Impact Wrench Buyers Guide – Everything you need to know about Impact Wrench

An impact wrench is a socket wrench power tool that works by storing energy in a heavy rotating mass and then releasing it all at once in small impacts against the output shaft. This puts a lot more force on the bolt or nut that you are trying to tighten or loosen. It takes a lot of the string off your wrists.

Impacts wrench or air wrench is also known by many alternative names, such as; impact gun, air gun, rattle gun, torque gun or windy gun. Now don’t get all confused with the ‘air gun’ thing, okay? It’s not the air gun you probably knew before.

These guns are commonly used in any repair, maintenance or assembly work because of the reactionless tightening and low-level noise impact. It is obvious! You can get your job done much easier than using hand tools for your fix.

Impact Wrench Buying Guide

If you are using your old beat-up electric drill, it’s time to ditch it. They are just not that good enough. What you need now is a good top of the line electric impact wrench. And, this section will guide you to pick the best one for your work.

What Is An Impact Wrench?

According to Wikipedia “An impact wrench (also known as an impactor, impact gun, air wrench, air gun, rattle gun, torque gun, windy gun) is a socket wrench power tool designed to deliver high torque output with minimal exertion by the user, by storing energy in a rotating mass, then delivering it suddenly to the output shaft.”

In any mechanical workshop or garage, you might have come across that vrip-vrip sound. That’s the sound an impact wrench makes when it is tightening screws or lug nuts. That high-pitched sound comes from high-powered impact wrench at work.

If you are a big fan of Formula-1 racing then you should definitely know what these tools are capable of. I’ve always liked how fast they unbolt the tires lug nuts with these tools.

At first glance, these wrenches look more like screw guns with some minor differences. The upper front is bulkier and comes with a special square pin. This pin is called Anvil. It is used for attaching impact sockets.

You might be wondering, why go through all the trouble of buying an impact wrench when you can use similar sockets with an electric drill?

First, the electric drill lacks power.

Second, they can even unbolt rusted fasteners.

In an impact wrench motor, not only do you have high output torque but also the rotation motion which delivers quick pulses. That’s why these tools are perfect for a workshop, car maintenance or simple repairs around the house.

Why Do You Need An Impact Wrench?

First of all, they pack a lot of punch in a small form factor. They are good for fastening bolts and tightening screws. More torque, less weight and affordable. They are also small in size which means you can carry it around all day.

These tools can also be used in furniture manufacturing and on construction sites or any place where there is a need for a quick power tool with a lot of torque. There are different types of impact wrenches with different power sources.

Why use a Battery Powered Impact Wrench?

Well, there are a large number of reasons to use this tool. I am going to mention a few of them which you cannot deny at all.

  • It can remove the bolt or fasteners very quickly that too without using a lot of muscle power or cause fatigue
  • They are more friendly and easy to use in tight working space and prevents you from the risk of busted knuckles
  • Provide you with leverage multiple time which can be generated by the manual wrench, thus efficiently removing a stuck bolt or fastener
These can be used to install or remove bolts from a number of places such as tires, frames, the engine heads and much more. Practically it has unlimited application scope. You can check out our guide about 8 Reasons Why You Should Go For A Cordless Impact Wrench

Types of Impact Wrench and Their Function

The Impact wrench comes in a variety to satisfy your needs. These discrepancies are identical in the wrench drive sizes, styles and features and functions depending on the application.

Smaller bolts and nuts adjust perfectly with the small ¼ inch wrench drive tools. Now, the ¼ inch drive wrenches are found in two structural shapes. One is the inline-type, which you can hold like a conventional screwdriver. And just like the typical screwdriver, it has the output on its end. On the other hand, the handgun like pistol grip has its output right-angled to the handle.

The 0.25-inch drive wrench is also available in an angled drive which is another form. It looks more like an online tool. However, this is equipped with a set of bevel gears that helps rotate the output to 90 degrees.

0.375-inch impacts are usually found in pistol grip forms, as the regular inline & angle drives are very rare in the market. Another peculiar form is also available, commonly known as the butterfly wrench. It is fitted with a bulky throttle paddle beside the tool. The flat throttle can be sloped to any of the sides so that you can regulate the rotation course. This allows you to choose whether you will use a separate reversing controller or not. Plus, the flat-shaped throttle has the ease of retrieving snug areas.

A bit larger, the 0.50-inch drive units arrive in pistol grip form. Whereas the inline type is getting out of the market for obvious reasons. After all, who wants a heavyweight tool with a giant handle! Another disturbing fact is its rotating force conducted back to the user himself.

Again, the essential 0.75-inch drive impact wrench exists in pistol grip form only.

