Impact Wrench vs. Breaker Bar

Impact wrenches and breaker bars do the same job; however, they cannot always be used interchangeably. There are some important considerations to make before using them.

In this article, I will explain the key differences, when to use them, and share my professional experience so that you can determine when and why it is best to use one or the other.

Impact Wrench vs. Breaker Bar Comparison

Key Takeaways

• An impact wrench and a breaker bar are both used primarily to remove frozen fasteners, rusted bolts, lug nuts, etc.
• The breaker bar works on the principle of a simple lever, whereas the impact wrench is a power tool that delivers a series of hammering blows in addition to the rotational force.
• When trying to remove stubborn lug nuts, an impact wrench is a safer option since the use of an extra-long breaker bar might cause the wheel stud to break.

Impact Wrench

An impact wrench is a power tool with a square shaft anvil that is driven by either compressed air or an electric motor. It has an internal hammering mechanism that delivers hammer blows in the rotational direction.

Whether air-powered or electric, impact wrenches are regarded as the modern version of breaker bars. They are meant to serve the same purpose; fitting and unfitting screws, nuts, and bolts.

Impact wrench makes the job effortless as it basically requires you to press a trigger and hold the power tool firmly until the job is done.

Pros

• They do the hard work for you.
• Fast acceleration.
• High rotational speed.
• They hammer the piece once or twice per revolution (depending on the tool’s make and model), helping to loosen stubborn fasteners.
• They can be used in tight spaces without affecting the torque output.

Cons

• Noisy. You definitely need ear protection when working continuously.
• They are expensive compared to breaker bars.
• They need external power to operate.
• Portability is an issue unless you get the cordless version which is more expensive.
• Poor or no output torque regulation.
• Depending on the type, they might need regular maintenance.

Breaker Bar

A breaker bar is a simple hand tool that works on the principle of a first class lever. This is the traditional tool used to adjust and remove fasteners like bolts and nuts. The longer the bar, the greater the torque output.

In our school physics class, we learned that the Torque = Force x Distance to the fulcrum. The following simplified equation will give you the output torque of a breaker bar.

T = rFSinθ

where T stands for torque, r is the distance from the pivot point (in this case, the length of the handle), F is the force applied to the tool, and θ is the angle at which force is applied.

From this equation, it’s also easy to tell that with a longer bar, you don’t need to apply as much force as with a shorter bar. You can also see that output torque is maximum when force is applied perpendicular to the handle (Sin 90° = 1).

Pros

• They don’t need external power sources to operate.
• They are simple and don’t require maintenance.
• You can intuitively apply more or less force to regulate the output torque.
• Silent
• Affordable. As manual tool, they are way cheaper. But I strongly recommend investing in a quality breaker bar because the ones made of poor-quality steel can break during operation and such failures can cause serious injuries.

Cons

• They aren’t suitable to be used in tight spaces.
• You have to apply force manually.
• They are much slower than impact wrenches.

Will an Impact Wrench Break a Bolt?

Loosening

Breaker bars have earned a bad reputation because, with a strong and long enough bar, it’s possible to apply too much torque (over 2,000 lbs-ft) to a stuck, rusted, and/or frozen lug nut.

On the other hand, impact wrenches don’t have as much power, with an average of 300-450 lbs-ft of torque. It relies on the hammering mechanism instead of extreme output torque, and thanks to their percussive action, they can safely break loose most stuck fasteners. It’s less likely to damage, round, crack, or warp a bolt using an impact wrench than a breaker bar.

However, suppose the tool is powerful enough, and the bolt has been excessively tightened, which makes it prone to damage. In that case, it’s still possible to break it using an impact wrench, so it’s important to be careful and use your common sense while doing this job.

Tightening

On the contrary, you can easily over-torque and damage nuts and bolts using an impact wrench when tightening. This is because they are fast, and you don’t have feedback about how much force you apply; you just have to squeeze the trigger.

