Is this concerning the broken fastener in the front suspension? I lost
track of the thread and have deleted the earlier messages... Anyway, I
have seen the kind of failure that was described (corroded surface
halfway across the diameter of the failure with fresh fracture face on
the remainder) in personal experience.
I heard a "pop!" while doing a U-turn to park in front of my place while
driving my old PL521 ('70 Datsun pickup). Looked in the street and found
what turned out to be one of the three fasteners which secured the
steering box to the frame. I took it to work and had one of our
specialists in the Materials Engineering department look at it. The
verdict was stress-corrosion cracking - a failure that results from
corrosion starting in a stress riser; for example, the sharp root of a
thread. A surface crack starts and propagates through the section (how
quickly depends upon how highly loaded the part is) until the remaining
section is insufficient to take the sustained load or some momentary,
higher load.
This is another good reason to use a corrosion-inhibiting anti-sieze
material when assembling threaded fasteners.
Gary McCormick
'70 2000
San Jose, CA
***********************************************
Philip Erickson wrote:
>
> Teddy
> I more correctly should have said ->
> If you want bolts that are better as good as stock, get a shanked bolt
> the correct length for your application in a grade designed for the
> loading the fastener will see.
> I still question if the bolt failed in shear.
> I have seen grade 5 bolts streach and come loose.
> Phil
> --
> Philip Erickson Phone: (619) 622-7963
> Associate Scientist
> Medicinal Chemistry FAX: (619) 678-8277
> Agouron Pharmaceuticals, Inc.
> 4215 Sorrento Valley Boulevard San Diego, CA 92121
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