Metwrench@aol.com wrote:
>
> Hi Gang,
>
> Have any of you had a crank ground down ? Has the machine shop told you that
> after is was ground that it would have to be hardened ?
Horse hockey! I don't know about the later Triumph products, but the earlier
ones
aren't hardened at all from what I can tell. If they are, they certainly
aren't in
the Rockwell C 53-58 range, which is typical for hard surfaces such as
journals. I
put a small dent in a journal of the one I was working on _before_ grinding,
without
any effort at all. As for the assertion that the cranks are case-hardened, I
very
much doubt it. Case-hardening is an old process very much unsuited for modern
production methods.
Further, if your machine shop told you the crank needed to be "nitrated," they
probably meant they were going to spread the fertilizer on _you_. The process
is
known as "nitriding." It's very simple. Put the crank in a chamber, evacuate
it,
pump in ammonia gas, and raise the temperature to about 800 deg. F. Let it sit
for a
while. That's nitriding. It produces a very thin skin of hard iron nitride on
the
surface of the journal. It would improve the life of the journal, but I'm
doubtful
that it's a necessary process. How much did these people tell you it would
cost?
--
My other Triumph doesn't run, either....
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