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I'm going to buy a torque wrench for some high-torque bolts in my car. I need a torque wrench to torque bolts from 130 nm (95.8 lb-ft) to 160 nm (118 lb-ft). I found some torque wrenches which support a range of 30 - 210 nm. However, I found a problem with all of them and that is the length of wrench. All torque wrenches of this range (even the most expensive ones) are about half a meter long (20 inches). Now, imagine you want to torque a particular bolt in your car to 160 nm (118 lb-ft). Torque = Force x Distance > 160 nm (16.31 kg/m) = Force x 0.50 (meter) > Force = 16.31 / 0.5 = 32.6 kg (about 72 pounds)

Do you think an average human arm can exert such a force (72 pounds) to a torque wrench handle? Why don't they make torque wrenches a bit longer? I don't think adding an extension to the wrench would be a good idea because you may damage it.

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  • We used to clamp a torque wrench into a bench vice set to 100lb/ft, then the challenge was to “click” it WITHOUT any method of bracing yourself against the bench. So 1 arm to pull and both feet on the floor - no other contact. It was fun taking the piss out of the feeble ones :)
    – Solar Mike
    Aug 23 at 5:51
  • And they do make longer torque wrenches : like 2m long - used on trucks etc.
    – Solar Mike
    Aug 23 at 5:52
  • @Solar Mike - How much force you could exert by your arm without any assistance? Can you give me an estimate? Aug 23 at 6:03
  • I gave you exactly that. Did you not read my first comment? What did you not understand?
    – Solar Mike
    Aug 23 at 6:20
  • @Solar Mike - In your first comment, you only mentioned 100 lb-ft. I don't know the length of your torque wrench to calculate kg or pounds. Aug 23 at 6:26
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I have a torque wrench of the same dimensions that you are talking about and can operate it without a problem.

While I can pick up a weights a lot heavier than 72lb (32kg), you will find that operating a torque wrench on the higher settings is not just about using your arm. You will likely hold it with both hands and use your whole body to move the wrench to give a smooth action to the movement. It may be that you keep your arms straight and use your legs to move you or you lean to pull on the wrench, but it will rarely be just your arm doing the work.

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  • I already have a smaller torque wrench (0.38 meter long and 15 - 80 nm range). I can easily apply 80 nm with it which equals 21 kg of force. Since I'm not a muscular man like you, I wanted to make sure if I can manage 32 kg of force or not! Aug 23 at 6:20
  • @NarimanAsgharian 32kg is not a force - it is a mass. Do keep track of your units…
    – Solar Mike
    Aug 23 at 6:21
  • @Solar Mike - I know it is a mass but here I'm referring to it as a force for easier explanation. Aug 23 at 6:23
  • @Nso 32kg applied at 0.5m, 1m or 2m? That is why we use the correct units.
    – Solar Mike
    Aug 23 at 6:30

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