grade 8 (was Re: Engine stand)

[Richard Welty <rwelty@domain.elided>]

On Mon, 26 Aug 2002 18:39:37 -0700 Tony Sims <simstony@domain.elided> wrote:
>  IIRC, I ended up with 2 of
> the
> arms sharing one slot on the pivot plate.  Also, get some grade 8
> hardware
> with plenty of big fender washers to support the upper block holes so you
> don't mangle 'em.

ok, i'm going to ask a loaded question here?

why grade 8? what do you mean by grade 8, the SAE designation (used only on
traditional non-metric fasteners) or do you really intend to state 8.8? (a
metric designation, corresponding roughly to SAE grade 5).

i can see no compelling reason why this application requires an SAE grade 8
equivalent bolt. many people insist on using SAE grade 8 "because it's
better" when usually it's nothing of the kind.

SAE grade 5 is softer, more ductile, which means it will bend some time
before it breaks. SAE grade 8 is less ductile, less inclined to bend, but
will tend to break more suddenly when it lets go.

people are very insistent about things like grade 8 when they're bolting,
say, roll cages to the floors of production cars. i've never quite figured
out why. the floor will give way long before a grade 5 bolt will.

likewise, a properly installed grade 5 bolt should support an engine on an
engine stand just fine, if there are enough of them and they're torqued
properly.

richard
--
Richard Welty                                         rwelty@domain.elided
Averill Park Networking                                         518-573-7592
              Unix, Linux, IP Network Engineering, Security
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