Ron ,
I understand that the tach drive is 4:1 , but the face of the mechanical
tach has a stencil saying 3:1. I suspect that the 4:1 ratio is to compensate
for different diameter generator and crank pulleys . However your note is
still bad news . If I understand you correctly , I would need a tach drive
pulley 3 times the diameter of the crank pulley. Clearly some form of gear
box is needed. On an aside : I've read about people driving mechanical tachs
from the distributor or the cam. Unfortunately that is 2:1
Mark
> -----Original Message-----
> From: Ron Soave [SMTP:soavero@yahoo.com]
> Sent: Wednesday, October 20, 1999 1:12 PM
> To: Hanna, Mark
> Cc: 'spridgets@autox.team.net'
> Subject: RE: Tach drive
>
> That would be a nice solution. The reduction ratio in
> the gearbox is 4:1, the generator output shaft turns 4
> times for every one turn of the tach cable.
>
> --- "Hanna, Mark" <mhanna@ball.com> wrote:
> > Hi Ron ,
> > My car will have an alternator. I would like to use
> > the stock Bugeye tach. I
> > was thinking of driving the tach directly from a
> > jack shaft attached to an
> > appropriately sized pulley. Say 1/3rd the diameter
> > of the main crank
> > pulley. This way I would not need a gear box. Or do
> > I have this backwards ,
> > i.e. the tach has to turn 3 times as fast as the
> > crank ? I haven't spent any
> > time on the problem yet. I will be very interested
> > in what you come up with
> > .
> > Mark Hanna
> > AN5
> >
> > > -----Original Message-----
> > > From: Ron Soave [SMTP:soavero@yahoo.com]
> > > Sent: Wednesday, October 20, 1999 9:58 AM
> > > To: spridgets@autox.team.net
> > > Subject: Tach drive
> > >
> > > List,
> > > I have been working with a machinist in town to
> > try to
> > > come up with gears to replace those in a generator
> > > tach reduction gearbox (it a 4:1 ratio). What we
> > are
> > > trying to do is find spur gears from, say, Berg or
> > > Boston Gear, that can be modified to work. Has
> > anyone
> > > done this research before?
> > >
> > > This was spurred by a failure of my gearbox. The
> > box
> > > is an aftermarket item from "a major LBC part
> > > distrbutor" (begins with M, rhymes with "Toss")
> > with
> > > potmetal gears. Several teeth just kind of
> > sheared
> > > off, and the machinist said the quality of the
> > metal
> > > on the gears was "expletive deleted." The
> > machinist
> > > basically felt the entire box could be hand-made
> > with
> > > high quality for what the aftermarket places
> > charge.
> > > If this ends up being the case, you'll be the
> > first to
> > > know.
> > >
> > >
> > > =====
> > > Ron Soave
> > > "You Are What You Remember"
> > > 1960 Bugeye
> > > 1972 BGT
> >
>
>
> =====
> Ron Soave
> "You Are What You Remember"
> 1960 Bugeye
> 1972 BGT
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