How to Choose a Torque Wrench? Practical Tips

A torque wrench is an indispensable tool for many repairs. It is also an essential component during assembly, where precise torque is crucial. Choosing the right torque wrench can determine the effectiveness and safety of your work. Find out what you can do to choose the right wrench and what to look for.

What is a torque wrench used for?

A torque wrench is a tool used to achieve precise tightening torque on threaded connections with the appropriate force, tailored to the type of material and its strength. This prevents over-tightening or under-tightening of the bolt.

Using a torque wrench is essential when joining aluminum components together or combining aluminum and steel parts, such as in the case of an engine cylinder head. Improper tightening of the cylinder head can lead to damage to the gasket, the cylinder head, or even the entire engine block. A torque wrench is also useful for tightening plastic bolts and nuts used to connect delicate plastic components inside the vehicle, engine covers, etc. For plastic bolts and nuts, it is recommended to use a torque wrench with a low torque setting.

Tire repair is another area where torque wrenches are frequently used. After using an impact wrench, it is recommended to manually tighten the bolts on each wheel to the appropriate torque.

What are the different types of torque wrenches?

Various types of torque wrenches are available on the market:

• Dial-type torque wrench: this is one of the most classic and simple measuring tools. It is equipped with a special dial above the handle, which has a scale showing torque values. When tightening, as the bolt offers resistance, the pointer on the wrench begins to move, allowing you to read on the scale the force currently being applied. Some models feature a mechanism that locks the wrench once the set torque is reached. The main advantage of this design is its low cost and reliability in use. High-quality wrenches of this type are characterized by an accuracy of approximately 4%.
• Mechanical torque wrench: This is one of the most common types of torque wrenches found in workshops of various specializations. Such wrenches are capable of tightening bolted joints with a torque range of 20 to 200 Nm. They are often called click wrenches because of the characteristic "click" sound heard when the set tightening force is exceeded.
• Torque wrench with a breakaway mechanism: this is a tool equipped with a special hinge. When tightening a bolt with such a wrench and it reaches the set value, the front part of the tool will snap back by about 20 degrees. This noticeable signal indicates that the target value has been reached. After removing the wrench, it returns to its standard position.
• Electronic torque wrench: This tool is gaining increasing popularity. Its key advantages are high precision and ease of use. Wrenches with an accuracy ranging from 0.5% to 4% are available on the market. Additionally, they may feature practical functions such as a settings memory or the ability to integrate with a computer. Wrenches of this type are equipped with an LCD screen from which current settings can be read.
  Torque measurement is performed using a strain gauge connected to a torsion bar. If the set torque value is exceeded, this is signaled by an audible alert or by the ratchet locking.

What are the sizes of torque wrenches?

Before choosing the right torque wrench for your workshop, assess your needs—primarily the torque range you will be using.

A torque wrench with a range of approximately 40 to 200 Nm is best suited for tightening car wheels, while a wrench with a torque of around 30 Nm can be used for engine work. On the other hand, for tightening spark plugs and other delicate components, it is advisable to use a torque wrench that generates lower torques, e.g., in the range of 0 to 20 Nm.

Torque values for tightening bolts in various vehicles are usually listed in special manuals describing specific car models.
The size of the socket head is also important. You must decide whether to choose a torque wrench in 1/2, 3/8, or 1/4 inch size, depending on your needs and the type of work you will be performing.

How do you set a torque wrench correctly?

Properly setting the torque wrench is essential to achieve the desired tightening torque. Therefore, before use, make sure it is properly calibrated and set to the correct tightening torque.

Check and maintain the wrench regularly to preserve its accuracy and performance. Furthermore, the torque wrench should be used in accordance with the manufacturer’s recommendations while following all safety instructions.