Re: Crankshaft hardening specification

["Glenn A. Merrell" <gmerrel@domain.elided>]

Hello Dave,
    I'd like to hear more about nitride process not being suitable for Stag
cranks.  If it is not suitable for Stags, would it not be suitable for other
Triumph models?  My engine builder did a grind and microscope check to test
grain on the crank metal and suggested nitriding.  If for some reason it is not
suitable, I need to have some details on what the difference is for "tufriding",
which I thought was a nitride process.
    To Tim, Nitriding actually "swells" the metal according to my engine
builder, so the grind should accomodate the type of hardening process to get the
correct final OD on the crank.  But I'd like to hear more about "Tufriding"

Regards,
Glenn Merrell

Dave Biggs wrote:

> Tim Buja wrote:
> >
> > I'm having my crankshaft ground down to .010" undersize, and I've received
> > a number of suggestions that I should have the crank re-hardened to ensure
> > that it will last more than a few hundred miles.  Does anyone have the
> > hardening spec handy so that my engine rebuilder can get it right the
> > first time?
> >
> > BTW, I'm using stock (Vandervell) crank and rod bearings, .010" undersize,
> > if that makes a difference in the spec.
>
> I don't know the full technical spec but I just asked for my crank to be
> tuftrided which I gather is the best process for a Stag crank. Evidently
> the casting material is not suitable for nitriding.
>
> It cost me about 30 UKP but I had to do the final lapping of the
> journals with oil soaked wet & dry just to polish them up a bit. However
> they still looked a dark grey colour afterwards. I figured if you polish
> them to shiny metal them you've just polished the hardened surface off !
>
> Hope this helps,
>
> Dave.
> --
>         Dave Biggs
>         Senior Design Engineer
>         Fujitsu Telecommunications Europe Ltd,
>         Birmingham Business Park,Solihull Parkway, Birmingham, B37 7YU.
>         mailto:D.Biggs@domain.elided  tel: 0121 717 6094  efax: 0121 717 6014