Great Book on Nuts Bolts & Fasteners
I highly recommend the book "Carroll Smiths Nuts Bolts Fasteners and Plumbing Handbook". It is written in laymans language and you dont need a phd in math or mechanical engineering to appreciate it. It is also pretty entertaining. And short.
All bolts stretch to a cetain extent, that is what keeps them tight. But at a certain point, the metal wont snap back from its stretched position. High strentgh bolts are harder and more prone to breaking as they are less elastic. Over tightened fasteners are a big no no with any fastener.
Its available from Amazon Books, 15 bucks or so.
'84 190E 2.3
'83 Porsche 944 (track car)
'84 Porsche 944 (parts car)
85.5 Porsche 944 (sled)