How to Use a Torque Wrench

by Contributor

One of the necessary tools for the home auto mechanic is a torque wrench. If you want to follow all the manufacturer's recommendations for repairs and routine service, you will need to know how tight to tighten bolts. The torque wrench will tell you exactly how tight something is and allows you to set the wrench so that you don't over-tighten a bolt or nut.

Examine the torque wrench. You will see that the torque wrench looks very much like a standard socket wrench except that the bottom part of the handle has a dial that you can rotate to set the degree of force you want to exert on a bolt or nut as you tighten it. By rotating this dial, you can change the force limit for the wrench.

Look in the manual for your make and model of car to discover what the manufacturer's recommended "torque" is for the particular nut or bolt you are tightening.

Take the dial at the end of the wrench and change the dial by rotating it back or forward to reach the setting stated in the manual. Be sure that the torque wrench is set in the correct units for the manual that you are using. There are two standard measurement systems used to measure force. One is the metric system and the other is the U.S. Imperial system.

Find the right socket for the nut or bolt you are planning on tightening. Attach it to the wrench and fit it to the bolt or nut. Begin tightening the bolt or nut with the wrench and continue in short strokes of the wrench handle.

Stop tightening when the wrench feels like it "breaks" or slips on the nut. This is when the force being exerted on the wrench has reached the recommended amount of force. The wrench doesn't actually break or slip on the nut. There is a mechanism inside the handle of the wrench that releases the force, once it reaches the setting on the handle.

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