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Do you lose torque through a straight extension?

Do you lose torque through a straight extension?

  • Yes

    Votes: 13 54.2%

  • No

    Votes: 11 45.8%
  • Total voters
    24
T0pwater

T0pwater

New member
Okay, I've been doing a lot of internet searching and I was surprised at how big a split there is on this question:

Do you lose torque when tightening a bolt or nut using a straight extension?

A lot of people say something like this: You should add X ft-lbs for each 6" when using a torque wrench with an extension. The reasoning is that you lose torque in twisting the extension. A lot of people say you don't lose any.

I'm really curious what you all think. Please throw back a reply and give your justification, or just participate in the poll.

EDIT: For the sake of simplicity, for the poll I'm asking about tightening a bolt with a torque wrench, and whether I'd need to increase the setting on my torque wrench if I slap an extension on there. But feel free to throw in your thoughts about the same question applied to an impact.
 
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Re: Poll: Do you lose torque through a straight extension?

you definitely lose some torque because of the connection points.
 
Re: Poll: Do you lose torque through a straight extension?

Torque = force x distance. Plain and simple.
 
Re: Poll: Do you lose torque through a straight extension?

if you stack extensions you for sure lose torque, but if you use one straight one you would lose a little torque still. but not as bad as stacked ones
 
Re: Poll: Do you lose torque through a straight extension?

Bio248 said:
you definitely lose some torque because of the connection points.
Click to expand...
I think I know what you mean but can you clarify? Are you talking about losses due to the "looseness" of the connections, that cause angles? If so, let's say for the sake of argument that we have a perfectly straight line from the head of the wrench to the fastener. They all pivot on the exact same axis.
 
Re: Poll: Do you lose torque through a straight extension?

well, i guess it also differs with how you're using it.

are we just using a ratchet or are we using an impact?
 


Re: Poll: Do you lose torque through a straight extension?

want a physics diagram to prove that you do?

example...im taking box bolts off of a chevy duramax, my impact has 1050lbs of breakaway torque..it struggles when i have a 6in extension on it taking an 18mm bolt off, when i remove the extension it doesnt struggle at and it zips the same bolt off on the opposite side much easier.
 
Re: Poll: Do you lose torque through a straight extension?

The only reason you'd lose torque is if by the extension you end up tilting the extension because you would then be decreasing the distance from your hand to the bolt. However, it would be very slight.
 
Re: Poll: Do you lose torque through a straight extension?

Bio248 said:
well, i guess it also differs with how you're using it.

are we just using a ratchet or are we using an impact?
Click to expand...

Torque wrench. Almost no motion, just at the end when it's about to click.
 
Re: Poll: Do you lose torque through a straight extension?

if you keep the pivot point constant, I don't think you lose torque. Because I recall torque being the force times the lever arm. No where does it account for the distance from the item being torqued..

might be wrong, I haven't done physics in a while lol
 


Re: Poll: Do you lose torque through a straight extension?

redlinepontiac said:
want a physics diagram to prove that you do?

example...im taking box bolts off of a chevy duramax, my impact has 1050lbs of breakaway torque..it struggles when i have a 6in extension on it taking an 18mm bolt off, when i remove the extension it doesnt struggle at and it zips the same bolt off on the opposite side much easier.
Click to expand...

Ok... edited original post to clarify. I'm talking when using a torque wrench. In the case of an impact, the situation is much more complicated - but I'd agree, from experience the answer when using an impact is yes - you do lose some effectiveness of the tool.
 
ZR1vette09 stated it correct, T= Force x Distance, it is the only formula to use, the amount of extension will not effect the T applied to the fastener, as long as it is centerd on the fastener.
 
That's in a perfect world where the extension it'self has no twist.

Torque sticks are the perfect example. They twist and only allow so much torque to be applied because of this twisting motion. Any flex or twisting of the extension (even though it's not visibly noticable) will cause decrease in the amount of torque delivered.
 
benner said:
That's in a perfect world where the extension it'self has no twist.

Torque sticks are the perfect example. They twist and only allow so much torque to be applied because of this twisting motion. Any flex or twisting of the extension (even though it's not visibly noticable) will cause decrease in the amount of torque delivered.
Click to expand...
Torque sticks are for impact guns though.
 
You definitely lose torque with an extension.

Just yesterday I was doing a timing belt service on a 3000GT and had one bolt that was refusing to come out. I had an extension on the ratchet because the short socket wasnt long enough to get inside the pulley.

After pissing with it for a minute we found a deep well socket (wasn't at my house so I was stuck using the owners tools) and it came loose with little to no effort.
 


You DO NOT lose torque because of an extension. I spent literally this entire semester going through this exact kind of problem in my mechanics of materials class.

By "lose torque" you mean that you exert X ft*lb of torque on one side, whereas the bolt only experiences Y ft*lb where X<Y. But according to statics, the sum of the forces about the rod must equal zero. So, if there is X going clockwise, and Y going counterclockwise, with no other moments being applied, then X must equal Y.

Edit: What some of you may think of as "losing torque" may actually just be your thoughts that you must be twisting the extension, which is absolutely correct. You do twist the shaft because of the equation theta= Torque * radius of the shaft / (J*G). where Theta is the angle of twist in radians. Regardless of the twist, you still have the same amount of torque on both sides. The only difference is that you must turn the wrench farther in order to compensate for the twist of the shaft.
 
If you dont loose torque then why can I take a bolt off with my impact with no extension but with an extension I cant?>riddle me that.
 
extensions don't fit perfectly.

So assuming perfect fit, I can see math saying no loss.

But they never do fit just perfectly.
 
To anyone that believes you don't lose torque due to an extension: Please test what you are saying. There is a certain amount of give in an extension. The relation and importance depends on what you are working with. Want a semi scientific test, use 4 feet of extension to take out or put in the backwards trans bolt. There is a lot of flex in that length and it is noticable. A very stubborn bolt may visibly show a twist in the extensions.

OP, if you search on Google etc for the scientific truth about this, you will find that all extensions are prone to a bit of reduction in torque. If your question is .. do you need to worry about using a 6" extension when torquing LIM or SC bolts, then no. The change in overall torque change isn't enough to make it necessary to be a concern in our application.
 
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