If you’ve ever changed a car tire, you know that one of the biggest concerns is tightening the lug nuts. You don’t want to overtighten them, so it doesn’t damage the lug thread, and neither do you want to under tighten them, so the wheel doesn’t come off in motion. How do you then determine the turning force to use during lug nut tightening?

This is where torque comes in. Torque is simply the turning force you use when you tighten a bolt, nut, or screw. The right amount of torque determines if your parts will stay together, come apart, or break.

When it comes to mechanical assemblies like cars, many of their parts’ manufacturers recommend specific torque ranges. To ensure you adhere to these guidelines, you should use a torque wrench, which has a calibrated measure to guide your tightening.

Beyond mechanics, torque and tightening help to keep things safe and secure in everyday usage, whether you’re building furniture or using power tools.

What is torque, and why should you care?

As mentioned earlier, torque is just the amount of force you use to twist or rotate something. Think of opening a jar, turning a doorknob, or tightening a screw. The more force you use, the more torque you’re applying.

For instance, if you are assembling a workstation desk, you must ensure you precisely tighten the fasteners—tools used to hold two objects like screws, nuts, bolts, and nails. If the fasteners are too loose, the workstation desk can come apart, damage the devices on it, and harm the user.

If they’re also too tight, it can break the desk’s parts or damage its fastener’s threads. Ruined threads create imperfections that can allow corrosive substances to damage your fasteners. To ensure the safety and longevity of your belongings, always consider applying the right torque in your assemblies.

OEM Torque Specifications

OEM, which means Original Equipment Manufacturer, is the exact tightness instructions recommended by the manufacturers of your car or machine for bolts, screws, and nuts. You can refer to them as the default official tightening settings.

Following the OEM torque specifications helps protect your stripped threads and fasteners, keeps your parts securely together, and maintains the structural integrity of your car. They’re useful for parts like the spark plug, brake caliper bolt, and wheel lug nut.

You can find the OEM torque specifications in the owner’s manual, factory service manual, at dealerships, in repair software, or on online auto forums.

Types of Torque Wrenches

1. Beam Wrench

   Torque Range	Typically 0–150 ft-lbs.
   Calibration Needs	Rarely requires calibration; simple mechanical design maintains accuracy over time.
   Cost	From $20–$50
   Ideal For	Basic automotive tasks, DIY projects, and light use where high precision isn’t critical.

   

   A beam wrench is like a weigh scale but for tightening. It’s a simple type of torque wrench used to tighten bolts and nuts precisely. The pointer or lever arm moves along a numbered scale as you tighten. The number it points to indicates the current torque you’ve applied.

   Unlike other torque wrenches, the beam wrench does not have a click sound to indicate the correct number. It requires you to look directly at it to get an accurate reading. However, it is beginner-friendly, cheap, and durable, making it a good addition to your toolbox.

   You can purchase it at local stores like Milwaukee Tools, online stores, or at a local mechanic shop.

2. Click Wrench

   Torque Range	Around 10–250 ft-lbs.
   Calibration Needs	Requires annual calibration or after significant use to maintain accuracy.
   Cost	From $20–$50
   Ideal For	General engine work, automotive repairs, tightening lug nuts and maintenance tasks requiring specific torque.

   

   A click wrench, just like its name, makes a click sound when it reaches the right torque. The required level of torque can be preset on it and requires a manual reading. It is made of durable metal and has a protection mechanism against over-stretching and breaking.

   The click wrench is affordable and incredibly versatile, making it a common tool in small mechanic shops and general home use. It’s also easy to use, even for a beginner.

   However, the click wrench is slow as it takes longer to read compared to digital wrenches. Therefore, it may not be ideal for automobile shops with a high volume of customers and a large workload.

3. Electronic torque wrench

   Torque Range	Varies: 3.7–37 ft-lbs. (5–50 Nm)
   Calibration Needs	Requires regular calibration as sensitive electronic components necessitate periodic checks.
   Cost	From $100–$400
   Ideal For	Professional automotive work, precision assembly, and tasks demanding exact torque readings.

   

   An electronic torque wrench, also known as a digital torque wrench, is used to accurately measure and display torque. If you’re tightening a bolt on a bicycle, it measures the torque of the bolt and displays the exact reading on a digital screen.

   It’s a very precise torque wrench that allows you to set a target torque. It gives a beep, vibration, or light flash feedback when you hit the desired number. The device’s programmable torsion rod features a strain gauge that sends signals to the transducer.

   Another advantage it has is its built-in memory, which can store readings for future reference or auditing.

4. Mechatronic torque wrench

   Torque Range	Based on model and application, 5 to 300 Nm
   Calibration Needs	Requires regular calibration needed as it combines mechanical and electronic systems.
   Cost	Based on model, from $10 to around $4500
   Ideal For	Industrial applications, quality control, and environments requiring data logging.

   

   A mechatronic torque wrench combines the features of a click-type wrench with the latest electronic technology, including error proofreading functionalities. It can troubleshoot faults during work, which enhances the quality of your connections. You can set its reading preference to either digital or mechanical format.

   The wrench has a focus controller function that gives you more control over connection joints. It’s compact, which means it can reach joints that are inaccessible to a standard wrench.

5. Hydraulic torque wrench

   Torque Range	Ranges 2,000–20,000 Nm
   Calibration Needs	Requires specialized calibration equipment.
   Requires specialized calibration equipment.	From $1,100 to over $2,300
   Ideal For	Heavy-duty industrial tasks, such as pipeline assembly, heavy machinery maintenance, and construction.

   

   A hydraulic torch wrench uses hydraulic pressure (liquid power) to tighten or loosen large, heavy-duty bolts, the kind you’ll find on airplanes, bridges, oil rigs, or construction cranes. It’s not a regular garage tool, as it is for industrial-level torque tightening.

   The wrench connects to a hydraulic pump and applies strong, controlled torque to a bolt when you press a button. It is for very accurate tightening that may require measuring down to the decimal point.

   You’ll find it in use in industries like construction, aerospace, and marine work. It often comes as part of a hydraulic system kit. You’ll require special training to operate it safely.

Can I use an extension on a torque wrench?

Yes, you can. However, you must understand how it affects the torque reading. If the extension is parallel to the torque wrench’s handle (parallel), it won’t affect the reading.

When you add an extension like a crowfoot to a torque wrench, the torque applied to the fastener increases as the lever arm extends. The calculator will determine the value you should set in the wrench to achieve the required torque of the fastener.

What should I do if my torque wrench gets dropped?

If you drop your torque wrench, inspect it for accuracy and external damage. Then, recalibrate it and test for functionality. Finally, reach out to the torque wrench manufacturer if you require further advice on the issue.

What are the key criteria for a torque wrench?

Torque head opening size must be within tight tolerance to mechanically fit the connector nut. For example, a standard head opening size for SMA nuts is 8.04mm(min) – 8.16mm(max). For 19mm N-type nuts, the opening size is 19.15mm(min) -19.35mm(max). However, note that there are also N-type connectors with 18mm or 20mm nuts.

What is the difference between torque and horsepower?

Torque quantifies a vehicle’s engines tuning force ability. Horsepower shows how fast the engine can perform. So, high torque makes an engine accelerate faster from a stop, while high horsepower makes for a higher top speed.