Flywheel bolts

[Bonzo]

When I say stretch a fraction, I am only talking microns.

With the bolt under tension when cold the bolt would retain any elasticity it has.
Once the bolt has been subjected to many hours, within a relatively high tempature enviroment, the material of the bolt will become " Normalised " thus the original few microns of stretch will be lost.

The bolt will allways maintain a good mechanical grip as all things are taken into account when the optimum torque setting is calculated.

Re-using the same bolt, in theory, would be like using a bolt that is a bit of an unknown quality. Different engines will have been subjected to different levels of heat during their lifetime.

This may explain why such bolts should be changed as a matter of routine.

Cylinder head bolts also work in a very similar enviroment & very few are re-useable for similar reasons.