On Sep 12, 1:54 pm, "hls" > wrote:
> "C. E. White" > wrote in message This is done
> using specialized machines
>
> > that sense a change in the stress strain relationship as the bolt reaches
> > the yield point. This is a very good way to torque bolts for variable
> > loads, but difficult to duplicate in a repair environment.
>
> I have seen bolt elongation gauges advertised and recommended for
> performance
> engine building. They are not so expensive.
>
> I have never used one of them, and wonder if anyone here has any comments on
> them.

If you know the elastic modulus of the bolt that you are tightening,
it is theoretically MUCH more accurate than torque and completely
takes thread and nut/surface interface friction out of the picture.
However, I have not used one either.

nate