When it comes to 1.0-inch drive tools, you get lucky with both the pistol grip and ‘D handle’ inline silhouette. The D handle form features an enclosed handle at the back of the tool, so you can grab a comfortable hold. Two of the forms integrate a side handle that lets you hold the tool firmly with both of your hands.

1.25 inch and larger wrenches usually come in T handle form. Each side of the tool body has large handles. As a result, the user enjoys a great control of it, thus can apply extreme torque as well.
These are the standard socket wrench drive size range for small DIY chores. Major construction works require 3½” and larger square drives.

Gigantically large impact wrenches that relate several hundred thousand foot-pounds of rotating force typically include eyeholes in their design. Since they are too big and heavy for humans to maneuver, lifts or cranes are necessary for the carriage. But these giants are not our concern. Rather they are exclusively intended for heavy-duty construction works or projects.

After all the above-mentioned crap, you have impact wrenches in these below mentioned valiant types:

  1. Pneumatic Impact Wrench
  2. Electric Impact Wrench
  3. Hydraulic Impact Wrench

1. Pneumatic Impact Wrench

Air Impact Wrenches are typically powered by compressed air. They are more of the old school impact guns. Air impact wrenches run on compressed air, so they require an air compressor to aid as its source of power.

Pneumatic wrenches can be used constantly since they do not require electric power sources. All you need is a supply of compressed air, which in fact, is not too challenging to avail. And as these are stereo-typically smaller than electric impact wrenches, you have the ease to work in condensed spaces or restricted areas.

But the bummer comes really fast! These are problematic when you have to adjust the power. Because they lack the adjustment mechanism and this makes it vulnerable to use them specifically in circumstances where you require a little torque.

The reason why air impact wrenches are less popular nowadays lies when you need the minimum torque, and uncontrolled excessive power from the pneumatic wrench causes shattering or damaging the bolts.

Check out our Top 5 Best Pneumatic impact wrench reviews

2. Electric Impact Wrench

Having the word electric in the name, it is obvious that these are powered by electricity. Now the electric impact wrench comes in corded and cordless for usability checks. In fact, the cordless featured impact wrench is most popular nowadays.

  • Corded Electric Impact Wrench

For the corded ones, you need to plug it into a power source nearby. This means corded electric impact guns are useless when you have no electric power socket around you. So these do not have the portability and convenience of the cordless wrenches.

But yet again, you can use corded electric impact wrenches as long as you want. As it runs on direct power, you do not have to rely on the batteries. These are equipped with power regulators, ensuring no regrets in cases where you have to adjust the torque.

  • Cordless Electric Impact Wrench

On the other hand, the cordless wrenches suck power from batteries, either from lithium-ion batteries or nickel-cadmium series. These batteries range up to 28 volts, starting from 18 volts as usual. These are the most common power wrenches available on the market. You may have a diversity of models within your budget range.

Consequent to the corded ones, these offer portability in remote places. You have the freedom to use them anywhere as they do not obligate any connection to a power source. These are best for people who deal with on-the-road repairs.

But none of the wrench types is an all-rounder, so the cordless impact guns also have their limitations. Running on batteries, these fail to source adequate power to produce sufficient torque for powerful chores. Having that said, these naturally are less powerful than the corded electric or air impact wrenches. Plus, you might get disturbed while your jobs to replace or charge the batteries, as the batteries drain pretty fast.

Check out our reviews about Top 10 Best Cordless Impact Wrench

3. Hydraulic Impact Wrench

These are absolutely rare and off the market. Hydraulic impact wrenches yield substantially more torque than air-powered wrenches but these are only used in heavy industrial conditions. It has such a gigantic size that instead of carrying this wrench to your job, you have to bring the job to its place.

In brief, all of the impact wrenches are exclusively advantageous for specific purposes and work spheres. Depending on the task you are to perform, one of these three will add superiority to your hands.

How Does Impact Wrench Work?

Impact wrench reviewsThe impact wrench works in a simple way. Inside your wrench, there is a motor connected to the output shaft which rotates and delivers torque impact. The motor accelerates a rotating mass or hammer that stores energy with the assistance of a spring.

There are two distinct shapes. One of those shaped like a pistol or those like a giant screwdriver. However, despite these completely different shapes both work exactly the same way.

The hammer lifts up, spins around and driven down by the spring. It is then forwarded by the drill at a much higher speed than if it were just driven by the drill directly. And because the mass hits the output shaft at a much higher speed than the drill is spinning, more energy goes into turning the screw. But this whole thing repeats twice per rotation, so the average energy remains exactly the same as what is coming out of the drill.

