Re: Seat Belts

[Richard Welty <rwelty@domain.elided>]

At 11:14 AM 12/29/98 -0700, Tom Mandera wrote:
>Also, I assume I want Grade 8 everywhere...

...

>They're only Grade 5.. I installed the ratchet
>mechanism while at RMIHR and didn't have my Grade 8 replacements handy..
>with THESE bolts, the primary force will be *across* the bolt, vs
>in-line.

grade 8 is a little bit over used, in my opinion.

you're better of with known good (i.e., know to not be counterfit) grade 5
bolts than with uncertain grade 8 bolts.

the tradeoff when you go from legitimate grade 5 to legitmate grade 8 is
that grade 8 resists plastic deformation longer, but breaks more suddenly.
i'd rather have the bolts for my harness deform instead of shatter.

other issues more important include things like avoiding sheer mountings
when possible, and making sure that the bolts used have appropriate
shoulders, so that you aren't loading the bolts on the threaded area. these
issues are all too often overlooked.

see Carroll Smith's book on plumbing and fasteners for more gory detail
than you  can imagine on the subject. it's available from Classic
Motorbooks. i don't recall the complete title off the top of my head, but
it's a really great book -- the subject is plumbing and fasteners for motor
racing, but it's so good that many mech e's and materials guys have it on
their shelves.

it's the 4th book in a series. the 3rd book, _Engineer to Win_, contains
more about basic metalurgy that you are likely to ever want to know, unless
you're a metalurgist.

richard