What Size Impact Wrench for Automotive Work? [Lug Nuts & More]

An impact wrench is a powerful power tool that mechanics love. They widely use it for undoing or tightening of lug nuts and other applications.

Another reason mechanics love to own impact wrenches is because of their high rotational torque.

With such torque and the internal hammering mechanism, it is easy to loosen even the rusty bolts on a car.

Types of Impact Wrenches for Automotive Work

Right now, impact wrenches are widely used in the automotive world, however, not all models are ideal for automotive work.

It is why we have to look at the different types of impact wrenches to help you learn more about their possible applications.

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  Corded Impact Wrench

This type of impact wrench is electric, but you have to plug it into an electrical socket to send power to the model. Later, we will look at the cordless models.

When turned on, an electric motor in the rear of the impact wrench will drive the hammer units to produce the rotational torque required by the mechanic.

We find the impact wrench being better at speed and torque control. You can also carry such a tool around without worrying about an air compressor.

As much as a corded impact wrench is ideal for various applications, you can find them being expensive as compared to an air impact wrench. Also, it tends to overheat because of the many moving parts.

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  Cordless Impact Wrench

A cordless impact wrench is still an electrical tool only that it is powered by a battery. You will no longer need an electrical socket for it to work. For this reason, we find it is highly portable.

If you have to work in areas without electrical outlets, this is your best bet. The cordless design also makes it easy to reach into tight spaces where a corded wrench might be limited.

The biggest drawback of the cordless impact wrench should be the batteries. You need to constantly recharge them if you work on projects the whole day.

It is why some opt to buy two batteries for one impact wrench. When one battery is charging, it can keep working on the car.

The chances are that you will find the cordless impact wrench being the most expensive option. Also, it can be heavier in comparison to the corded and air impact wrenches.

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  Pneumatic Impact Wrench

Also known as an air impact wrench, this type runs on compressed air. You are likely to find such a tool in any automotive repair shop.

Since they are simple in terms of design and construction, you will find them relatively cheaper than corded or cordless models.

The biggest advantage is that the air impact wrench does not heat even when used for hours. Any heat that gets generated inside the tool is cooled by the compressed air going through the tool.

The obvious downside is that you need a source of compressed air to make it work. It might be ideal for large automotive shops, but not the best for a DIY enthusiast.

Let us say you want to work on your car at home, buying an air compressor just to use the impact wrench seems too much for most people. It is why they would switch to a cordless impact wrench.

Also, pneumatic impact wrenches do not have the best speed and torque. It is why more people are going electric to get the best performance for tough applications.

What Makes an Impact Wrench Ideal for Automotive Work?

A lot of things go into determining the impact wrench size that is ideal for automotive work. We highlight some of the factors to keep in mind when buying the right impact wrench for working on your car.

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  The Torque Figures

Nuts and bolts on your car have to be tightened correctly. It is why you need the best impact wrench that delivers enough torque for such applications.

The larger the tool, the more torque you can expect from the tool. You will also be able to tighten or loosen the nuts and bolts without cross-threading.

As much as the torque amount is important, also consider using the correct socket. It can be detrimental to use the incorrect socket as it will easily wear or break some of the internal parts of the tool.

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  Design and Size

Well, the size can also impact the overall design of a power tool such as an impact wrench.

It is not just the design, but also the handle location and many other features. A smaller wrench such as a ½-inch model would have a handle similar to a drill.

The larger ¾-inch impact wrench will have larger handles that allow for a firmer grip. A firm grip is important to allow better control of the tool’s torque.

½-inch Impact Wrenches

It is common to find such impact wrenches in an auto shop. They are loved for being compact so that you can use them in tight spaces around the car. For this size, they are perfect for working on suspensions and tire jobs.

They are likely to have a torque output of 300 ft/lbs., which is enough for handling many automotive tasks.

¾-inch impact Wrenches

For a person who needs to work on heavier equipment, then it is best to go for this bigger impact wrench. This one is mostly used by mechanics working on trucks.

The average torque for this type of impact wrench is 1200 ft/lbs. As you can see, it should have enough power to loosen and tighten the large nuts on a truck.

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  The Speed

The speed is measured in terms of revolutions per minute or RPM. Most impact wrenches will have a speed of 2,500 to 3,000 RPM.

Some will be higher depending on the design. The size can be affected by the variable speed feature.

This is because sometimes you would want the impact wrench to run at a slower speed while other times you need it to be faster. It is a nifty feature, but you will mostly find it in a drill.

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  The Weight

The size of the impact wrench will also affect the weight of the power tool.

It is expected that a larger unit will be heavier as much as it produces more power for various applications. It then comes down to the needs of a mechanic.

If you need to work on small projects around the car, then get the lightweight model.

For those who have to handle heavy-duty applications, then you will have to live with a slightly heavier model as it gets the job done.

In Summary

From the guide above, the most common sizes you will find include ½-inch and ¾-inch impact wrenches. Both are good but vary in terms of power.

Depending on the amount of work you have to do in your automotive shop, always choose based on the torque. The torque determines how easily and efficiently you can work on a task.