Sometimes an incident as simple as a punctured tire would keep you from attending the most important events of your life and you have to stay on the side of the road while the tow truck comes to pick up your vehicle, simply because you could not change the tire due to a tight lug nut and lack of the impact wrench.
An impact wrench can produce 450 ft-lbs torque. But lug nuts are tightened up to 80-100 ft-lbs. Hence Impact wrench can tighten and lose the lug nuts easily due to high torque generation. Breakaway torque is always higher than tighten torque because lug nuts can overtight, rusting, and shape deformation.
When you use an impact wrench for lug nuts, you should know torque generation, mechanism, and many more details in order to use the impact wrench more efficiently. In this guide, you can learn how to use an impact wrench with its recommended ways in detail. So keep reading on!.
How Much Torque need to Tighten Lug Nuts?
The nut lugs need specific levels of torque for them to be safely removed. 80 and 100 ft.-lbs is the torque level for most of the nut lugs. You can refer to the following torque level chart to adjust the torque to be compatible with the lug nuts of your vehicle.
| Wheel Stud Size, in inches and millimetres | Typical Range of Torque, in Foot Pounds | Number of Turns of Hardware Engagement |
| 7/16 inch | 70 to 80 | 9 |
| ½ inch | 75 to 85 | 8 |
| 9/16 inch | 135 to 145 | 8 |
| 12 x 1.5 millimeters | 70 – 80 | 6.5 |
| 12 x 1.25 millimeters | 70 – 80 | 8 |
| 14 x 1.5 millimeters | 85 to 90 | 7.5 |
| 12 x 1.25 millimeters | 85 to 90 | 9 |
How Much Torque Need to Loosen a Lug Nut?
An impact wrench with a minimum of 500 ft.-lbs is appropriate for you to remove lug nuts from your vehicle. After figuring out the size of the lug nuts you are trying to loosen, it is pretty easy to figure out the torque needed to loosen the lug nut.
The safest level to remove a lug nut using the impact wrench is to start at 80 to 100 ft.-lbs. This works if the lug nuts are well greased, regularly serviced, and maintained or new. However, if the rust or something else has tightened the lug nut, you might need to increase the torque. You can slowly increase the torque level until it gives the desired outcome. When you feel the lug nut giving in, hold steady at the current level. Increasing the torque further can break the lug nut.
Remember to use a good light source and keep an eye on the lug nuts so you will not over-torque the nuts.
Read More About – Impact Wrench Won’t Remove Lug Nut: Fixed
Why Loosening Torque is Higher than Tightening Torque?
The torque required for tightening and loosening nuts and bolts varies. It might seem impossible because the torque it took to tighten the nut is 100 ft.-lbs it should take the same amount to lose, right? However, mechanical engineers have discovered that the loosening requires less torque than the torque required for tightening.
The reason for this is that, when tightening a nut, we need it to overcome the thread friction to obtain a bolt preload. When untightening, these conditions remain the same, allowing the user to loosen the nut with less torque.
There are exceptions to this, which brings us to the answer to the question above. Corrosion, seizing, or surface roughness can increase the torque required for tightening by a considerable amount.
What Reasons Increase Loosening Torque?
As we mentioned earlier, sometimes lug nuts will not loosen due to these reasons. Here is why you would need higher torque to loosen a nut.
- Overtightening the lug nuts – When a nut is tightened more than it is required to, it can be quite tight when you try to loosen it. Over tightening can damage the nuts and the threads, making it harder as well.
- Rusting – Rust is the enemy of any mechanical item. Because the nut lugs are exposed to water, and many other compounds while driving, they can catch rust quickly. The rust prevents the nut lugs from loosening when torquing. The rust binds the nuts and the threads together in a way that makes it very hard to remove as well as it can damage the nuts when we try to remove it.
- Mechanically tight with around parts – Some components in a vehicle are sealed with other components around them. This could be both intentional and unintentional. But if the lug nuts fit together tightly with the other parts around it, it might make the torquing requirements higher than they usually are.
- Shape change – If a nut lugs shape differs from the impact wrench, the torque required for loosening the nut can increase. This could happen due to accidents, rusting, or because the lug nuts were manufactured in a different shape than the impact wrench.
What Happens When Higher Impact Wrench Torque is Used?
If you use a higher torque when loosening or tightening a lug nut, it can break because of it. Once the lug nut breaks, you might have to cut it out. Therefore, you always have to be careful when applying torque. Gradually building up to the required torque is always recommended.
How Much Torque Does a 1/2 Impact Wrench Have?
An n1/2 impact wrench usually has around 300 ft/lbs of maximum torque.
Can I Use an Impact Driver Instead of an Impact Wrench?
To loosen or tighten nut lugs, you can choose an impact driver instead of the impact wrench. However, it is not ideal to use an impact driver instead of an impact wrench.
Will a 3/8 Impact Wrench Remove Lug Nuts?
Yes, it can be used to remove lug nuts, as well as other nuts and bolts faster.
