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:
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.
~ Jon 1952 1/2 ton with 1959 235 | T5 with 3.07 rear end
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?
~ Jon 1952 1/2 ton with 1959 235 | T5 with 3.07 rear end
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.
I kept the stock needle and look. I removed all the guts out of the speedometer / odometer. bought a 270 degree sweep electronic motorcycle speedo. 2 inch in diameter. cut off the front. removed the old needle added the original needle flipped upside down. drilled two holes in back of stock speedometer housing and mounted it upside down. fit like a glove. then adjusted the settings to match the output from transmission (6L90). it was off a little bit at max setting so I bought the taximeter adjustment module for speedometers from a taxi meter repair shop in NY. it was 25 dollars and does the same thing the dakota digital one does for a quarter of the price. I was able to get the settings spot on from 5 miles a hour to 85 (cause that is as fast as I am going with bump steer and the slop) lol only thing you loose is the odometer. I put in a fake one with the year of the truck as the mileage. We have a electronic device we attach to the odb2 port if we want the current odometer and other information not provided by stock gauges. I am all in for less than a 100 for speedo/ taxi adjuster and shipping. I'll dig up my parts list form my purchases and see if I can get the models posed here. maybe find my pictures of build
VTWIN39-0464 2 Mini Electric Speedometer was the speedo I used. upside down it has the correct sweep. its autosensing resetting. so you don't use full sweep. once installed the needle taps the end points inside the housing and resets its start and stop points. Very handy for it when you make adjustments and disconnect battery etc. It comes with light when powered. I left it on to give more light on gauges but you can cut the wire and not have the light glowing inside the gauges.
only stock item reused was needle support and alignment bracket off old speedo. I got a new needle this one is my mess around with till i got it worked out. the extra holes in housing was also just me experimenting with different angles.
as you can see it is the exact depth needed for needle to be in gauge housing correctly and if you use the old bracket as you can see the back plate will mount and line up clean.
it takes the feed off of the vss signal from the transmission to ECU. I just tapped into the wire feed. this feeds into the taxi splitter. I just set the pulses in half. Then it feeds speedo. only other wires needed are power and ground. (plus the button attachement for adjusting) This makes for easy calculations. the setting on the speedo is electronic so you can adjust as needed. we used a gps speedo. rolled down the rode and then made adjustments till it was spot on across all ranges. here it is installed. this pic does not have my fake odometer 1956 year of truck cover.
That looks good. I have read a few variations on that type of mod and considered doing that myself, but I wanted to keep the odometer. I saw in my ’88 truck there is a small motor for the odometer, so it could be done.
I have a 1938 1.5 ton speedometer. Are y'all saying we can change out the guts to work with (in my case) something like the nv4500? Sorry I am totally new at this kind of thing but would very much like to stay original.
'38 1.5ton; "The stuff is as tough as woodpecker lips"
The real issue I had finding the right parts was a odometer over needle. Most of any modern one has odometer under needle. And the ones i found over were wrong sweep. And on top. So I went with what worked for sweep and even flipped it upside down. What I found in “making “ one is that the setting for right needle placement on mph is not actual in its memory so the odometer is off. Almost half in my case. So they would have to be separate devices. If you want true stock odometer / speedometer then the cable motors devices are about your only option.
I have a 1938 1.5 ton speedometer. Are y'all saying we can change out the guts to work with (in my case) something like the nv4500? Sorry I am totally new at this kind of thing but would very much like to stay original.
You could gut your original speedo, or you could attach a motor to the back of the speedo where the cable goes, or you could buy a converter box that has a motor and attaches to the speedo with a cable. I decided to build my own and attach a motor to the back of the speedo, it works well so far.
