In a message dated 6/5/05 11:47:21 PM Eastern Daylight Time,
davriker@pacbell.net writes:
> If I'm not mistaken, grade 8 bolts are less prone to stretch, ie more
> brittle. In an accident, I think you'd want the bolts to stretch, not snap.
>
> I'd go with the regular grade bolts.
What did I learn at the Bowman tech session at the Austin Healey Conclave in
Indianapolis? Well, I keep seeing that thing about Grade 8 bolts being
brittle, painting the picture of a bolt being dropped and shattering into
pieces,
like a piece of glass and Grade 5 bolts stretching like a rubber band.
Actually
there is a bit of myth about that. All bolts stretch to some degree. When
you torque them up to specs, you are actually stretching them. And they do not
return to their original shape (How long since you have replaced YOUR wheel
studs?). The thing is that a Grade 5 bolt might stretch a bit more than a
grade 8 under stress, but it will actually snap before the grade 8 starts
thinking about stretching due to the stress, much less breaking. I don't have
time
right now to look the values up, but for my money, I will use Grade 8 bolts in
my roll bars.
There is, by the way, a best of both worlds. There is an alloy called
Bowmalloy, made by a bolt company named Bowman--I think in Cleveland. I was
impressed by it's specs when I saw them.
They also confirmed that a "lock" washer is useless, except acting as a
washer. They said "You keep using them, we will keep making them!" with a
smile.
This might start another "thread", ya think? 8^)
--David C.
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