Grade 8 vs Grade 5

Glenn · Apr 28, 2006

Old Bill said:

If they were used, it wouldn't surprise me. Bolts "hold" things by virtue of stretching. There's a tiny amount of elasticity in a bolt, and by tightening to a given torque, you are avoiding over stretching the bolt. (The whole point of torquing to a given point is to place the bolt stretch at such a point that the cycles are nearly endless, but still hold the item tightly.) Tighten in exess than the "correct" torque, and you shorten the bolt's life. Taking into account that there are only so many cycles of stretching a bolt can go through before it fails at X torque, and that a head bolt will stretch with the engine heating up and cooling off, and then re-using it and torquing with anti-sieze (thus causing more torque than specified), I could see how you can take the bolt beyond it's failure point.

I STRONLY recommend the Carroll Smith book "Nuts Bolts and Fasteners", see it HERE.
It WILL break a lot of misconceptions on how bolts work, and you will rethink a lot of how you use them.
Click to expand...

That's why I said "good" bolts.

Old Bill · Apr 28, 2006

Glenn said:

That's why I said "good" bolts.
Click to expand...

R) Even so, "good" bolts can be subject to the same. If you REALLY want to get a good bolt, you'll have to hit an aviation supply. Even grade 8 can be a "bad" bolt. (Ever wonder who keeps track if bolts are in spec or not? Nobody. ) Trust me on this, get the book. WELL worth it.

blevisay · Apr 30, 2006

Actually guys antisieze does not count.period .

all specs are given with oil unless noted as "dry" and all bolts have a torque spec.

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Grade 8 vs Grade 5

Glenn Kinda grumpy old man Staff Member

Old Bill Aggressively passive....

blevisay Oh Noooooooooooooooo! Staff Member

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Grade 8 vs Grade 5

Glenn Kinda grumpy old man Staff Member

Old Bill Aggressively passive....

blevisay Oh Noooooooooooooooo! Staff Member

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