The hammer does not act only like a flywheel, energy gets stored in it. As well as the mass is spinning, energy gets stored in the spring too. Once the hammer gets past the far edge, the spring drives it down and spins it at the same time releasing some stored energy.

As the hammer slips past the edge of the output shaft, it rolls down a spiral cut that is in the driving shaft. This makes it slam into the output shaft and distribute all its energy in a very short period of time, putting a lot of force on the bolt or screw.

See? To sum up, you only feel the reaction force of the motor that accelerates the mass or hammer. It is the only force applied to the body of the tool. So regardless of how much torque is being delivered to the socket, you feel very little torque.

Finally, this is how the impact wrench works in three simple steps to remember:

  1. The motor begins to move the mass and output shaft.
  2. The hammer lifts spins around and hits down the driving shaft with the spring mechanism.
  3. And this goes repeatedly!

How to Maintain Your Impact Wrench

Maintenance always sounds boring as it necessitates some sort of effort out of you. But these little efforts can save a lot for you. Come on, this is the handy tool that cuts down your hard work. So you probably won’t want this handy helping hand to die too soon. To keep your Impact Wrench up and running for a longer lifespan, you ought to cling to some maintenance steps on a regular basis.

Be Serious with Sockets or Bits

While working with impact wrenches, never use such sockets and bits that are not compatible with their models. Using the right sockets is more important than it sounds. Inappropriate sockets can even cause you a loss. It can bring about breakage to the parts. And, if things go more wrong, you might face accidents and physical injuries.

Respect Your Power Tools

Yes, I know what I have just mentioned in the title. Your tool is your helping hand and being unnecessarily rough with it is not good. Like, dragging it along or dropping it to the ground from heights is ethically discouraged. Treat it well and carry it by the handle. After each workout, make sure the cords are free from wear and tear. Needless to quote, but do not approach an impact wrench that has damaged cords for the next run.

Look Before You Leap

Check all the parts before you use the impact wrench. If by chance, any of the parts appear to be damaged or if switches are not responsive, then either repair it or replace it completely. Before further use, take it to a service technician and seek assistance in fixing your tool.

Clean Your Accessories

Tidy tools always live longer and if the accessories are not clean, the tool will eventually get dirty itself. So, spare some effort to clean your impact wrench accessories. Avoid putting them in wet conditions, or open to the scorching sun. Keep them free of all kinds of debris and dirt. Because dirt plays a harmful role in any tool. It can be a headache for wedged parts.

Lubricate Moving Parts

Basic maintenance of any moving component is to keep them lubricated all the time. Moving parts of your impact wrench go through a lot of friction and heat. And to make this easy on your tool, you have to lubricate them according to the manual. And most importantly, with that specific lubricant that your impact wrench manufacturer has advised. Oil-filled motors ask for a change at regular intervals. Don’t forget to check that out. If you are using a pneumatic impact wrench, test whether the air-flow is normal or not.

Careful with the Torque

Never avoid excessive torque. Be careful while applying torque to your work. Make proper adjustments and proceed, because excessive power can cause dangerous accidents and damage your studs and accessories. Never remove the housing cover from your impact wrench while using, rather protective covers are beneficial for the added safety of your tool.

Performance Checkup

The rotating or spinning power your impact wrench is supposed to supply should be constant in both directions. Measure the torque output to get this report sometimes. If the working torque is somehow not like before, then it needs a personal touch by an expert technician. It is another essential part of the maintenance steps.

Store Them Nicely

Each and every time after using an impact gun, do a casual check. Wipe them clean in a well-ventilated area and remember not to use detergents for cleaning. Lubricate if it seems necessary. Then put them nicely organized in any enclosed storage drawer or closet when not in use.

How to Repair Impact Wrenches

Like every other tool, impact wrenches are no different than having problems to fix. It is recommended to go for a technician, but there are some common malfunctions that you can fix it your own home. This both saves your money and time. So you will never regret once you learn some basic troubleshooting for your impact wrench.

Dead or Slow!

If your impact wrench is playing all dead or running too leisurely, do a quick check. Chances are, shingles or glue have caught in your tool. Rinse your tool with any solution that eradicates glueyness. Remove all the unwanted particles and dry off. Pour lubricants in through the inlet and run the impact wrench so that all the moving components get lubricated. You are good to go!

For air impact wrenches, check if the rotor blade is okay or not. A worn-out ball bearing can also be the reason behind this sluggish movement. If so is the case, swap the worn-out stuff and try running it again. Still doesn’t work?

Make sure the air pressure is enough and there is no leak in hoses. And sometimes, multiple air hoses from compressors cause air pressure imbalance that is responsible for such a malfunction.

Moisture Dripping Out!

