Why do some old tractors etc have positive ground are the starters and generators "wound differently," I have no clue and always wondered why?

I have a problem that may be related.

I have a 1937 3/4 ton IHC pickup and the starter went bad, the armature? winding broke in one place.
Might this have been caused by my hooking the positive cable and post to the starter and the ground post and cable to the frame when I should have been reversing the set-up as if it were a positive ground.
I haven't been able to find a local shop that can fix my starter in 2yrs (no title etc) and I've found two identical locked up starters and maybe I can make one good one?

Thanks.

 

I have restored a couple of 1960 Triumph roadsters and they have positive ground systems. To keep the stock appearence, I decided to install a radio in the glove box. Installing a negative ground radio in a positive ground car was a real challenge, but it worked out finally. Rebuilding your starter from parts may be your best solution. Good luck.
Dono

 

I remember reading a long time ago about how to change the polarity on your charging system. I think all you have to do is repolarize the generator and naturally, switch the battery cables. I just don't remember the exact details. If you go to a British car site, I'm sure you'll find your answer, as many of the early ones had positive "earth" electrical systems.

 

By far the easiest way to convert it to a negative ground system, is use a GM one wire alternator, and have the starter rewound to allow the correct voltage flow.

 

I can say this much...starters don't know positive ground from negative. We convert old Ford tractors from 6V positive ground, to 12v negative ground all the time at the shop. We do absolutely nothing to the starter, and man does it whip that ol' girl over!! Since it doesn't have to crank very long at all, the starter lives just fine on 12v negative.

In my area there are electrical motor rebuilders that can repair almost any kind of electrical motor or generator. We get most of our rebuilt starters, generators, alternators, etc. from just such a rebuiler. (and we work on a BUNCH of old Ford tractors..) Check around your area for something similar.

 

I had an old Studebaker pickup that was positive ground, but didn't know it when I first got it running, hooked up the battery neg. ground. Started ok, just no charging sytem and the ammeter worked backwards. Then I got my first Sunbeam Alpine, also pos. ground. As Dono said, it can be a challenge to hook up a stereo sytem completely islolated from the chassis. Thought I had it done right, built a wooden console wrapped in vinyl to mount it in, then when I plugged in the antenna wire, ZAP! One fried stereo! Forgot the antenna is grounded! Eventually I just changed it over to neg. ground. Yes, just had to re-polarize the generator and switch the leads on the ammeter, and I think I had to reverse the wires on the coil but I'm not sure...it was quite a few years back!

I don't know why so many vehicles were pos. ground in the '30s, but my dad had a '37 Dodge and a '37 LaSalle that both were, along with a few others. But to answer the original question, I very much doubt that hooking the battery up reversed would have damaged your starter, they're actually pretty tough. My first auto shop teacher would convert old cars to 12 volt neg. ground using the original starters. They spun nice and fast, he said the key was to avoid any extended cranking. His '39 Chevy had electronic ignition and always started the instant he hit the button.

You should be able to find a shop somewhere that can rebuild your starter, around here it seems like every small town has a starter/generator/alternator rebuild shop. I don't understand why they would care if you had a title or not, you're just bringing them the starter to fix, unless you have some screwy laws in Ohio. I would first try swapping some parts around between the 3 starters you have, you might be able to make a working unit unless all 3 have the same exact problem. Good luck, -TD

 

Why positive ground? Years ago I was told it was a Ford invention. When they were designing the model A, they figured that making the system positive ground it would cut down on battery terminal corrosion. History has shown cleaning your terminals isn't that big a deal.

 

Electron flow theory says that electricity flows from negative to positive, so perhaps some engineers preferred to wire it up that way? Think of it this way, electrons, not protons move during current flow. Electrons are attracted to protons, and repelled by one another, so they'd be quite inclined to travel from the area of highest concentration (negative terminal) to the area of lowest concentration (positive battery terminal). So from an electrical veiwpoint, positive ground technically makes more sense.

 

I believe that was the answer, there was and I'm sure there still is questions about
as to the way direct current flows. Up until after the war most all vehicles
were positive ground. I spite of our learning and research I'm sure the opinions
will continue to differ. Generators can be polorized easily to either direction and
I while I haven't tried it would think alternators can be changed by transposing
the dieodes in it. My 2 sense. By the way I had read years ago that Mr Ford
was kind of afraid of electricity.

 

Well we can thank Ben Franklin for this mess. When old Ben was trying to figure out what way Electricity flowed he got it back words. By watching a spark he conclude that flow was from the the point of where the spark started was positive the other end being negetive when in fact the oppisite is true.

In reality for most older vehilces it makes no matter what system you use unless you are planning to add a modern stereo system. All todays designs are negative ground systems.

I think the reason for the change though was saftey and manufaturing cost. Even though a battery will not shock you a running system can in todays monern cars. In the positive ground system all the potential is on ground. Just like water electricty will follow the path of least resestance. If you provide less resitance to the system the electricity will flow through you. This means to use a positive gound system in todays cars they have to isolate from ground anything that you may come in contact with.

 

My Grandfather told me it was because the batteries were not very reliable. There was a way you could hook up the jumper cable(s) and the starter would start to turn over bypassing all the other circuits, so it was easy to jump start a car. Even with one piece of wire.