In order to run your speedo at 1000 revs you will have to change both
gears in the transmission the drive gear and the pinion; or, of course
you are correct, you can get a speedo shop to build a speedo
"differential" to change the ratio. Should you decide to change the
gear in the transmission I highly recommend you use the new steel gear
that is available. That way if one of the gears self destructs it
will be the pinion gear, which is easily replaced.
The easiest way, and probably the cheapest way, to solve the problem
is to get a different speedo. Old speedos are available at junk
yards, your MG buddies garages, and swap meets. They generally go for
$5.00 to $25.00. I bet someone on this list has a 1000 speedo, just
make sure it is the right diameter.
Larry Hoy
Denver, CO. USA
1969 MGB Roadster
1987 Jaguar XJ6 VDP
"It's not how fast you go, it's how fast you go fast"
=========================================================
> -----Original Message-----
> From: owner-mgs@autox.team.net [mailto:owner-mgs@autox.team.net]On
> Behalf Of Warren Pruitt
> Sent: Wednesday, August 19, 1998 5:32 AM
> To: mgs@autox.team.net
> Subject: OD Speedo Gear/Pull
>
> I have acquired a '76 overdrive gearbox which I am going to install
in my
> '70 B roadster and was curious about the speedo difference and the
easiest
> way to correct the problem. My understanding is that year gearbox
turned
> the speedo at 1000 revs while my speedometer is calibrated for 1280
or 1240
> (can't remember). Can the gears in the gearbox be changed to the
earlier
> gears and do both gears have to be changed or just (hopefully) the
pinion
> gear? Somewhere I thought I read about a box that could be installed
on the
> cable between the speedo and gearbox that could be adjusted as
needed.
> Anybody know anything about where these can be found and at what
cost? The
> other option is replacing the speedo, but I imagine an instrument
that
> matches my current ones are going to be rare.
> Help appreciated!
>
> Warren Pruitt
> 1970 Roadster
> warren_p@ls3p.com
>
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