TORQUE WRENCH QUESTION

It will definitely give you an error, but until you asked this, I had no idea that I haven't a clue why it works that way.

The error discussed has to do with using a tool not in line with the torque wrench, like a crow foot. As you can see, the torque needs to be recalculated because the tool cannot correctly "sense" the torque actually applied.

Any error you are going to get with a 12" extension is only going to be the error of being "off center" from the bolt you are torquing. So work hard to stay "square" to the bolt and you are fine.

Hi Ed! I appreciate your reply. It's quite simple now that you explained it.

By the way, I was the one who posted the question but I was not logged in at the time.

Have a nice day.

Uh, oh. I misread your post. You're asking about a 12" extension on the 1/2" drive axis, aren't you. Like this,

That won't do anything at all as long as you hold it straight. The other extension can be calculated from this

Thanks for that info. I never considered using an open-end on a torque wrench - never had the need but, it is a possibility. I will archive the URL you included with your post and keep it in mind. Thanks.

I wouldn't get in a real hurry to add them to the tool box, but once you do you'll wonder...

From a theoretical standpoint, using an extension such as illustrated is not the best idea. If you insert an extension between your socket and the torque wrench, such as the 12 inch long extension being discussed, then (theoretically) there is some torque being distributed through the extension. As a test, I've seen cheap extensions twist during torquing of bolts. It relates to the fact that there is no perfectly rigid body; all members are subject to deflection, whether twist, linear, tension/compression, combination, etc.

However, from a practical standpoint, extensions are acceptable and sometimes necessary. I torqued many a cylinder head bolt in the vehicle as a kid which required extensions to clear components. Avoiding extensions when possible is the best policy, but sometimes necessary. The main thing is to ensure the extension is in the same axis as the bolt/stud to avoid rounding the bolt/nut during torquing.

After reading all the posts, I went and got a 2" extension which should minimize twisting of the extension and misalignment. Thanks to all.

I assume you mean that if a 12" extension is installed between the torque wrench and the socket the torque applied to the bolt will be different than the torque reading on the wrench. This may be so because of the torque used to distort the extension but I don't know how to calculate the difference. I hope a mechanical engineer will comment on this!

Is the 12" extension necessary? If so I suggest you ask the manufacturer for advice because other mechanics have probably faced the same problem.

Dennis Waller

I realize that we're talking about relatively miniscule loads here but, it's very important to remember that "torque" only indicates how much resistance is encountered when a nut or bolt head is being turned. Torque is not a measurement of bolt tension! And of course, it's the correct bolt tension which keeps your bits and pieces from falling apart.

Regardless of whether or not even a calibrated torque wrench is used, one may or may not acheive the necessary clamp load that the designer had intended. In fact, not only is under-tightening possible, so is over-tightening - at the same "torque" setting!

Here's a link which helps to explain this very important caveat.