Tony,
Well, mine has never been that horrible..but I haven't
changed gears on that car. Steve is probably
calculating the field stength as we speak! My other car
has a T-5 and after getting it all installed and
fiddling with the speedo for a week, I came to the
realization that the one T-5 that I have in there is
probably the only one in the world that somehow does not
have the speedo drive gear in it!! MY solution in that
case is very similar to yours, I bought a VDO electronic
speedo and built an opto-coupler sensor I mounted on the
differential that senses some tabs I put under the
driveshaft bolts. Works great and IS ACCURATE. Not
exactly stock but either is the rest of the car!
Hacksaw Gary
> My 0.02:
>
> Wow! This is a horrible problem. I've had that critter apart and would
> rather do anything than try to "recalibrate" a magnet. Several variables
> come into play (think age -- bigtime!):
>
> What's the original magnet field strength in Gauss?
>
> How many Joules in a capacitive discharge through the magnet does it take to
> get it to where it belongs?
>
> How do you measure what you've got to start with? And what you're finished
> with?
>
> What's the precise distance from the "cup" attached to the needle-spring
> assembly to get the right coupling?
>
> What's the restoring force in the spring that's needed? (It's really old--
> that's got to be a fun measurement).
>
> Since I'm in a ground-up restoration mode (my speedo crapped at about
> 130,000), my thinking is more toward a well-known set of gears off the
> tranny driving a rotary digital shaft encoder, then counting the pulses. In
> other words, all electronic, pretty much what (I think) more modern
> instruments do.
>
> Anyone interested?
>
>
> ----- Original Message -----
> From: <garywinblad@attbi.com>
> To: "Steve Laifman" <SLaifman@SoCal.rr.com>
> Cc: "Tiger List (Tiger List)" <tigers@autox.team.net>
> Sent: Monday, September 16, 2002 7:02 PM
> Subject: Re: Speedometer gear - got one for 3.07s
>
>
> > Gary,
> >
> > While your advice may be consistent with aged parts,
> it is not
> > consistent with completely re-calibrating the
> speedometer needle for a
> > new gear train. That was the intent of the previous
> posting.
> >
> > Steve
> >
>
>
> Well, yes that is true.. it only addressed the re-
> magnitizing problem.. I don't have a magnitizer handy on
> my workbench.
>
> Gary
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