Re: Hardened Cranks

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Interesting stuff......... 
what are your thoughts on the Coatings
offered by various Shops ?

I recall Kal Gard as one of the earlier
coatings marketed to the mass market
briefly.

The places that do the ceramic piston and
combustion chamber coatings now offer
coatings for crank & rod journals etc.

Another question is of fillet rolling - something
done to the Turbo Buick Grand National Crankshafts
to ward off cracks forming.   As I understand - these
filletts are rolled under high pressure during manufacturer -
is it possible to do this to welded up cranks  and 
cast crankshafts alike ?




On February 19, 2005 Bruce Hevner wrote:

> We re-grind our own cranks and I'll have to tell you I have not noticed any
> difference in "hardness" of AMC cranks compared to other stock cranks. If
> you are referring to "Nitriding" or "TuffTriding" I certainly haven't seen
> ANY AMC cranks like that. Not that there AREN'T any (never say never),,, but
> I haven't seen them.  Could you please give us specific part numbers of
> these "hardened" cranks? What numbers are they when you start and what are
> you "hardening" them to?
>  We tried sending Chebby cranks out to be Nitrided ( thinking it was better)
> back in the 70's. They were straight to start but the process warped them
> several thousandth's making them unusable. Maybe the process is better now,
> I haven't had one done in years. It's not really a "strength" process any
> way. It is a surface hardness process meant to reduce wear.
>  I ran into it again in the late 70's when I started doing a lot of Honda
> work. All their cranks were Nitrided. But the bearings had worn through the
> treatment (it's only a few thousandth's thick at most) and needed to be
> reground. We were told they could NOT be reground and reused unless they
> were also Nitrided. This is MUCH to expensive a process to use on a stock
> rebuild like a Honda so we reground them and used them untreated. It was
> several years before we saw one come back for a rebuild with an untreated
> crank. Although there WAS more wear to the crank than an untreated one, it
> HAD worked. In fact MOST stock cranks are NOT Nitrided and work just fine
> that way.
> Is Nitriding better? YES it does reduce wear on the crank. I don't believe
> it's necessary for the average street engine though. It can't be done
> cheaply enough to justify the cost in my opinion.
> But hey,,,, that's just me!!
> Bruce Hevner
> 
> 
> 
> 
> 
> .


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