Luckily, the tools you will find on market do not have a torque adjustment feature except a very few ones like Milwaukee 2769-22 which is recently launched and has torque adjustment. But I will explain how that is possible later in the article.
Before you find an answer to how to adjust torque on a cordless impact wrench, you need to understand how an impact wrench works and why there are no torque controls on an impact wrench. We will also discuss a few very cool ways to limit an impact wrench’s output torque.
How to adjust torque on an impact wrench? You can adjust torque on an impact wrench by using attachments. The most common and in-expensive way is using torque sticks, and they can very accurately adjust the end torque. You can also use dynamic torque limiters, which are very complex but are extremely precise. For air impact wrenches, you can also use air regulators to adjust output torque to some extent.
On the newer models of Milwaukee tools, you can adjust the output torque with help of a button. Here is how it’s done.
Depending on your use case, you can use different methods to adjust the output torque, and I will discuss them in detail. But let’s dive into the reason behind no torque control on an impact wrench.
Why impact wrenches don’t have adjustable torque?
You may be wondering why there is no setting in an impact wrench to adjust its torque.
The answer to this question lies in the fundamental design philosophy of an impact wrench. An impact wrench is like a hammer (The direction of hammering is rotational).
The output torque of an impact wrench is the maximum power it can hit the nuts. I will repeat this: The output torque is not the maximum torque it can provide; it is the power of the stroke it gives.
Imagine you are hitting a wrench’s end using a hammer to tighten up a nut. If you keep doing this, despite the hit being too soft, it will infinitely keep tightening the nut, although, after some time, the change will be almost impossible to measure.
An impact wrench automates this same process; hence the end torque is not the goal. It is just making the hitting process more compact, quick, and precise. That is why there is no torque setting in an impact wrench.
Is Higher or Lower Tightening Torque a problem?
Higher torques for nuts and bolts can damage its threads or can break the bolt itself. High Torques also result in complex maintenance once you need to open them again.
Lower torques can be a safety hazard, and the equipment’s actual functionality can fail due to loose nuts. You need to understand the lower and upper limits concerning your application.
Another essential thing to understand is the difference between over-tight and properly tight nuts. If you must tighten a screw at 100 ft-lb and tight it to 150, the additional 50 won’t create any issues.
How to control torque on an air impact wrench?
Ok, before I start discussing torque control on cordless impact wrenches, let’s discuss how to control torque on air impact wrenches, as you have a little more control over the output torque than electric ones.
You can control torque on an air impact wrench by using an air regulator. The air regulator can be attached to the end pressure line or the impact wrench.
Just adjust the air regulator to achieve the required output torque. However, the air regulator will only change the strike’s intensity, and it won’t precisely tighten the nuts to the required torque.
You will have to use the same methods as for the cordless impact wrench to limit the output torque. The techniques are discussed below.
Methods you can use to limit the Torque
The good news is, that we have got multiple tools and attachments which we can use to limit the tightening torque of nuts and bolts.
Again, I will repeat that we are not controlling the impact wrench’s output torque; instead, we are managing the tightening torque.
Using Torque Sticks to Limit Impact Wrench Torque
Using torque sticks to limit impact wrench torque is the most popular method.
Using a torque stick is a plug-play process. Just attach the female end with your impact wrench and connect the nut drivers on the male end.
Identifying a torque stick is very easy as the rated value is directly written on it. The thicker the diameter of a torque stick, the higher the torque rated limiting value.
How does a torque stick work?
A torque stick dampens the circular impacts (twisting) above the rated ft-lb torque value of the Stick.
The Stick is used as an extension and will work as a regular attachment till the nut reaches the rated tightening torque of the Stick. Thicker torque Sticks are hard to twist; hence they are rated for higher fastening torque.
Also, note that a torque stick will not work with a drill driver or manual rachet as it only dampens the impact for a fraction of a millimeter.
You also need to understand that the torque sticks will not yield correct results if you are using an impact wrench that has lower torque output.
For example, this will not work if the wrench’s max output torque is 100 ft-in and you are using a stick rated at 150 ft-in.
Similarly, if your impact wrench is powerful or the trigger is pressed for higher speeds, the dampening can cross the max circular deformation it can bear and either snap or keep tightening the lug nuts.
You can get a set of torque sticks for 50-100 dollars. These are pretty inexpensive and very popular.
Using Torque Limiter or Adapters with an Impact Wrench
Dynamic Torque Limiters are more complex and expensive devices utilizing clutches and complex mechanisms to limit the end torque. They are hard to calibrate but are precise torque limiters used with regular, impact, air, and traditional hand drivers.
Using a dynamic torque limiter is easy. You have to connect it between the nut driver socket and your tool. However, calibrating an active torque limiter might need additional equipment. You can also find torque limiters rated for a specific value, and they are pre-calibrated.
These adapters and limiters can cost you around 50-400 dollars, depending on the quality you are aiming to buy. Industrial Grade adapters are pretty expensive.
How does the Milwaukee 2769 Limit the output Torque?
Ok, so on one hand, I am saying that it’s not possible for impact wrenches to stop at a certain output torque, and on the other hand, we have this Milwaukee 2769 which can provide a certain level of output torque?
The answer to it lies in the last paragraph you just went through. These impact wrenches from Milwaukee have the Electonic Dynamic Torque Limiter built-in. It will sense the output torque and will stop delivering more power after a certain level.
It’s a complex piece of equipment, which will need calibration and is not mechanically based. If the sensors somehow fail, they will stop working.
I am not saying it will break, but what I mean to say is, that it is not like the tightening torque adjustment we have in screwdrivers and drills.
So, it’s a great initiative from Milwaukee and we hope other companies will also integrate this intelligent electronic chips and sensors to enhance impact wrenches capability to limit the output torque.
Manually Adjusting the Torque on Impact Wrench
If you are out of luck and don’t have any limiter or adapter, you can use a few other methods to adjust the ent tightening torque.
Method 1 – Experience: The first method is experience-based. If you know your impact wrench and have worked with it a lot, you can very precisely tighten the nuts and bolts without using any limiter. Luckily, this is the most common method used by professionals. Using your instinct, they know it. As I mentioned earlier, a few ft-lb additional tightening torque is not an issue.
Method 2 – Using Manual Torque Wrench: This method involves additional time and effort. If the tightening torque is essential, you can use a manual torque wrench to finish the job. You have to use your impact wrench at a low speed and barely tight the nuts. Once done with all nuts, use a manual torque wrench to rotate the last thread.
Method 3 – Using the speed switch to your advantage: This method advances the first method. All good impact wrenches come with a speed switch. The speed control can help you gain control of your impact wrench and estimate the end torque quite successfully.
My Favourite Cordless Impact Drivers & Wrenches
I have compiled a list of impact wrenches and drivers you can select concerning your usage. You can check them here: Best Cordless Impact Drivers and Wrenches.
So, in summary, impact wrenches have no torque adjustment feature, and you will have to use additional adapters to adjust the tightening torque of your nuts and bolts.
Overtight and under-tight lug nuts can be a safety hazard when you are driving along the highway. This not only keeps you in danger, but it can also be fatal for other people moving along with you.