Helicoil Shrinkage at Installation

You have a good eye OMM! I shoulda explained... the one on the right is the exact same part as the one on the left (both out of the same bag of 10), and started out looking exactly like the one on the left. The one on the left has not been installed.

The one on the right is the one that got installed and I subsequently turned all the way through the flywheel and out the back. The wire is deformed and pushed into a smaller diameter as it gets turned into the hole. The smaller diameter forces the helicoil wire to 'wrap' itself into more turns.

I never realized that the reduction in diameter would lengthen the helicoil so much. Or permanently deform the wire so much. Just thought it was interesting and worth sharing.

FWIW... this is for an 8mmx1.25 thread.... pretty much the same as a 5/16" coarse thread.