On Tue, 25 Sep 2001, Scott Hall wrote:
:
:On Tue, 25 Sep 2001 LBC286@aol.com wrote:
:
:> On another list there is a heated discussion about using all grade 8 bolts on
:> restoring a car. Can anyone give me a simple explanation as to why it may or
:> may not be a good idea to replace grade 5 with grade 8?
:
:umm...cost? that's the best I can come up with. lots of stuff wouldn't
:need a grade 8, but if you don't mind payin' for 'em...
Well, cost is one factor (and a big one!). One good reason not to use grade
8 where grade 5 or 2 is spec'd is tightening torgue. A bolt is tightest
when it stressed nearly to its elastic limit -- the point at which the
threads stretch permenatly. For grade 8, that's very much higher than it is
for lower strength grades. If all you're doing is clamping something
together, that's not much of an issue. If your threading the bolt into a
threaded hole in a cast piece, you risk ripping the threads out of the hole,
or bolts that are more likely to come loose. A loose bolt is more likely to
brake than a properly fastened one.
Most automotive applications, grade 5 is suitable.
--
dscheidt@tumbolia.com
Bipedalism is only a fad.
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