1951 WD Wiring Mess


Hello all, I have a 1951 WD project that I could sure use some help with. The battery does not charge, but the tractor runs very good until it has been started enough time to drain the battery. It has a 12v battery, positive ground and has a distributor with a coil with the resistor built in. The generator has a 2 post cut-off switch mounted on it and the post in the right has a wire going to the A terminal. The left post of the cut-off has a wire running up by the battery box and the F terminal on the generator is also running up to the battery box and both of these wires have been cut off and taped. There are no lights or gauges on the tractor, but there were lights at one time because there are wires on the fenders. Can I wire this to work with what I have, or do I need to start looking for other parts? Sorry, I'm not much for electrical wiring. I'm sure I left out some important information. Thanks for any help or suggestions.
The generator/cutout system is for the 6 volt system. Since you now have a 12 volt battery, your easiest and cheapest route (in my opinion) would be to change it to negitive ground and switch the wires at the coil and replace the generator with an alternator.
Thank you for the reply. Is there a wiring diagram for an alternator somewhere? And how much trouble is it to make a bracket for the alternator? Thanks again.
There are lots of somewhat universal wiring diagrams that can be found online. Brackets are easy to make or you can buy a bracket kit premade. For the alternator, I would suggest a 10si delco, commonly known as a one wire. They usually run less than $100 for new, cheaper at a salvage yard. Parts stores will ask year, make and model for one. Just tell them a 74 Chevy C10 pickup with no a/c and you would get the right one. this site also sells an alternator conversion kit and brackets as well.
You have been given a little misinformation on Delco 10si alternators. It probably would have come out in the wash when you started looking at diagrams. A Delco 10si as it was used on many GM vehicles in the 70s and 80s is not a ..one wire.. alternator. In stock automotive form such as the application of a 74 Chevy pickup it is a 3 wire internally regulated alternator. In the 1st link is an example 10si alternator. On the side you see a rectangular plug hole with 2 spade terminals in it. Those 2 plus the stud terminal on the back make up the 3 wires that are connected to make it work correctly. The two spade terminals are on the internal regulator, they are marked 1 and 2. Number 1 is the ..excite.. circuit which has to be powered to to start the alternator charging and 2 is the ..sense.. circuit that tells the regulator the voltage of the system for regulating the amount of charge the alternator is putting out. Even though in most automotive applications that wire runs back and senses voltage back at the fuse box on these old tractors it is simply connected to the output terminal on the back of the alternator an works fine. The wire off the output terminal runs up to the ammeter and then the opposite side of the ammeter goes to the battery so, that terminal on the back of the alternator always has power.
To achieve an alternator that is truly a ..one wire.. alternator a special voltage regulator is installed and the two spade terminals are covered. If you web search ..one wire tractor alternators.. I am sure you can see examples of these. I have never dealt with them but it is my understanding that some of them require the engine to be revved to wide open for them to initially start charging. A 3 wire alternator works just like one in you car, you start it and it immediately starts charging at an idle.
I am attaching a YT archived post that gives wiring diagrams for a WD45. I am not an Allis guy but I would guess there is not a lot of difference. The top diagram is how I like to wire them. Their diagram shows a 10 ohm 10 watt resistor in the excite circuit. That can also be a dash bulb wired in series or a diode. We can get into those specifics when you get to that point. Those have to be in there or the tractor will not shut off because it will continue to run on the output of the alternator. They also show diagrams utilizing an ..Accessory.. terminal type ignition switch. The separate ACC circuit feeding the excite circuit lets the tractor shut off because it is separated from the ignition circuit but powered when the key is on.
One last thing, due to the heavy internal diodes alternator used to convert AC current to DC the alternator has to be connected to proper polarity. Make sure you connect the battery negative ground or you will either let the smoke out of the alternator or your new wiring job.
Example alternator

YT post with diagrams
Thank you for your help. I think I have it figured out. I'll keep a fire extinguisher handy just in case.
Now that is confidence!!! Just kidding. Good luck. I think I would start from scratch and replace the whole show with 12v conversion. Pretty easily done.
I had an original wore out wire harness from a WD and made a new one with approximatly correct length. With headlights and a wire for back lights there is a total of 5 wires-three without lights. Besides the battery cables one feeds the switch, One from generator to ampmeter and one to coil and everything works fine and no smoke. If you have old cutouts and light switch activated charging or bad componets then things can get complicated?? I don't think it has to be complicated???

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