Now, this can happen for two reasons. If the moisture drips off your electric impact wrench, it can be the excessive amount of lube you have put on recently. Take a dry piece of cloth and suck it off as it drips or blows out of your tool. Run your wrench again and repeat this step again and again until there is no more moisture left to blow out.

If you are having this issue with a pneumatic wrench, then probably your air hose or compressor tank has water in them. Check the hose and take all the water out. Open the compressor tank, get rid of the water, and apply a little lubrication. Turn your tool on and see if more moisture is blowing out or not. If yes, repeat the process and try again.

Reduced Impacts!

This is one of the most common problems we face. The solution comes easy too. Your impact gun impacts less than before because it is either lacking lubrication or is jammed with sticky lubricant. Apply lubricant to the motor and impact mechanism. If the motor is not affected by rust or corrosion, then it should work just fine.

For sticky lubricants, use WD 40 and wipe it clean. Sticky oils make the rotor toilsome to run freely. If you have tried all of these and still it does not impact properly, set the regulator to the fullest power and watch.

Different Usage of Impact Wrench

Impact wrenches are seemingly the same as impact drivers. But in reality, they have many things uncommon. Impact drivers come with a 0.25-inch hex-shaped opening outer shaft, whereas, impact wrenches introduce a broad range of sockets with significant sizes.

Impact wrenches are commonly used for automotive or industrial jobs. May it be assembly or disassembly, construction or fitting chores, impact wrenches has the power to handle them all. Breaking lug nuts, and pulling off head nuts on studs is no more exhausting with this powerful handy tool today. You can have long stretches of time to work without any lethargy, anywhere.

The portability of newer model wrenches has made its way into the tool storage of every mechanics. Being widely used for untying lug nuts from automotive-like cars and trucks, impact guns also boasts the power to assist in any high-torque situation.

For your information, an average cordless impact wrench can lodge half-inch sockets of countless sizes, and can easily fit a wheel lug.

Conventionally impact wrenches have been air-powered tools, which are still being used in specialized garages by professionals. Luckily, in recent years, cordless impact wrenches have become far and widely available. They are armed with such a load of power that they can loosen lug nuts in a matter of seconds. You can now pull out nuts hardened at nearly a hundred feet of torque. The socket attached to the impact gun moves slowly as it begins to open the nut loose and soon as it gets loosened, the socket spins quicker till the nut comes out.

Pro Tip: Do not put excessive torque or over-torque the lug nuts for quicker tightening. This may cause stripping and stretching of the threads. Use both of your hands to hold firm pistol-type impact wrenches. If you do not hold the wrench properly, the torque reaction can give you wrist pain from injuries. Grab the handle with one hand, and keep the other grip on the top.

Impact wrenches are great for removing tires in a speedy manner yet in a convenient style. This is why the impact wrench for tires sounds effortless and quick. Fun fact is, they literally sound irritating when turned on, so don’t forget to wear ear protective safety gear while using them.

We have also covered this topic in a separate article “8 Reasons Why You Should Go For A Cordless Impact Wrench”

Safety Tips

  1. Always check your hose and connectors before using an impact wrench. If there is any sign of damage, replace it immediately. A little malfunction can lead to serious injury or accident.
  2. Don’t be a cheapskate. Buy better quality tools. Most low-cost impact wrenches are not durable enough to endure the immense stress these tools produce.
  3. These tools have a lot of torque. Make sure you fasten your socket properly. Also, hold the grip firmly or else you’ll end up with a twisted wrist.
  4. Always wear ear protection. These are some loud tools. Keep some distance between you and the tool.
  5. If you are using a pistol grip, hold it with both of your hands. One hand at the grip and another around the top, this way you will have a solid hold of your tool.
  6. Always take proper care of your tools. Don’t believe what manufacturers tell you. A little effort and care for your tool will extend the service life of these tools by a lot.

We have covered an article about “10 Essential Tips for DIY Safety” with an infographic.


1. How much torque is needed to tighten lug nuts?

The average torque to tighten a lug nut is about 8- to 90 ft-lbs.

2. How tight are you supposed to tighten lug nuts?

It is somewhere in between too tight and tight. There is a sweet spot in between. Over tightening can cause failure around the rotor.

3. Do you need to wear safety glasses?

If you don’t care about tiny metal pieces chipping off and getting into your eyes then don’t.

4. How do you start threading bolts?

Always start it by hand. After that, use your tool. It’s safer this way.

Final Words

No matter which type of impact wrench you choose to use, it adds great value to your tool works. Your time and physical energy will not get wasted working with hand tools anymore. Keeping an impact wrench boosts your overall work efficiency and saves a lot for further actions.

Leave a Comment