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Torque wrenches, while straightforward in concept, require much different use and care compared to a regular ratchet. This can be confusing to someone who has never used one before. There are several answers to be found on SE but it requires a lot of searching for specific queries.

This question is focused on mechanical "click-type" torque wrenches as they seem the most likely type to be used by a home mechanic.

I'm looking for standard practices on:

  1. Proper use of a torque wrench which prevents damage to both the wrench and the object being wrenched upon;

  2. Proper care of a torque wrench which will ensure a long usable life (including maintenance and storage procedures, e.g., storing at lowest setting).

  • Since nothing has really changed since starting the bounty, I will be letting this bounty expire without award. – Dan A. Jul 12 '16 at 19:38
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The main things I've always heard/done.

Always unwind before storing. This helps to keep stress off the springs. If you leave it wound up, the springs can get weak and give inaccurate torque readings.

Don't go past the click. Once it clicks, don't turn it further. Can't remember why you shouldn't do this (aside from over-torquing).

I always try to use as few extensions as possible. Not sure if it matters.

Always use the right torque wrench for the job.
<25ft/lb - 1/4"
25-75 ft/lb - 3/8"
75 - 150ft/lb - 1/2"
150lb+ - 3/4"

  • +1 This is pretty much it. Store with the tension unloaded, and go slowly enough you can back off as soon as it clicks. Wrenches will be least accurate at the ends of their range, so choose a size that has your torque value as near the middle as possible – thunder2709 Jun 10 '16 at 21:14
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    Calibrate once in a while. The more you calibrate the less you need worry about releasing spring tension. Frequency of calibration is a matter of debate and personal choice, but I don't think the answer is "always unwind and never calibrate" ... As far as "use", it's ONE smooth slow stroke until click. Done. No check clicks plus some angel's share torque... – SteveRacer Jun 11 '16 at 12:07
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If you have a "Deflecting Beam" torque wrench, they are designed to be uses only for tightening. DO NOT use it to undo a thread. Otherwise the wrench will need to be re-calibrated.

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  • Interesting, why's that? Some "deflecting beam" wrenches are "dual", why would it hurt the wrench to use the other side of the scale? use-enco.com/ProductImages/0045383-24.jpg – I have no idea what I'm doing Jun 13 '16 at 7:34
  • @IhavenoideawhatI'mdoing: Is there a reason why you'd want to use a torque wrench specifically in order to loosen a bolt? I can't think of one; I'd rather loosen the bolt and then re-tighten with the torque wrench. – Ellesedil Jul 5 '16 at 19:00
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    @Ellesedil: Sometimes you want to measure breakaway torque. This can tell you if a fastener has started to loosen due to vibration, or was over-torqued and the bolt/stud may have stretched or weakened. It can also show that someone used an impact gun instead of a torque wrench to install your lug nuts. – TMN Jul 5 '16 at 19:14
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    @Ellesedil some bolts are reverse threaded, sometimes the torque wrench is the closest tool with a long elbow. It doesn't really matter, the question is theoretical, why not use it in reverse if it has a scale on there? – I have no idea what I'm doing Jul 7 '16 at 8:50

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