Re: [DML] Fw: Speedometer cable

["Walter" <Whalt@xxxx>]

I've thought seriously about making a digital speedometer for the Delorean
from scratch. I thought about it off and on for a few hours and finally
figured that it wasn't worth the trouble.

What I wanted to accomplish was to eliminate the angle-drive and come
directly off of the center hub with a 'squirrel cage' optical cylinder.
Shine an infra-red LED & pickup through the cylinder and count the pulses.
I originally got this idea as a replacement fix for broken angle-drives.
The guts of the speedometer gauge would be replaced with a galvanometer and
then work like many modern cars. From the outside, everything would look
original and also be maintenance free.

That would accomplish what I want except for running an odometer. Without a
mechanical connection from the front wheel, there is no way other than a
servo-motor to run the odometer. And I figured that a servo-motor would by
far worse than any angle-drive!

Back to the drawing board....

Then I thought about going entirely digital with the odometer. It could
extend the main odometer out to another digit to count miles by the 100K's,
and then have two trip odometers -- one for trips and one for oil change
reminders... and oh, yeah! -- another one for Lambda sensor maintenance.
All adjustments could be made through the OEM trip-reset knob. But then
that's probably getting too fancy.

I started thinking about how to build the logic circuits.... that would
require non-volatile RAM. I wouldn't want the car to forget how many miles
it had on it only because a watch battery went bad.

Then I thought about adapting something out of another car. I've seen
plenty of Fords with digital LCD odometers. But manufactures like to keep
the workings of those things mysterious to stop people from trying to roll
the mileage backwards. But on all counts, I think this is the way to go --
either to make something work from another car or to build something very
similar. Ideally 'we' could produce a replacement speedometer 'drop-in'.
It would replace the angle-drive with a 'solid state' unit. It would
replace the speedometer cable with a wire, and the gauge would look
identical except for maybe a higher full-scale reading. An LCD or LED
odometer could be put in the little window where the OEM mechanical ones
used to be. As a high-tech extra touch, a larger 3 digit display could be
put somewhere on the speedometer face to show MPH in addition to the analog
display.

Then I thought the best solution would be to replace the whole binnacle
instrument cluster with a cut down lap-top computer LCD display. Then you
could change your gauge layout at the click of a mouse. I figure there is
enough room on the console to keep a mouse-pad, but then how do I stop it
from moving around when I turn corners? Maybe a track-ball would work
better. I could run it all off a lap-top computer with a TV tuner card
installed. Then I could turn part of my dash into a mini-TV set. Is there
any way to get motorized rabbit ears to pop out of the driver's side air
scoop? Imagine! A Delorean based on Microsoft Windows! What a disaster!

Ah, my mechanical speedometer doesn't seem that bad now. I kind of smile
when I see it pulse and fluctuate between 10 and 15 MPH. If I built and
debugged a digital dash for my Delorean, I probably wouldn't get anything
else done in my lifetime. It would probably be just as well to make
mechanical angle-drives from scratch.

Now back to designing those dies to stamp out new stainless hoods!
Tolerance on those things are so tricky.

Walt Tampa, FL