electronic speedometers

[autocol]

stupid question coming up!


how do electronic speedometers work? do they just accept a pulse from the box or do different senders require different speedo units?

basically, i have a toyota supra gearbox in my ute, which was originally part of a conversion that included a mechanical speedo drive out of the usually electronic spot. then i blew that gearbox up, fitted another one in a rush, and haven't had a working speedo since (because the new box wasn't modified for the mechanical drive).

now i want to whack a new set of guages in, and figure i might as well convert to an electronic speedo... any complications ahead for me?

[paul2748]

From what I remember when I installed an electric speedo on my flathead T, there are two types of electronic speedo.  One has a pulse system, the other I can't remember what they called it.  I've used VDO in two cars, my son's 302 powered model A and the T.  Very easy to hook up as long as you have directions.  I don't know about interchangeability between the two types, but I think the VDO speedo could run on both types - the wiring was a little different.

[Fat Cat]

how do electronic speedometers work? do they just accept a pulse from the box or do different senders require different speedo units?

Basically the answer to that question is in answered by your next statement. There are a couple of different pulse ratios. The most common are 4 & 8 pulses per revolution. GM USA on some cars acually used a speedo that took 8 pulses and a cruise setup that only needed 4 pulses. They used on pulse generator and placed a signal splitter on the line with a 8 pulse and 2-4 pulse outputs.

If you can find out what you trans signal generator outputs and match the gauge to you you should have no problems other than running wires to it.

[autocol]

cool. sounds easy.


thanks.

[unklian]

Nothing is easy anymore.

How about an electric speedo with a pre-electric transmission?

[enjenjo]

You can buy signal generators the replace the speedo cable.