Convert mechanical speedo to electronic?

Snail50

Founding Member
Mar 24, 2001
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Miami
Okay, I'll be the first to admit that I don't know a lot about mechanics & electronics, so pardon moi if this is a boneheaded question (like "can I run diesel in my gas engine?").

Anyway, I'm getting ready to build a new gauge cluster for my 67, but the speedo I want to use only comes in electronic system, and not mechanical.

Is it possible to make an electronic speedo work in my car; if so, what is involved?

I'm not dead set on using that specific gauge, so if it's possible but prohibitive and costly, I can reconcile myself to using a different gauge.
 
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You can make anything work... it just all depends on how much time and money you want to put into it.

Newer vehicles use a speed sensor (also controls ABS).

You do not have this sensor, and installing one is no easy task.

There are guages that use a mechanical input (cable) but show a digital display.

You may be able to get a "sending unit" that the cable would hook up to and provide a signal like your guage requires. (I think it's just a voltage that climbs with speed, but don't know for sure. Could also be a pulse that increases in frequency with speed).
 
The speedo sending units arent terribly expensive (I guess it depends on your defintion of expensive) and I beleive they work on pulses.

Whoever you are buying your guages from should also have a sending unit availible.
 
thanks for the info. I'd probably get the gauges from Summit, and they'd likely have everything I needed.

So the mechanical speedo cable would plug into the sending unit, which in turn would send an electrical pulse to the electronic speedo?

By expensive, can you guys give me an idea of $? I'm not poor, but I'm not Donald Trump either. For instance, I don't want to spend $10K retrofitting a computer into my 67 just so I can have an electronic speedo...
 
I have an Autometer Phantom series electronic speedometer and I'm using autometer's electronic sending unit. It plugs into the tranny where the old cable did, and it also uses the old speedo gear. The neat thing is that you can recalibrate the speedo anytime. You just push the odo tab, mark off a 2 mile distance (I did this on the freeway at night) start at one end and stop at the other. It takes a whole 5 min to recal the speedo after gear/rim/tire changes.
 
cstang68 said:
I have an Autometer Phantom series electronic speedometer and I'm using autometer's electronic sending unit. It plugs into the tranny where the old cable did, and it also uses the old speedo gear. The neat thing is that you can recalibrate the speedo anytime. You just push the odo tab, mark off a 2 mile distance (I did this on the freeway at night) start at one end and stop at the other. It takes a whole 5 min to recal the speedo after gear/rim/tire changes.

That sounds like a plan, I don't think I've ever had a hotrod with the right setup in it :D I was just gonna run a tach in my 46 and clock it, but that sounds like the easy way to do it :D
 
I just did this swap a few weeks ago when I put everything back together. My tranny needed the standard pulse sender (Autometer part# 5291) since it is a GM based tranny. They also have a Ford style (part# 5292)

Part# 5291
atm-5291.jpg


Part# 5292
atm-5292.jpg
 

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2bav8 said:
Yup,

I used the 5292 sending unit along.

Okay, that's the one I'd have to use for my C4. According to Autometer, it's called the "Hall Effect Sender."

I downloaded a diagram for Autometer's site, and it looks like the 5292 sending unit screws into the transmission at the point where the speedo cable would go, then it has to be wired to Ground and into the 12V ignition source, and then the 12V source and signal wire go to the speedo. If there's more to it than this, let me know.