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Discussion Starter · #1 ·
Do you use a torque wrench to remove bolts? The lady at NAPA said never to do so, but why would they give you the option of changing the ratchet direction if you shouldn't go backwards.
 

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Aguacate said:
Do you use a torque wrench to remove bolts? The lady at NAPA said never to do so, but why would they give you the option of changing the ratchet direction if you shouldn't go backwards.
That is to torque left hand threads. She is right. If you care about your torque wrench you shouldn't do it.
 

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a torque wrench is a calibrated tool designed to measure the force with which a fastener is tightned.
using one to remove fasteners can damage the tool either breaking it or causing it to give inaccurate readings. you would not want to tighten your rear wheel nut to what you think is spec, only to have your wheel come off because your wrench is 15 ftlbs off because of misuse. likely mabey not, but it is possible. I'd hate to damage my bike or myself because i was too lazy to use the right tool for the job...
 

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I understand that, but how is using a the tool to loosen a bolt any different from using it to tighten a higher torque left hand thread?
 

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Lets not complicate this. Torque wrenches should be used only to take you through the last few LBS/FT of torque. Not to loosen bolts, crack nuts, open beer bottles, beat enemies to a pulp, unclog toilets, scratch your back, stir marguaritas, clean gutters, kill spiders, stoke the fire. Errrrr, sorry, one of these days I will break the piggy bank and get a life.
 

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howley said:
I understand that, but how is using a the tool to loosen a bolt any different from using it to tighten a higher torque left hand thread?
When a fastener is first loosened it often takes a much larger amount of "reverse" torque to break it loose. That is what will damage the wrench.
 

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Discussion Starter · #9 ·
ducpainter said:
When a fastener is first loosened it often takes a much larger amount of "reverse" torque to break it loose...
I completely agree with you, and not to argue or anything but just to understand, let's say you set the torque wrench to 100 ft-lbs. Now you go to remove a bolt. Let's say that the torque wrench removes the bolt without clicking. This means that you used less than 100 ft-lbs of torque, right? Now let's say you are at the last bit of a left-handed bolt requiring 100 ft-lbs of torque and you use the torque wrench until it clicks. In this case you've applied more torque to do what it's meant to than to loosen a bolt.


Either way I think it just makes sense to use a torque wrench as MTL-DUC has described.
 

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Aguacate said:
I completely agree with you, and not to argue or anything but just to understand, let's say you set the torque wrench to 100 ft-lbs. Now you go to remove a bolt. Let's say that the torque wrench removes the bolt without clicking. This means that you used less than 100 ft-lbs of torque, right? Now let's say you are at the last bit of a left-handed bolt requiring 100 ft-lbs of torque and you use the torque wrench until it clicks. In this case you've applied more torque to do what it's meant to than to loosen a bolt.


Either way I think it just makes sense to use a torque wrench as MTL-DUC has described.
It click so it doesn't over-torque. If you continued past that point you would damage the wrench the same way
 

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ducpainter said:
When a fastener is first loosened it often takes a much larger amount of "reverse" torque to break it loose. That is what will damage the wrench.
But if you have the wrench set to a high torque value, how is it any different to doing a left hand thread up really tight, providing you don't go past the click? I'm not saying anyone is wrong, but I need a explanation for why I can't do it.
 

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howley said:
But if you have the wrench set to a high torque value, how is it any different to doing a left hand thread up really tight, providing you don't go past the click? I'm not saying anyone is wrong, but I need a explanation for why I can't do it.
Ducpainter gave the explanation. Usually the break away torque is greater than the installation torque. You will particularly notice this on your oil screen. Add to this the electrolytic action between the fastener material and the part material and you have a problem. We won't even mention the gorilla who worked on your bike last.
 

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Yeah i see that the break away torque is much higher. But if you were to torque a left hand threaded nut up to the other nut's breakaway torque, would it then damage the wrench?
 

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howley said:
Yeah i see that the break away torque is much higher. But if you were to torque a left hand threaded nut up to the other nut's breakaway torque, would it then damage the wrench?
You won't damage the wrench if the wrench is set higher than the torque required to break the fastener loose. You cannot measure or calculate the breakaway torque. It's not worth the chance of ruining an expensive wrench.
 

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howley said:
So provided you don't torque past the click trying to undo the bolt it won't damage the wrench?
Yes.
Again, how do you tell if the fastener will break loose below the max of your wrench? Is it really worth the chance?
 

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I don't think it's just the click part that matters. Isn't the sudden give after the bolt comes loose also a factor in damaging your torque wrench? When tightenting you control how much pressure is applied and can gently push to tighten until you get your click and ease off pressure slowly. When loosening, even if you have it set to a much higher pressure than required, when the bolt breaks loose there will be some tension built up in the torque wrench that is suddenly released. Torque wrenches aren't meant to take that sudden force and that contributes to damaging the wrench as well.

Also, it hasn't been mentioned here but it seems this all regarding the fancy "click"-type torque wrenches, not the old school ones with the needle that look like a sword. ;D Even then, those ones still shouldn't be used a breaker bar even though they look alike. The shaft is meant to flex so you can tell how much pressure you're putting on while a on a breaker bar it isn't. The elastic properties of the material work best for small loads. When the bolt breaks loose the sudden release of tension acts more like an impact load and your material loses a bit of its elastic ability.
 

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pnut said:
Just use your $200 torque wrench any way you want. Let us know how it turns out.
$200? You bought a cheap one. I have the Techwrenches from Snap-On ( I used to make a living with them) The 1/2" and 3/8" IIRC they were about 600 or so each. Not saying you have to spend that much, just get a quality one from the start, and be careful not to drop it. I had someone drop my in/lb one. Cost $100 bucks to recalibrate it
 

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Discussion Starter · #20 ·
I think I paid $30 for mine. How accurate does it have to be?

I can understand if you make your living off of it...
 
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