If i were to put an extension on my torque wrench, would it alter the reading at all?

Putting an extension on the socket end should not change the reading by a noticable amount to completely throw your reading off.

Putting a piece of pipe or anything on the handle for more leverage will drastically change your reading.

Putting a piece of pipe or anything on the handle for more leverage will drastically change your reading.

Would it?

If I might ask: why?

Edit: Hang on, you may be right.

Will report back when I have read more

I've only really found one reputable source on the subject, and it agrees with timmah.

However the maths and my own logic do not agree.

For example:

1)

Get out your torque wrench and put it on a nut. Put your hand on the handle but extend your forearm out parallel to the handle. Then, use your upper arm to apply the force perpendicular to the handle to actually apply the torque (you will need to put a lot of wrist strength in to make this work). This is fundamentally exactly the same as using a breaker bar, with your forearm being the bar and your upper arm being the new forearm applying the force. And yet no-one ever says that how you position your arm matters.

2)

Imagine a ratcheting torque wrench. It is very obvious that the ratchet is going to let loose at a certain torque level, every time. It doesn't care how the fuck that torque gets there. It's just a clutch. Clutches have a torque load and that is that.

3)

If a breaker bar made a difference, then on a 30 cm torque wrench, putting your hand just say, 1 cm higher up or down the handle would also cause a 3.3% error, in exactly the same way as a breaker bar. 3cm=10% error. And hell, each person is going to be applying the actual force to the wrench with a different mix of pure force and torque, and each person will be applying it with a different part of there palm, etc. If this were the case, fuck torque wrenches.

4)

Overall, as far as I can see this should be one of those wonderful situations where torques and forces all cancel out and overall, don't give a shit if the breaker bar is there or not. But the only force I found disagrees. The only exception to my thoughts being that if the measuring device is in the handle somewhere, not the head, and you start applying force on the wrong side of it or something... that would mess it up An example being applying the force to a beam type wrench, on the wrong side of the indicator.

If your torque wrench measures torque by body flex it is possible to alter the readings. All the ones I've ever used measured torque directly at the socket either by known-distance flex or ball-give and whose readings cannot be affected by lengthening or shortening the torquing force distance.

Uh. Torque wrenches work with the torque at the nut, so if you make the lever twice as long, it will be easier to put out the same torque. And more than that torque that you set it to, and it will just click away.

Torque wrenches I believe are calibrated to measure torque depending on the length of the shaft of the wrench and where the point of pressure/leverage is applied. Adding an extra length of shaft is going to add extra leverage, and thus throwing off the calibration of the wrench because the point of leverage is at a different location.

Someone can test this by torquing two nuts the exact same point. And breaking one loose with a regular bar, and recording the amount of torque, and breaking the other loose with a bar that has extra length on it.

Then again, I may be wrong, but it's my own two cents.

I've only really found one reputable source on the subject, and it agrees with timmah.

However the maths and my own logic do not agree.

Don't ask me to explain it. It doesn't make any sense in theory to me either, but I have seen it first hand in shop class after the teacher explained it.

Don't ask me to explain it. It doesn't make any sense in theory to me either, but I have seen it first hand in shop class after the teacher explained it.

What type of torque wrench were you using?

What type of torque wrench were you using?

Indeed. I am very curious as to what this type it.

Recall that there exist some torque wrenches that measure the defection of a long outstrechted rod that simply points to the applied torque on a scale which is mounted to the body. I am very sure if you were to apply a cheater bar in the right way it would not read correctly.

Like I said, the good torque wrenches measure torque in a way that the force length of the measuring device is known. That way, adding a cheater bar will not throw off the reading. For instance, the Snap-On model I used to torque down the tire lugs on my truck has it's head separate from the body, and the body measures head flex to determine torque. Since cheater bars don't normally work on less than 1/4" the reading won't be affected.

In the end, though, if you don't understand how youyr wrench works, just keep your hand in the knurled region like the manual says. Better to be right and the task mayhaps be more difficult than take the easy way out and be wrong, right? ;)

What type of torque wrench were you using?


The older deflection style one. I am not sure what would happen with a click-style wrench.

The older deflection style one. I am not sure what would happen with a click-style wrench.

'The only exception to my thoughts being that if the measuring device is in the handle somewhere, not the head, and you start applying force on the wrong side of it or something... that would mess it up An example being applying the force to a beam type wrench, on the wrong side of the indicator.'

Could that have been the case?

Unfortunatly, not being an engineer designing these things, I don't really have an answer for that. All I know is what I was told and what I witnessed. I don't know enough about the mechanical aspect to explain it properly.

Torque wrenches I believe are calibrated to measure torque depending on the length of the shaft of the wrench and where the point of pressure/leverage is applied. Adding an extra length of shaft is going to add extra leverage, and thus throwing off the calibration of the wrench because the point of leverage is at a different location.


This man speaks the truth. Putting an extension on shouldnt alter your reading too much. Just use the shortest extension you can work with for accuracy.

Putting an extension on the socket end should not change the reading by a noticable amount to completely throw your reading off.

Putting a piece of pipe or anything on the handle for more leverage will drastically change your reading.

