Bolt torque discussion

pittsburghracer said

Before I call it a night for the go by the book guys proper torque to yield puts x amount of stretch on each bolt. Sooner or later the elasticity of that bolt is lost. How do you know when this occurred unless you Mic each bolt and mark each one for size. Some of my studs are over 30 years old so just something to think about

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We allowed for 5 torque cycles/clamp loads on a bolt before throwing it away...

Example: for a connecting rod... One clamp cycle is used in machining to clamp the cap to the rod and machine the crank bore... Then the rod and cap are split so you can install the piston in the engine... That is two torque/clamp load cycles on the bolt to get the engine out of the factory...

We allowed two clamp loads for the field - one for service, and one for rebuild... However, they did not take in account for another cycle if you plastic gauge/check your clearances...

So the engine factory gets one repair for themselves... A rod and piston can only be reused/recycled once in the factory before it is scrapped....

A typical connecting rod bolt will stretch an average of .001' - .0015" per clamp load... I have seen it get up to .0025" sometimes...