my take on torque

[auditude at cox.net]

While half-following the thread on torque and all the answers offered, at one point I forgot what the question was.  But I think the question is how much torque is actually applied to the crank bolt when following the manual using the recommended tools and technique.

I'm not familiar with the math involved in calculating the resultant torque at the bolt using the tool, which probably has a known length.  But is the math formula being disputed?  Is there more than one being offered?

To me it seems intuitive to think that any torque wrench of any length is intended to produce the same torque at the bolt when used as intended.

I do believe the factory tool is a torque multiplier, as well as a way to get to the bolt without pulling too much off the front of the car.

I don't know enough about this stuff to be able to say whether putting a pipe or extension on the handle end of a torque wrench will affect it's accuracy.  I am temped to say that it will, since I believe you are not supposed to touch the wrench anywhere but the handle.  If I put my hand in the middle of the torque wrench opposite the direction of force, for example if I was pulling up on the handle, I imagine the hand in the middle of the wrench would reduce the amount of "handle" force getting to the bolt.

I believe the above is only relevant because were are talking about improperly using the torque wrench.  I think the discussion about torque wrench length is totally pointless.  If you use a 2 foot torque wrench properly or use a 2 mile torque wrench properly, the resulting torque at the bolt is the same.

So in summary, I think the torque applied by any correctly used torque wrench is measured at the socket.  So the question becomes, what is the torque at the bolt when the stupid factory tool is used?

I'm sure I don't understand the rest of it (and maybe the part above!), because there has got to be something more for there to be such a long thread.  I suspect adding length from the socket end of the torque wrench is not the same as adding length to the torque wrench itself.  (by that I mean using a longer torque wrench, which wouldn't change the applied torque, but would require less force on the handle end, and more distance)

It's possible that a simple formula for extending the lever could be used to calculate torque.  But, my hunch is that since the "click" occurs in "the middle" of the combined torque wrench/factory tool, instead of near the bolt, there there is another factor to consider.

The one analogy about the four corners of the torque wrench, pushing in four directions, seems to make a little sense.  I don't know what happens with the "extra" three directions of force, but the only direction that the torque wrench can go is the direction the crank bolt is turning.  So, the torque wrench is pushing the factory tool clockwise with a certain amount of force.  If that force is multiplied by the factory tool due to its length, then it should be calculable.

Hmmm.  So if the "click" point of the torque wrench is not at the same point as the center of the bolt being tightened (it's in between that point and the handle), then at that point it is not measuring the "twist" that's occuring at the bolt, but the force applied in a single direction at the click point.

So, by using the factory tool you are moving the click point further away from the axis of the bolt than it already is.

My conclusion is that the formula for calculating the effect of lever length on torque should be applicable to this problem.  In other words, adding length to either side of the click point should have the same effect, since it is measuring force in a single direction, and not the "twist" dimension (directly).

Make sense?  Or just more talking out of asses? :P

I also believe that getting it as tight as possible with whatever you can manage is probably fine as long as you have some grunt.

Cheers,

Ken