Datsun Roadster Forum-311s.org

Has anyone tried this method or approach to converting Speedo to GPS? Seems the only caveat is Speedo square drive size and output knurled knob size. I want to keep my gauge original. Seems a cable shop could convert the end to fit the unit via a new Chevy connector. Does anyone see any possible cons to this? Yes I understand there are vendors that do conversions. https://youtu.be/-ZV0ExvV8u0?si=UfZaGKnCNMOwB1u7

Have you talked to Frampton? He does many gauge repairs and conversion/s. He should post some photos of his work. I know it's A++ but I don't know all the options he offers.
The video you listed has some steep pricing.

It's not legal to touch the speedo head since
early 80s must be certified by state inspector
As long as you didn't pull the speedo head , no foul...Pop Secret s my fave brand

This issue more or less came up a while back. (resetting milage on a rebuild) It got a bit heated. Getting my popcorn ready.

My intention is just to accurize the stock Speedo due to tire sizes etc. In no way am I modifying the gauge, it stays original. It’s just a matter of modifying the cable end if the square drive is similar. Guess I’ll just DIY it. Just wondered if anyone’s went this way.

Haven’t done this, but I did recently check function of my speedo with a square drive screw driver bit. Maybe you can mock something up that way…

What happens if the power is cut ...doesn't record miles or speeds ? It would in my opinion/ understanding
So that's a modifying act
Our Nissan used cars get ready tech quit to go work at a car stereo shop, he said working outside in good weather was so much better ( the used car air comp.was deafening )
Cops though were survieling them and booked him and another for possible odometer tampering , they checked and raised one guys prints off the back of the speedo assy., they ended up pleading no contest to the charges , to save $$

redroadster wrote: ↑Sun Dec 03, 2023 9:21 am What happens if the power is cut ...doesn't record miles or speeds ? It would in my opinion/ understanding
So that's a modifying act
Our Nissan used cars get ready tech quit to go work at a car stereo shop, he said working outside in good weather was so much better ( the used car air comp.was deafening )
Cops though were survieling them and booked him and another for possible odometer tampering , they checked and raised one guys prints off the back of the speedo assy., they ended up pleading no contest to the charges , to save $$

I hear you and don't dispute your experience. However, I recently had my speedo rebuilt by a very long term business (Tacoma speedo, 30 years?) and when it came to the odometer they asked me what I wanted it to be (I selected all 000000 to help me track the new motors mileage). I don't know the legality of this, and I would think it it would be federal vs state. I own a very rare car, and some would argue that accurate mileage would be an issue should the car ever come up for sale (not while I'm alive!). Nevertheless, Tacoma speedo is no fly-by-night company and I would think they would be very cognizant of the potential consequences of the law... don't know what to think, but I'll be gone and only a ghost seen on the road to Mt Rainier if it ever becomes an issue!

You think it would be federal vs State ?
It would be federal vs Greg Burrows or that speedo serv the fines are in $$$$$
Fbi has a ask a ? Email

All you 311’s people viewing this specific thread, I worked for two of the largest instrument manufacturers in the world ND Denso, and VDO. One is the biggest automotive and motorcycle instrument manufacturers in Japan the other one of the biggest instrument manufacturers in Europe. What Redroadster is saying does NOT apply. I sold to instrument repair companies in most of the western states, Redroadster is wrong on this and is giving poor advice. When it comes to electronic speedometers sold by VDO to street rods in all 50 states that go through complete inspections prior to the issuing of licenses plates, they have no problem with the speedometers being used. So Redroadster if you want to contact the feds about what I just go for it, otherwise please give it a rest. FYI you cannot change the odometer on electronic speedometer as it will not write over the miles without replace the chip that records the miles.
Dave

Oh brother !! I ( a 30 yr dealership tech multiple asian brands & ase master tech ) am being schooled by hobbiests that can't understand
basic auto electronics ( the way DC current flows , many testing procedures ) and are trying to state there are no US laws that apply to any car mods you feel like doing ,I believe you have heard of them

So now does anyone know if a Chevy, Ford, or Mopar Speedo square cable are close in size to Datsun’s? All I would need to do is modify the trans end of Speedo cable to fit the gps adapter. I have an inclination that domestic cars have a larger diameter cable. Then I’m SOL !

Bill can answer your questions:

https://www.billsspeedo.com/

My previous thread re: adapting Chev TH350 tranny drive to oem 1968 SRL speedo gauge (160 mph):
viewtopic.php?p=306672&hilit=speedo+ada ... en#p306672

Jon

So Jon, Is the below quote from the actual measurements from the Datsun Speedo cable? Because 7/8”@ 18 TPI is exactly the Chevy trans end output connector that the GPS adapter comes with If correct I’m good to go. Sorry haven’t figured out how to hi light quotes.

I had recently replaced the speedo cable on our stock ’69 SRL, so I furnished these measurements to Tom:
5/8”x18 TPI nut at gauge end, 7/8”x18 TPI nut that screws onto the distributor (sorry, Greg, I couldn’t resist ),er, tranny, and 3/16” dimpled Datsun barrel also at tranny end

Yes, those measurements are correct for both Chev and Datsun. If you run into any problems, Bill can help you.

Anxious to hear how it goes!

Jon