[Healeys] Fly Wheels

[Alan Seigrist]

Dave / All -

Well for the original 100 motor, with the 45# flywheel (try lifting one of
these), lightening will definitely make a difference, and in fact will help
with braking of the car because the centripital force will cause the car to
go sideways when you step on the brake.

Many of you out there with an original BN1 BN2 will likely notice that
sometimes you have to adjust the steering wheel under hard braking - this is
not because the shoes are out of alignment, this is because of the rotating
mass of the flywheel.  You will notice it the most doing hard braking at
freeway speeds when the motor is at high RPMS.  Not the safest thing in the
world, and when my BN1 is up for a rebuild the first thing to go will be the
45# flywheel!

These weird braking affects are especially true for very early BN1s like
mine, which are the lightest of the healeys ever made.

Best Regards,

Alan


'52 A90
'53 BN1
'64 BJ8


On 8/31/07, Dave Russell <rusd at sitestar.net> wrote:
>
> Hi Bill,
>
> I don't know if this helps or not.
>
> It's all about inertia. More mass requires more power/time to change
> speeds.
>
> in a car with a 3.5 to 1 first gear & a 4 to 1 axle, in first gear,
> there is a 14 to 1 mechanical advantage for the engine to accelerate the
> car mass.  Thus the engine/flywheel only has to overcome 1/14th of the
> total car mass. In top gear the engine/ flywheel has to overcome 1/4 of
> the total mass.
>
> Bottom line, for a given car weight, a light flywheel improves
> acceleration in proportion to the gear tht the car is in. Much more
> improvement  in first gear than in top gear. And of course much faster
> throttle response when the clutch is not engaged.
>
> My personal experience with a BN2 is that a 13 lb flywheel vs the
> original 40 lb makes the engine/car more responsive in the lower gears &
> between gears. On this very long stroke engine, it has no noticeable
> effect on idle quality, engine starting, or ease of getting the car
> rolling from a stop.
>
> Regards,
> Dave Russell
> BN2
>
> Bill wrote:
>
> >  Hi Greg,
> >
> >  While I'm sure there are many others out there much more versed in
> >  physics than I am, the "#" sign means pounds, as in weight. It takes
> >  more horsepower and time to spin up 42 pounds than it does 23
> >  pounds. That means quicker acceleration and deceleration. I can
> >  easily tell you the results, just not necessarily why. Would
> >  somebody please help me out here?
> >
> >  Many thanks,
> >
> >  Bill Barnett '53 BN1 # 663
> >
> >  Go2ghill at aol.com wrote:
> >
> > > What at the numbers for the fly wheels mean, and why is one better
> > > than another. Greg BN4
> _______________________________________________
> healey.nut at gmail.com
>
> Healeys at autox.team.net
> http://autox.team.net/mailman/listinfo/healeys