Putting an extension on the handle will give you greater leverage, true, but I'm pretty sure the indicator of a torsion type torque wrench will also display this greater force.
I'm a click fan myself, and you'd have to think when a certain foot/lb was reached, it would click.
The wrench doesn't know you're screwing around with its handle length.

putting an extender on the handle will do nothing to alter you torque readings. it will just require less force (due to the increase of lever length).

however, putting an extension between the torque wrench's drive (that 3/8's or 1/2 cube that you plug the sockets into) will effect the the torque reading. torque is lost to the twist of the extension. the same principal is used in "torque sticks." torque sticks are teh tools you use to tighten lug nuts with your half inch drive impact. the length, width and material of the torque stick limits the output of the gun (200+ ftlbs) to an acceptable torque for lug nuts (80 ftlbs)

putting an extender on the handle will do nothing to alter you torque readings. it will just require less force (due to the increase of lever length).

This. The same force is being applied to the wrench regardless. You won't hurt the wrenches feelings by adding leverage.

Uh. Torque wrenches work with the torque at the nut, so if you make the lever twice as long, it will be easier to put out the same torque. And more than that torque that you set it to, and it will just click away.

This is true. You won't have to use as much strength as with a shorter handle,and your reading will not change.

This is true. You won't have to use as much strength as with a shorter handle,and your reading will not change.

I'm sorry, this seems to be a serious question, but agreeing with the two above. Your not changing the "physics" nor the nature of the device in its purpose by adding length to the handle, or the socket ( unless you twist it and cant hold it perpendicular to the fastener). Try this analogy. If I put my leg up on the engine block and pull with both arms, will it read the same as if I used one hand? There you go...poetry.

I'm sorry, this seems to be a serious question, but agreeing with the two above. Your not changing the "physics" nor the nature of the device in its purpose by adding length to the handle, or the socket ( unless you twist it and cant hold it perpendicular to the fastener). Try this analogy. If I put my leg up on the engine block and pull with both arms, will it read the same as if I used one hand? There you go...poetry.

By your logic, if we have two bolts, head high. They have to be fastened to 5 nm. Now, on one bolt we use a 2 foot long torque wrench, set it to 5 nm, and pull down with one hand. On the other bolt, we set the wrench to 5 nm, and then hang from the torque wrench and pull down as hard as possible. According to what you just said, the two bolts would have different levels of fastenedness (lol). If we were using a huge wrench, maybe. But thanks to how a TW works, no mater how long the lever is, as long as 5 nm is applied, it unlocks and clicks away.

By your logic, if we have two bolts, head high. They have to be fastened to 5 nm. Now, on one bolt we use a 2 foot long torque wrench, set it to 5 nm, and pull down with one hand. On the other bolt, we set the wrench to 5 nm, and then hang from the torque wrench and pull down as hard as possible. According to what you just said, the two bolts would have different levels of fastenedness (lol). If we were using a huge wrench, maybe. But thanks to how a TW works, no mater how long the lever is, as long as 5 nm is applied, it unlocks and clicks away.

Exactly! We have a winner!

By your logic, if we have two bolts, head high. They have to be fastened to 5 nm. Now, on one bolt we use a 2 foot long torque wrench, set it to 5 nm, and pull down with one hand. On the other bolt, we set the wrench to 5 nm, and then hang from the torque wrench and pull down as hard as possible. According to what you just said, the two bolts would have different levels of fastenedness (lol). If we were using a huge wrench, maybe. But thanks to how a TW works, no mater how long the lever is, as long as 5 nm is applied, it unlocks and clicks away.

Pretty sure you just agreed with him.

Pretty sure you just agreed with him.

I was being sarcastic. They would have the same tightness.

^ actually you can over torque with a torque wrench. the click stick type will click when the desired torque is reached, but nothing is stopping the idiot using it from still pulling on it. aside from over-torquing, damage to the tool may ensue.

^ actually you can over torque with a torque wrench. the click stick type will click when the desired torque is reached, but nothing is stopping the idiot using it from still pulling on it. aside from over-torquing, damage to the tool may ensue.

Uhmm... how does one apply more torque while the wrench is ratcheting along?

^ actually you can over torque with a torque wrench. the click stick type will click when the desired torque is reached, but nothing is stopping the idiot using it from still pulling on it. aside from over-torquing, damage to the tool may ensue.

What nereth said. I'm sure there might be some that click as a warning, but the ones I used on delicate shit (torquing head studs, sealing crank case halves, etc) all ratcheted after a certain amount of torque.

the torque wrench works like a regular ratchet. you can turn clockwise or counter-clockwise (the switch is made at the head like a normal ratchet). once your desired torque is reached the handle "breaks." the handle pops over a detent. once you have popped over the detent, you can continue applying torque. i have one in 10-150 ft lbs (by matco) and one from 25 to 250 in lbs (by sk) every other decent tech i work with has 2-4 of them.

^ actually you can over torque with a torque wrench. the click stick type will click when the desired torque is reached, but nothing is stopping the idiot using it from still pulling on it. aside from over-torquing, damage to the tool may ensue.

This is why torque wrenches need recalibrated over time.

MAC does it for $20 I believe :)