I may be incorrect here, but isn't nitriding a surface harding? It helps with
wear on the Bearing surfaces. The best precaution I have found regardless if
its a stock crank or billet, is making sure the radius at the bearing
Journals are as big a radi as you can. Even if you have to chamfer the
bearings. Shot penning a stock crank will also help smooth the edges. Not
Always, but a crack will start at a Corner or sharp edge.
Tony G.
> From: chasgee@aol.com
> Date: Fri, 6 Dec 2013 11:59:23 -0600
> To: tr4racing@googlemail.com
> CC: fot@autox.team.net
> Subject: Re: [Fot] aftermarket crank dampeners and pullies for TR4's
>
> And nitride it to try and keep the crack from starting in the first place.
>
> Chuck
>
> > On Dec 6, 2013, at 11:39 AM, "MadMarx" <tr4racing@googlemail.com> wrote:
> >
> > Unusual spot to break because the torque rises from front to rear. So the
> > first spot to break is the rear end with the highest load.
> >
> > I'm a civil engineer, so I have a small clue about forces.
> > If the crank has no flywheel and not pulleys, just the crank with rods
and
> > pistons it can freely bend on high load like a two field beam.
> > A flywheel stops bending because the flywheel don't like to wobble, it
> likes
> > to run straight so the cranks rear end is forced to run straight, while
the
> > parts between the mains swing. That induce forces into the last counter
> > weight and maybe lead to a crack.
> > The same with a damper on front. It reduces the swing in the middle
between
> > main 1 and 2 but it rises the force on the counter weight.
> >
> > As a civil engineer I would say, let it swing and make the flywheel and
> > clutch as light as possible and you get the most out of the crank.
> >
> > Cheers
> > Chris
> >
> > -----Urspr|ngliche Nachricht-----
> > Von: fot-bounces@autox.team.net [mailto:fot-bounces@autox.team.net] Im
> > Auftrag von John Hasty
> > Gesendet: Freitag, 6. Dezember 2013 15:54
> > An: 'Michael Porter'; 'Randall'
> > Cc: fot@autox.team.net
> > Betreff: Re: [Fot] aftermarket crank dampeners and pullies for TR4's
> >
> > For what it is worth, we got 10 race weekends on our last rebuild running
a
> > damper from BFE. The crank broke between # 1 rod and front main on last
> > race, last lap, last turn while running 1st. in EP. I regularly turned
> 6500
> > in 2nd, 3rd, 4th and 6200 in OD. The motor always ran smooth with no
> > vibration I could feel even with the front engine plate bolted directly
to
> > the frame
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> >
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