In this case, the safer choice is using a breaker bar; when properly used, you won’t have a chance of doing any harm

Ideally, you should use an impact wrench or impact driver to put the lug nuts back quickly (but do not tighten it yet) and use a properly calibrated torque wrench to tighten the lug nuts.

There is one last important thing to consider to prevent breaking a bolt as you loosen or tighten it; the force applied to the bolt should be even and only in the direction the bolt rotates. When using a breaker bar, it’s easy to accidentally apply lateral and perpendicular force along with the rotational force causing undesired stress to the fastener and the threads, increasing the risk of breaking the wheel stud.

In contrast, if you use the right socket length and hold it right, using an impact wrench will always apply force in the right direction, minimizing the risk of doing any harm.

Breaker Bar or Impact Wrench?

Bearing all the above in mind and based on my own experience, I recommend using an impact wrench for removing fasteners and installing them in two stages; using an impact wrench to pull up the fastener and using a torque wrench to make the final adjustments, or a breaker bar when you don’t need as much precision.

Below you will find a list of jobs and which tools are the best to do them properly and to minimize the risks of damaging a fastener, stretching the threads, and avoiding using too much or too little torque.

LUG NUTS

The safest way to work with lug nuts is to use an impact wrench with a proper impact socket to remove them.

When assembling the tire back, you can use an impact wrench to give the lug nuts the first turns, but make the final adjustment by hand using a tire wrench or a torque wrench to prevent over-torquing or under-torquing them.

CONTROL ARM BOLT

You can use either a breaker bar or an impact wrench to undo the control arm bolt. I find an impact wrench more comfortable to work underneath vehicles, mainly when dealing with stubborn bolts.

Most control arms, not to say all, should be fully fastened when the vehicle is on the ground, resting on its suspension. Fully adjusting them while the vehicle is jacked or hung on the lift is prejudicial for the bushing. Besides, control arms shouldn’t be over-tightened; that’s why they should be fastened using a torque wrench.

REMOVING THE FAN FROM THE CLUTCH

Most fans need a special tool to dismount them while they are installed. For engines with enough space to work, you can use a breaker bar if you have enough space. An impact wrench won’t do any harm to the clutch, so use it when you work in tight spaces.

The same applies when working with the fan and clutch outside the vehicle. In the case of fans with multiple nuts, you can remove them manually with a ratchet socket wrench.

REPLACING SERPENTINE BELT

To replace a serpentine belt on modern cars, you just have to rotate the automatic tensioner in the right direction to take the tension out of the belt and be able to loosen it. This is easily done using a breaker bar.

In case you have to replace the tensioner roller or other rollers, or if you have to remove the drive pulley located at the tip of the crankshaft, a breaker bar is also the right tool to do the job. All the rollers and the drive pulley (no matter if it has one big bolt or many small bolts) need to be torqued properly, so they should be reinstalled using a torque wrench.

OTHER ENGINE AND TRANSMISSION WORK

I prefer using a breaker bar to remove parts like flywheels, cylinder heads, and other sensitive parts.

When it’s time for reassembly, I always torque these parts according to the manufacturer’s specifications using a proper torque wrench.

Steering and Suspension Work

Impact wrenches are great for quickly disassembling steering and suspension components. To fit parts that don’t require a specific torque, impact wrenches are also great to give the nuts and bolts their first twists, but it’s always best to make the final adjustments by hand, using a breaker bar for big components and a good ratchet socket wrench for medium to small parts.

Is an impact wrench better than a breaker bar?

If you ask me which one is stronger, a large-size breaker bar is definitely stronger. However, it is not always better.

An impact wrench will do some jobs more easily and faster than a breaker bar, but they are complementary tools. Impact wrenches are great when you need to do things fast or to apply brute force without using your muscles. Continuous hammer blows are often more effective than brute force, especially where the fastener is prone to breakage.

However, as you don’t feel the force, you will need a manual tool like a breaker bar or a torque wrench when it’s time to fasten things up.

Besides, some jobs can be done quickly if you combine both tools; for example, assembling the lug nuts. Finally, neither of them is better than the other, they are just slightly different, and both deserve a place inside your toolbox.