Re: [MV] The nuts and bolts of the matter... (More questions)

From: Brandon Kunicki (c322348@yahoo.com)
Date: Wed Jan 03 2001 - 08:21:59 PST


Another problem you may run into is that Dodge (and
others) used fasteners made to their own
specifications. Hence the "F" marked bolts on Ford
Jeeps, etc.

I don't know what material was used to make these
bolts, you would have to find the company proprietary
specifications to be sure.

A connecting rod bolt would almost never have a
commercial "grade" equivalent because it is typically
not made to standard commercial specifications.
Diameter, head shape, thread length, dimensional
tolerances, material, etc. might all be unique to that
fastener for that specific application. Due to
economies of scale and factory assembly methods, many
trucks use non-standard fasteners (extra thread length
to account for tolerance build-up, pointed ends for
easier installation, special diameters to accomodate
rubber bushings, etc.).

If you only use NOS fasteners from reputable dealers
you would be OK. That isn't always practical or
possible for financial or supply reasons. I used Home
Depot fasteners to attach the troop seats onto my
HMMWV because the result of a failure would not likely
be serious. I would get the factory bolt to replace a
suspension component though, not a piece of threaded
rod with a nut on either end!

If you have the original bolt, compare it with any
substitute. Most structural bolts (body and frame) on
light trucks (under Deuce-and-a-half sized) I would
expect to be grade 5. Engine and drivetrain fasteners
could be anything that meets the specific needs of the
application. I would beware in internal areas of the
engine, transmission, and differential as some of
these are highly stressed.

I'm not sure there is a simple answer to your
question. Each case must be looked at individually.
You must play engineer everytime you make a material
substitution and try to second guess what the
manufacturer's engineering staff (with years of
training and experience) were thinking.

I would start by assessing the risk of failure. If one
engine to bellhousing bolt broke, you could probably
get by with the other 7 of them. If the Home Depot nut
holding the steering arm in place broke off, the risk
would be much greater. Also consider that strength may
be a secondary issue. You can install a stronger nut
to hold that steering arm, but if a cotter pin won't
fit to keep it from vibrating off.....

BK
-------------------------------------
> Would somebody care to give some further advice as
> far as what grade fasteners
> should go where on an M-37 (Engine, body,
> suspension, etc.)? I plan on not only
> using this advice for my truck, but also to pass it
> along to other M-37 owners.

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