Torque wrenches and drive extensions.

[McRat]

Well, there is always the Chevy vs. Ford debates.
And Torque vs. HP.

But the latest is Drive Extensions on Torque Wrenches.
I was taught, and so have many others, that putting on drive extensions on a torque wrench changes the value, most agree it torques the bolt less.
Others claim that extensions have no effect, which according to physics, and in a perfect world, would be correct.

What say you?

[Jonny Hotnuts]

So many things could affect this......

An extension could allow the wrench to sit off axis in relation to the nut, how much PSI you were torqing the nut, length and quality of the extension.......

I suppose if you had a very thin, inexpensive, 12" or longer extension on a 80 psi bolt you could be off a pound or two due to twist in the extension.

[sheribuchta]

the torque wrench should apply the same torque to the nut regardless of the extension ---if anyone would like i will do an experiment and find out ---im betting it wont matter    willie buchta

[sheribuchta]

ok I couldn't stand it. Although I have used a torque with an extension on several occasions, I have never had a problem. When I use an extension I try to support the head of the torque wrench with the palm of my hand to prevent a side load on the nut. It always works good. You can see that in the pics. The first picture is of a 3/4 inch socket on the torque wrench, torquing the nut to 50 foot pounds. The second pic is a line drawn on the two nuts after they were torqued. The third pic is of the nut backed off. The fourth pic is 3/4 inch socket on a 24 inch extension torquing the nut back to 50 foot pounds. And the fifth pic is of the two marks again lining up. So in conclusion, the extension has nothing to do with it. As long as everything is properly supported, your hand is in the proper place on the extension handle and your torque wrenches should be checked for accuracy. The torque wrench I use is a snap-on click type. When you get to the preset foot pounds the wrench will click.
That's it kids. Have fun.

Willie Buchta

[sheribuchta]

A couple of more pics.
Willie Buchta

[jl222]

ok I couldn't stand it. Although I have used a torque with an extension on several occasions, I have never had a problem. When I use an extension I try to support the head of the torque wrench with the palm of my hand to prevent a side load on the nut. It always works good. You can see that in the pics. The first picture is of a 3/4 inch socket on the torque wrench, torquing the nut to 50 foot pounds. The second pic is a line drawn on the two nuts after they were torqued. The third pic is of the nut backed off. The fourth pic is 3/4 inch socket on a 24 inch extension torquing the nut back to 50 foot pounds. And the fifth pic is of the two marks again lining up. So in conclusion, the extension has nothing to do with it. As long as everything is properly supported, your hand is in the proper place on the extension handle and your torque wrenches should be checked for accuracy. The torque wrench I use is a snap-on click type. When you get to the preset foot pounds the wrench will click.
That's it kids. Have fun.

Willie Buchta

   

  Thanks Willie JL222

[theazoldcrow]

    Willie!  How do you find the time for all this?  I love it.  Some of us have to be "shown" to learn, I'm one of those.  Seeing is believing for us backyard wrenches!   Thanks again for your taking time to teach!    Crow

[manta22]

I suspect those that thought than an extension on a torque wrench changed its torque were confusing that with using a torque wrench on a crowfoot wrench. That does change the torque because it is offset from the axis of the bolt/nut.

Regards, Neil  Tucson, AZ

[McRat]

I suspect those that thought than an extension on a torque wrench changed its torque were confusing that with using a torque wrench on a crowfoot wrench. That does change the torque because it is offset from the axis of the bolt/nut.

Regards, Neil  Tucson, AZ

Think about force vectors.

When using no extensions, the force is almost inline with the bolt face.
When using extensions, the force is actually trying to push the tool over, not rotationally.
Your second hand resists the "push-over" force, but it is not perfect.  It resists the torsional force.

When I was working in aerospace, they specified whether or not you could use an extension, and when calibrating, the answer was always no.

With highly experienced personal, I imagine it wouldn't matter.  With just normal folk, the way the wrench is held and used can make a significant impact on the torque.

[willieworld]

HHHHHHHMMMMMMMMMMMMMMMM  sorry i didnt realize these guys were building a space shuttle --i thought maybe they were just tightening a couple head bolts--------willie buchta

[McRat]

HHHHHHHMMMMMMMMMMMMMMMM  sorry i didnt realize these guys were building a space shuttle --i thought maybe they were just tightening a couple head bolts--------willie buchta

Yeah, I worked on the Space Shuttle, but they never let me drive the damn thing. 

The first time I heard the "no extensions" rule was from my Auto Shop teacher, Mr. McFarland.  I doubt if he's not around anymore.
Then when working for McDonnell Douglas and Rockwell International, I was told the same thing.

But it might have just been picking hairs outta horsepoop.

[willieworld]

Heres the test using the crows foot and a torque wrench set at 20 foot pounds. I thought I'd make the test different so I used a 3/8 bolt about 5 inches long. I clamped the head of the bolt in the vise with the threads sticking out the side. I put a couple of washers on it torqued the nut down with a socket and marked the nut at 12 o'clock. I put on a 24 inch extension torqued down the nut and the mark was at 12 o'clock. Put on a crows foot turned it to the inside torqued down the nut and the mark was at 12 o'clock. Put the crows foot on pointing towards the outside torqued the nut down mark on the nut was still at 12 o'clock. In between each tightening I'd loosen the nut two turns. So I guess its not rocket science. It's just landspeed racing.
Willie Buchta

[willieworld]

more pics

[manta22]

Willie;

If you used a shorter torque wrench it would make more of a difference. The offset of the crowsfoot adds to the length of the wrench handle in one direction and subtracts in the other-- there is a difference in leverage but it may not be too visible with a long handle wrench.

Regards, Neil  Tucson, AZ

[Glen]

Here's a hint.  Google torque wrench users manual, lots of information.