Understanding Scale and Accuracy within a Automotive Click Torque Wrench

Before using an automotive click torque wrench, it’s important to understand how it works and why it works the way it does. Without that basic understanding, it’s difficult to ensure that an automotive torque wrench will be used correctly every time. Unlike many other tools, an automotive click torque wrench is a precision measurement instrument. The precision of the tool is dependent upon the proper use, care, and calibration.

To help ensure proper use, there are a few basic concepts that the end user must understand. The most important of these are the type and scale of the automotive torque wrench being used and the accuracy it provides.

True Dual Scale Torque Wrench

Types of Automotive Torque Wrenches

 

Click Torque Wrench
The most common type of automotive torque wrench is the adjustable “click” type. This wrench can be set to a desired torque value and will make an audible “click” when that torque value is reached. The handle will also briefly release, letting the user know it’s time to stop tightening.

Preset Torque Wrench
Preset torque wrenches provide a single torque value that is not user adjustable. These automotive torque wrenches are far less common, and they are typically found in production environments where the same torque value is used repeatedly.

Automotive Click Torque Wrench Scales

The scale on an automotive click torque wrench determines what range of values it can be used with and how fine the adjustments can be within that range. Some tools feature only master scale adjustments, such as foot-pounds. Others have a second micrometer scale that would allow the tool to be fine-tuned in inch-pounds.

The range of the scale limits what torque values it can provide. An automotive click torque wrench with a scale of 15 to 75 foot-pounds would not be suitable for torqueing a fastener to 100 foot-pounds. Torque wrenches have better accuracy near the middle of their adjustment range, so pushing the limits is not advised.

Automotive Click Torque Wrench Accuracy

The accuracy of an automotive click torque wrench is typically stated in terms of full scale (FS) or indicated value (IV). This can make a big difference in terms of the actual accuracy at any given torque value.

  • Full Scale Accuracy—An automotive click torque wrench that uses FS gives an error tolerance that covers the entire range of adjustment. The allowable error on a wrench of this type may only be 5% over the entire scale, but that can make a big difference depending on the set torque value. At lower settings, the torque accuracy may be reduced by as much as 50%.
  • Indicated Value Accuracy—IV provides an error tolerance for any set value. If the IV tolerance is 5%, then the tool will be accurate to within 5% of the set value, regardless of where that value falls on the adjustment range. For precision work along a wide range of torque values, IV is much more accurate.

When Precision Counts

Accurately tightening fasteners is crucial for making repairs, upgrades, or installations. An automotive click torque wrench is the preferred tool for proper tightening. However, like any tool, an automotive click torque wrench is only accurate when used properly and in the appropriate situations. Understanding how and why an automotive torque wrench works should help you choose the right tool at the right time.

Call us at 1-888-925-2763 or contact us to speak with a MountzPro representative to learn more about MountzPro’s automotive click torque wrenches.

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