Actually, even reuseable (i.e. non-"torque to yield") studs do stretch
bit, and an accurate measurement of this stretch gives a direct measure
of the compression placed on the mating surfaces (which is what you are
We used to do this when I worked for Erickson Tool (when you make the
tools that other precision machinists use, you have to be very picky
>Aaaahh yes..... bolt stretch... BUT not all head
>studs are the 'torque to stretch' type. Rod bolts yes...
>but MG studs can be re-used. Triumph studs are a
>torque to yield type and must be replaced each time.
>....or do I have that bass-acwards. :-)