Stovebolt.com Forums The Shop Area Interiors Original speedometer with modern transmission.

Has anyone here made a solution to keep their original speedometer when changing to a modern transmission?
I wanted to keep my original speedometer so I looked at several solutions. I’ll be using a 5LM60 transmission with NP241 transfer case so the speedo signal is not cable driven. I could have the transfer case modified to accept a cable drive. I could get a speedometer drive module, a couple companies make them. I could modify my speedometer with guts from a modern speedo, stepper motor. I decided to DIY a solution. I had read about mounting an electric motor to the back of the speedometer, but how to do that. I thought it was a dumb idea to put the motor directly on the speedo, remotely mounted with a cable is a better idea. I read some more and found few examples. I finally decided to try mounting a motor directly to the speedo. I have been working on this project for a year and thought I would share my test run here. Here is a link to a video I made: https://youtu.be/K6YOm1WTpqg

Well...sort of. I converted a Speedhut electronic speedometer to work with my T5 and keep as much of the original look as possible. This was 2~3 years ago and the work is still here somewhere. You can make the work I did easy as pie if you want to use the Speedhut global positioning speedometer (size and everything is the same) but I didn't want to have the GPS sensor up on the dash or somewhere. You can also see where I combined an S-10 speedometer (electronic but with a digital odometer), a vacuum gauge and a tachometer plus turn signal indicators to fit in the AD speedometer circle.

There is a sticky at the top of this section where you can see both of those speedometers I mentioned...

"I could get a speedometer drive module, a couple companies make them. "
This is an easy way to get a correct speedometer reading.

If you need names of sellers, just ask.

I like that S-10 speedometer with the extra gauges, Jon. Tim, I’m aware of the various options for an off-the-shelf solution. Abbot’s Cable-X, Dakota Digital, Speedhut, there was also Dragonaero but I think that may have fizzled. I found an epic discussion on another forum where someone was building a unit where the motor mounts directly to the back of the speedometer. That discussion spans 3 years, and ends with nothing. I decided to try this myself, and it works well. The video was to show how it compares to a stock speedometer in my ’90 truck with the ‘50s speedometer sitting next to it, wired into the truck. Not the best video, but it does show enough to get an idea of needle movement and tracking.

Thanks Walter. The S-10 speedo is unique, all right. I've decided it was a little busy, but I haven't given up on the idea entirely. I've been thinking of adding a vacuum gauge in the center of the other (left hand side) gauges with the background plate the same beige color so it wasn't obtrusive. That gauge in my opinion is more important than a tach for the 235 especially in a pickup. Several years ago (80s actually) a friend made one that would illuminate a green led for good, a yellow led for ok and a red ok for not good. I meant to get his circuit, but never did. The nice thing about it was you saw the leds in peripheral vision so you weren't constantly peering at the gauge.

I couldn't tell exactly from the video. Does your adaptation use a stepper motor?

I read about using a vacuum gauge to troubleshoot and tune up, maybe it was on this site? It sounds interesting. I am using a dc motor with an optical disk, so no, it is not a stepper motor. I did have it setup like a stepper motor for the slow speeds before I implemented the PID code. Turn the motor, pause for 15uS after 3 holes, 64 holes on the optical disk. This allowed the motor to turn the speedometer at 1mph. Now that is done with the PID code. Otherwise, the motor would start at around 10mph.

The jegs style speedo drive box or cable X always seemed to be a easy fix for stuff i put together. Im just about to use one in another stovebolt that I’ve been helping work on.

I had read about the early cable X units having issues at the slower speeds, maybe they have worked the bugs out with the newer versions. Barnfind49, how do you find the cable X to work at the slow speeds? I’m considering changing my code to start the motor in open loop mode and then switching to the PID code after 5mph. Currently the needle jumps at start, the PID compares the previous reading with the current reading, so comparing stopped to moving. I think if I get the needle moving first this will eliminate the jumpy start.

I dont have one on my personal truck because im still running a 319 trans but the last car I set up with one with a t56 trans seemed to work great. I haven’t talked to him in a long time so no complaints. I will be setting one up with a 4L80 in a 50 chevy pickup in the next few months when we get to that point.