VF article-Torque Wrench Extension

[jab35]

Another excellent edition of Vintage Ford arrived yesterday. On pages 40-41 the author describes how to make a three-inch-long extension for torquing head bolts near the firewall. He concludes the article by saying "No, the added 3" does not change the amount of torque applied." No explanation is given, but it seems to me this extension could effectively add up to 3" to the length of the handle, making the applied torque greater than the indicated torque setting on the tool. Any comments, clarifications? What am I missing in my analysis? Thanks, jb

[Mark Nunn]

You are correct, James. The % increase depends on the torque wrenches handle length and design.

[CudaMan]

I agree, adding an extension will increase the amount of torque applied to the bolt for a given push force on the wrench handle. See the link below.

https://www.norbar.com/Support/Calculat ... 20%2F%20L2

[walber]

I don't have my issue yet so I may be trying to solve the wrong problem.

If it is simply a regular extension that lets the wrench sit high but doesn't effect length there is no effect on the torque force.

I'm thinking if the extension is at a 90 degree offset type, the effect on the torque value would be based on the hypotnuse of the triangle formed by the wrench and extension. For grins, I plugged in 3" as the extension and 22" for the wrench lenght into a Hypotnuse calculator. The hypotnuse or effective lenght of the wrench is then 22.2". OK, not quite negligable but is it great enought to matter when torqueing something on a Model T?

[walber]

Typing at the same time as Mark. The angle of the extension to the wrench is obviuosly critical.

[jab35]

Thanks, everyone, you validated my understanding about how this works.

Apparently, nobody at VF fact checks technical articles? And maybe those who spot an error like this one don't speak up because they already know what they're doing. I know I'd be ticked if I followed that bogus information and doing so resulted in an over torqued and striped a head bolt! jb

[Norman Kling]

I know of 2 kinds of torque wrench. One clicks when it is where it is set. The other has an indicator and you must be more careful to look at and stop at the right place. I had a problem for many years with a leak at the steam vent in the right corner of the head behind the exhaust manifold. I blew many gaskets at that location and many times overheated because the coolant was low. This happened especialy when I checked the coolant before I left home and then loaded it on the trailer and in the morning I left for a tour out of town so spent the night at a hotel. I didn't check the coolant the next morning when we left on the tour. After an hour or so I overheated. Finally I found out what was the problem Many years before, I had broken the threads in one of the bolt holes and When I put a helicoil in the location, I didn't want to drill too far and go into the water jacket. So that bolt was so long it hit the bottom without torquing the head. Since all the other bolts fit fine, I didn't want to grind them all off. So I put a washer under the head of that one bolt. I have not had a problem since. Anyway the point I am trying to make is that the torque wrench reading does not always indicate the torque holding the head down but can be the torque of the bolt bottoming out.
Norm

[Ed Fuller]

I agree with the others.

It will have an effect on the final torque value. However, if you place the extension 90 degrees to the head of the torque wrench it will not influence the final toque value.

This picture explains in better detail.

[ewdysar]

As explained above, if the extension is at 90 deg to the torque wrench, the wrench should be within normal accuracy. This is a expected thing when using crows foot wrench or adapter.

As copied from the interwebs "A crowfoot (or crows foot) torque wrench is a specialized attachment for a standard torque wrench or ratchet that allows you to apply torque to fasteners in tight, inaccessible areas where a regular socket won't fit. It features a head similar to a box wrench that fits over a nut or bolt and a square drive that connects to your torque wrench or ratchet. For accurate results, the crowfoot must be kept at a 90-degree angle to the torque wrench to maintain the correct lever arm length and avoid over-tightening."

So used correctly, the extension described will work as expected and measure the bolt torque accurately. This is common knowledge for those that have used them before (the old guy that showed me how to use one many years ago did explain this), the article probably should have included that information.

Keep crankin',
Eric

edit - here's a link to a page from a company that makes crows foot adapters that includes more details and specific compensation calculations.
https://www.tekton.com/blog/how-to-accu ... oot-wrench

[baltrusch]

Both the Norbar formula and Mr. Redding are correct - how can that be? Look at the Norbar drawing and you will will see that it applies when extending the lever arm. Mr. Redding's tool does not do that, and he is correct in that his method will produce correct torque readings.

[TRDxB2]

Another excellent edition of Vintage Ford arrived yesterday. On pages 40-41 the author describes how to make a three-inch-long extension for torquing head bolts near the firewall. He concludes the article by saying "No, the added 3" does not change the amount of torque applied." No explanation is given, but it seems to me this extension could effectively add up to 3" to the length of the handle, making the applied torque greater than the indicated torque setting on the tool. Any comments, clarifications? What am I missing in my analysis? Thanks, jb

I rethought it.

[RajoRacer]

You might rethink that Frank - it's a lever extension.

[AndyClary]

Since half the time forum members can’t agree on torque specs it’s probably not a big deal.

Andy

[RajoRacer]

Agreed, Andy - kinda like torquing hot vs. cold !