I ran nitrided cranks with NO damper for hundreds of races and countless
hours in dyno time and in the end broke one crank at the usual spot before
the SCCA allowed aluminum flyhweels. None of my endurance engines ever had
a damper and the engines all survived after dyno time, four hour long
practise sessions and then a twelve hour race, then more races in SCCA
form. But if I had a TR-250 or a TR-6 I'd be first in line for that damper.
*Never be beaten by equipment.*
On Fri, Dec 6, 2013 at 9:59 AM, Chuck Gee <chasgee@aol.com> wrote:
> 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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> >
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