I have had mechanics and one person who builds competition airplanes swear that torque wrenches are inaccurate when an extension is added. To me, this flies in the face of the Action, Equal and Opposite Reaction Law. Just wondering if anyone has seen any explanation for this widely accepted phenomenon.I do quite a lot of my own maintenance to my vehicles and I consider recommended critical. I think about these claims every time I set my torque wrenches. I can see a possibility of error if a universal comes into play but with straight extensions I don't see it.

Maybe it's the potential to end up with the head of the torque wrench not directly above the bolt, particularly with a long extension. Or using your hand to support the extension adds a slight amount if drag.Edit: Either way, it's not enough to matter.

Impact gun, yesHand held torque wrench, no

Doesn't make much sense. If you have the torque wrench set at X lbs. then it doesn't matter how much the extension flexes or twists it is only going to show the lbs exerted on the wrench. You either are applying the correct torque or not!

Having spent 30 years in the missile building business, I can assure you we didn't adjust our torque values for any twisting action in an extension. Of more concern would be whether your torque wrench is properly calibrated or not. In our business, we would recalibrate torque wrenches every six months. On average 5% of them were out of the specified tolerance at this interval. How many home mechanics take their torque wrench out of the box, and never calibrate it for the life of the wrench?

I've worked on automotives for decades. Both professionally, and now, hobby wise. Have never experienced that, and don't buy it.Universals, yes. Simple extensions, no.If there is any inaccuracy, it will be minor, and likely within the margin of error of the instrument anyways.Here's an interesting article from Hot Rod Magazine about torque wrench myths and truths.http://www.hotrod.com/how-to/additional-how-to/ctrp-1111-torque-wrench-myths/Mike

Myth that socket extensions change torque wrench readings

89 Replies

BB_TX
Nomad
Jul 30, 2015
Harvard wrote:
smkettner wrote:
Impact gun, yes
Hand held torque wrench, no

X2

Correct answer.
Harvard
Explorer
Jul 30, 2015
smkettner wrote:
Impact gun, yes
Hand held torque wrench, no

X2
wnjj
Explorer II
Jul 30, 2015
Walaby wrote:
Universals, yes. Simple extensions, no.

If there is any inaccuracy, it will be minor, and likely within the margin of error of the instrument anyways.

My point was that a long extension can act slightly like a universal if the socket is not squarely on the bolt.

I agree that it's minor.
WyoTraveler
Explorer
Jul 30, 2015
I don't think the torque on the nut or bolt changes. i.e. mine clicks at the same torque. The advantage of an extension would be that I would need to apply less effort on the handle. Those 350 lb torques get harder as I get older. The longer handle helps.
Walaby
Explorer II
Jul 30, 2015
I've worked on automotives for decades. Both professionally, and now, hobby wise. Have never experienced that, and don't buy it.

Universals, yes. Simple extensions, no.

If there is any inaccuracy, it will be minor, and likely within the margin of error of the instrument anyways.

Here's an interesting article from Hot Rod Magazine about torque wrench myths and truths.

http://www.hotrod.com/how-to/additional-how-to/ctrp-1111-torque-wrench-myths/

Mike
TucsonJim
Explorer II
Jul 30, 2015
Having spent 30 years in the missile building business, I can assure you we didn't adjust our torque values for any twisting action in an extension.

Of more concern would be whether your torque wrench is properly calibrated or not. In our business, we would recalibrate torque wrenches every six months. On average 5% of them were out of the specified tolerance at this interval. How many home mechanics take their torque wrench out of the box, and never calibrate it for the life of the wrench?
MickD
Explorer
Jul 30, 2015
Doesn't make much sense. If you have the torque wrench set at X lbs. then it doesn't matter how much the extension flexes or twists it is only going to show the lbs exerted on the wrench. You either are applying the correct torque or not!
time2roll
Nomad
Jul 30, 2015
Impact gun, yes
Hand held torque wrench, no
wnjj
Explorer II
Jul 30, 2015
Maybe it's the potential to end up with the head of the torque wrench not directly above the bolt, particularly with a long extension. Or using your hand to support the extension adds a slight amount if drag.

Edit: Either way, it's not enough to matter.

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Myth that socket extensions change torque wrench readings

89 Replies

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