Technical Use of a GPS Speedo

I have a 49 Merc flathead and overdrive trans. I am researching the possible conversion from the stock cable driven speedo to a GPS set up but don't know much about them, how they work , how to install one etc. Any info would be really appreciated.

 

First you need an electric speedo as far as I know. Then it is a simple wiring job .

 

i run one. its very simple. they are electronic taking about six wires. there is what they call a antenna. it is about 1. 5 inches square. it is magnetic. it needs a view to the sky. i don't run a hood on my car. i have mine mounted to the fire wall. it works great. the one i use is a autometer with a autometer elect speedo. there is a button that is held down to sync the two and you are done. when the car is first driven each day there is usually a slight delay in getting the signal. its less than a minute. as mentioned above you do need a elect speedo.

 

seems to be too simple

 

I use a free app on my iPhone that is a gps speedometer. I'd bet they have one that's even easier than six wires

 

That is my plan. I have a 49 mercury overdrive installed in my 40 Ford coupe project. The transmission did not come with a speedometer gear and cable .So I bought an Stewart Warner electronic speedometer and I bought a speedway GPS gauge pulse generator. Part # 910-97710. It is supposed to be as easy as racer-x says.

I see one possible problem is that the electronic gauges are very sensitive to ignition pulses from your spark plug wires. You must use resistor or suppressor spark plug wires.

 

i use my speedometer app on my android phone and it's extremely accurate!

 

Me too.

 

I changed the rear end in my 53F100 and the speedo [mech] is way off. So I use my Garmin stuck on the windshield until I install new gauges. Hey Duncan, do you tape the phone to the dash? Just had to say that.

 

It can be even easier than that. There are electronic GPS speedo's all in one piece, stupid easy to use and deadly accurate. I used one on my V8 OT trike, loved it. There is a huge selection of faces, pointers, options (1/4 mile ET, high speed, avg speed, 0-60, etc.) Here's a link to a basic, traditional looking speedo with a one-plug three wire hookup. http://www.speedhut.com/gauges/GPS-Speedometers-2-5-8-inch/1:3|37:2

 

I have one in my OT Vette. It just wires up power ground and antenna. I have the antenna in the corner of the dash. Small square box.

 

My car was a mocked up rolling chassis/"A" roadster body when I got it. Had a SW mech. speedo in it. The trans I used (Ford toploader 4spd) had the speedo drive on the right, meaning that the cable would have to get over up fron from right to above steering column to speedo. I also had no idea what drive gear was on the output shaft. Gonna be a real pain in the ass, I thought.
Then I found the Speedhut setup. It cost me less than buying an electric speedo and driven unit a, etc.
The Speedhut web site helps you customize the dial of the 3-5/8" face to look just like that on the rest of the SW gauges. You block off the speedo drive opening in your trans., hook up wires to the speedo unit for lights, a hot and ground and pug in a plug from the antenna, also a magnetic 1.5X1.5" piece about .375" thick , in a plce where it can pick up the satellite. That's it!!!
It also will give you an odometer, altimeter, 1/4 mile et & speed, and 0-60mph time.

 

I have a classic instrument spedo. I installed a gps sender also from classic instruments about 1 year ago . I used a l bracket inside the firewall with gps aimed through the cowl . works like a champ. It has no transmission connection at all.

 

Leave it original looking and then just use your smart phone with a GPS speedo app. It is by far the easiest way to go. Then you can just rig something up to hold your smart phone.

They work off of satellite location and sometimes if there is a strong enough solar storm they don't work worth a flip.

 

Porkbeaner is right about the gps antenna, sometimes they don't work. I have the Classic Instr. one in my 40 and there are times it does not work.

 

I was reading a thing on solar storms in Nat Geo a while back. I knew that GPS survey tools would got off sometimes and they always said sun spots. Anyway I guess when there is a big flare it moves the satellites around and if the satellite is not in the right place the GPS will be off.

 

Other than solar storms, I guess you have to avoid tunnels too...

 

At your age, you should stay away from speedos...

 

I have a garmen, sets on top of the under dash ac in my pick up has speed, speed limit and time. You can type in an adress ans it will show you the way tell you when you will arive.

 

I'm using a "SPEEDHUT" unit on my 29 P.U., works great all the time the pickup unit is magnetic and sits near the windshield, very easy install

 

I'm using all Speed Hut gauges and there GPS Speedometer .... work perfect all the time and they will make you what ever you want.