuts loosened by a breaker bar. The setup involved with a pneumatic impact wrench makes it more work than it saves for just lug nuts. There are a limited number of fasteners that I can access with my impact wrench anyways. I'll bring it out to try to loosen stuck fasteners when other methods have failed. Sometimes the vibrations can coax the penetrating lubricant into the right places, or break up the rust. Sometimes the breaker bar doesn't have enough room to be an option. I'll also bring the pneumatic impact wrench out in certain specific situations like loosening a nut off a free-spinning shaft.
Your personal experience may differ. I live in Texas, where rust is not prevalent on cars, and I anti-seize all the things when I reassemble them. Your situation might be different. You may be working on larger vehicles with larger fasteners and roomier clearances. Maybe you often work on engines on an engine stand and have plenty of room for an impact wrench to get to work. There definitely are situations where an impact wrench can be a big convenience - I just don't encounter them very often for the things that I do.
The main takeaway is: don't let the lack of an impact wrench be a barrier to not working on your car. Hand tools are perfectly capable for nearly all situations. Some may find impact wrenches more convenient, or efficient, but they are not absolutely necessary. If you think impact wrenches will make your life easier and you have the space and funds, go ahead and get one. I personally, don't find them that much more convenient or efficient. If you don't have the space or funds for an impact wrench, the grass on the other side isn't really that much greener.