A lighter flywheel doesn't induce vibration, and given that the flywheel is
rigidly bolted
to the crankshaft, I'm not sure that vibration absorption is part of the
flywheel's
function. The large rotating mass helps to smooth out the rather uneven firing
impulses of
an inline-4 (maybe that's what folks mean by "absorbing vibration") by
providing the
inertial momentum to keep the crankshaft assembly rotating smoothly between
power strokes.
The advantage of a lighter flywheel is in the reduction in rotating mass. The
lower
inertia allows revs to build faster, and of course, to spin down quicker too.
Back in the
day, when I was racing motorcycles, my brother and I both performed this type
of mod to
our 125cc Yamahas, replacing the heavy magneto/flywheel with a unit which not
only
weighed less than half as much, but was smaller in diameter, rotating inside
the stator
coils. The reduced inertia changed the engine note from "vroom, vroom" to
"wing, wing"
;^)
Racers always like to lighten their vehicles, and in lightening the flywheel
you get a
double benefit by reducing a mass that is not only translated, but rotated -
getting a
quicker-revving motor and an overall lighter vehicle out of the deal.
Gary McCormick
San Jose, CA
P.S. - Sid, what was the "disturbing info" which your friend shared w/you?
sidney raper wrote:
> Pardon my ignorance, but why the big fuss about a lightened flywheel?
> Doesn't that induce vibration due to the lack of the dampening effect that
> the heavier one would have? Wouldn't that lead to more fatigue failures on
> a lot of stuff and make driving more nerve wracking?
>
> Not trying to throw cold water on the idea as it is great for racing, but on
> the street (exclusively), it seems to be a waste of money imho.
>
> Am I way off base?
>
> On a different subject, what brand/grade of oil are folks using in their
> Roadsters? A former mechanic gave me some disturbing info about some oils.
>
> Thanks,
>
> Sidney Raper
> 1964 1500
> 1967 SRL311 00060
> 1967 SRL311 00076
> Jacksonville Florida
> http://www.geocities.com/roadsternut/index.html
>
> >From: Sexmnypwr@aol.com
> >Reply-To: Sexmnypwr@aol.com
> >To: <vlaury@earthlink.net>
> >CC: <datsun-roadsters@autox.team.net>
> >Subject: Re: Lightened flywheel
> >Date: Thu, 16 Aug 2001 17:53:21 EDT
> >
> >Hey Vic and all,
> >
> > Back when I built my 3.2L for my 240Z, I had Top End Performance lighten
> >my
> >flywheel down to 15lbs from 25lbs. Take a look at this link:
> >http://www.racetep.com/flywheel.html
> >They have a great machine shop and I'm sure they'd do a Roadster flywheel
> >for
> >the same $150 as the Z flywheel. Not sure how much the Tilton or other
> >aluminum flywheels are, but this is a good alternative.
> >
> > Stan Wada
>
> _________________________________________________________________
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