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Old 12-20-2014, 11:36 AM   #1
southfork
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Default Is Positive Ground Better Than Negative?

I've been wondering about the positive vs negative gound question and why our old Fords were mostly (or entirely) positive ground. All my old Fords are wired with positive ground (except one) while my newer daily drivers are all negative ground. Why did Henry use positive ground in the old days, and why did he switch to negative ground later on?

Also, why did he wire some negative ground in the early 1940's? Specifically I have a Ford 9N tractor that is negative ground, and an 8N tractor that is positive ground. All of my Flathead V8 engines IIRC are positive ground.
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Old 12-20-2014, 11:43 AM   #2
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Default Re: Is Positive Ground Better Than Negative?

In electrical engineering circles of the day, it was agreed that the way the electrons flow made positive earth more efficient. When dealing with 6-volt systems you need every advantage you can get. Any form of degredation in the OEM system circuitry will lead to problems so they have to be maintained in top condition to work well.

The N series tractors ony have a rudimentary system so it would likely work just as well either way.
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Old 12-20-2014, 12:14 PM   #3
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Default Re: Is Positive Ground Better Than Negative?

It's not just Ford, a lot of the early cars used positive ground. Because electrons are negatively charged and the thought was the electrons move through the wire it was thought that electrical circuits should be wired so that the electrons could move from the negative side of the battery through the circuits to the positive ground. Over time it was determined that the concept of holes moving (an electron missing to leave a positive charge) worked for circuit design. This gets a little complicated as to what is really going on, but that is a somewhat cartoon version!
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Old 12-20-2014, 02:59 PM   #4
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Default Re: Is Positive Ground Better Than Negative?

Positive ground is better if you want your battery gauge to work right. I found that out after I got my car back on the road that had sat for 31 years. Knew nothing of positive ground so when I put a new battery in I hooked it up negative ground just like all my other cars. Everything worked fine except the battery gauge worked backwards - showed charging when it was discharging and vice-versa. Knew no better until I had the engine rebuilt and the mechanic said, "Bet your battery gauge has been working backwards. . . . That's cause you've got your battery hooked up backwards."
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Old 12-20-2014, 03:20 PM   #5
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Default Re: Is Positive Ground Better Than Negative?

I'm surprised that you could get away with that backwards hook up of the battery with no difficulties other than the guage working backwards. If that's the worst that it can do, I think that i'll try hooking up the battery backwards on my 1940 Ford 9N tractor, and see if that helps it start better than it currently does with the negative ground hook-up.
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Old 12-20-2014, 03:22 PM   #6
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Default Re: Is Positive Ground Better Than Negative?

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Quote:
Originally Posted by southfork View Post
I'm surprised that you could get away with that backwards hook up of the battery with no difficulties other than the guage working backwards. If that's the worst that it can do, I think that i'll try hooking up the battery backwards on my 1940 Ford 9N tractor, and see if that helps it start better than it currently does with the negative ground hook-up.
Don't forget the coil.

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Old 12-20-2014, 03:37 PM   #7
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Default Re: Is Positive Ground Better Than Negative?

I heard rumors back in the 50s that was because they all went to 12V so as not to confuse anyone they also went to neg ground. I said IT WAS A RUMOR noting in writing.
When I got my 34 5W in my avatar the P O was sooo thrilled because he had rewired it. Slight problem tho he used 12V cables & wires & neg ground. Did not change anything from 6V to 12V. He also placed the battery in the trunk behind the driver seat. Could not figure out why the battery wouldn't keep a charge & the halogen headlight were always dim.
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Old 12-20-2014, 04:05 PM   #8
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Default Re: Is Positive Ground Better Than Negative?

Quote:
Originally Posted by southfork View Post
I'm surprised that you could get away with that backwards hook up of the battery with no difficulties other than the guage working backwards. If that's the worst that it can do, I think that i'll try hooking up the battery backwards on my 1940 Ford 9N tractor, and see if that helps it start better than it currently does with the negative ground hook-up.
The 9N was positive ground from the factory. If you go back
you will need to polarize the generator, no big deal.

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Old 12-20-2014, 04:25 PM   #9
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Default Re: Is Positive Ground Better Than Negative?

I have never seen a 9N Ford that was NOT Positive ground. Make sure you have a good shiny surface where the starter connects to the motor & use 00 battery cables (assuming your still 6 volts).
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Old 12-20-2014, 04:47 PM   #10
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Default Re: Is Positive Ground Better Than Negative?

Quote:
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Don't forget the coil.

Charlie Stephens
My coil worked just fine either way.
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Old 12-20-2014, 05:08 PM   #11
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Default Re: Is Positive Ground Better Than Negative?

coils will get hot if there hooked up wrong
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Old 12-20-2014, 05:16 PM   #12
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Default Re: Is Positive Ground Better Than Negative?

When I bought my 8N the previous owner had replaced the ground from the battery with a new cable( 12 volt skinny plastic covered,imported), I went and got a nice 1 in wide 1/4 in thick woven flat ground cable, now starts up in less than 1 full turn.
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Old 12-20-2014, 05:30 PM   #13
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Default Re: Is Positive Ground Better Than Negative?

A long long time ago I read a British article that said it was better to have positive ground because somehow it helped prevent body corrosion. Many British cars were 12v/ PG. Judging from the many British cars I had in my youth, it didn't work.
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Old 12-20-2014, 07:04 PM   #14
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Default Re: Is Positive Ground Better Than Negative?

I also had 2 Triumphs and a Jag all 12 volt and positive ground. Like Ross F-1 said, didn't solve the rust problem. The Brits called it positive earth.

Last edited by 42guy; 12-20-2014 at 07:07 PM. Reason: add word
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Old 12-20-2014, 07:22 PM   #15
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Default Re: Is Positive Ground Better Than Negative?

Quote:
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My coil worked just fine either way.
They will work if wired up wrong, but they will not work "just fine" that way!
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Old 12-20-2014, 08:00 PM   #16
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Default Re: Is Positive Ground Better Than Negative?

Is there an easy way to tell if an old Ford is still positive or negative ground if you acquire one and the battery is missing? I bought an old Model A and don't know if someone converted it to negative ground or not.
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Old 12-21-2014, 03:24 AM   #17
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Default Re: Is Positive Ground Better Than Negative?

34pickup, If the battery cables are still on the car, just see which one has the larger opening for the battery post. The positive post on the battery is bigger than the negative post so is easy to see which is which.
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Old 12-21-2014, 07:39 AM   #18
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Default Re: Is Positive Ground Better Than Negative?

Quote:
Originally Posted by Ross F-1 View Post
A long long time ago I read a British article that said it was better to have positive ground because somehow it helped prevent body corrosion. Many British cars were 12v/ PG. Judging from the many British cars I had in my youth, it didn't work.
I've heard that too, Over here we had 12 volt mostly from about 1950, but positive earth (ground) till about 1968 ish.
Maybe coincidence but an observation. Over here (Britain) there are far more mid to late 60's and earlier cars on the road than late 60's through to mid to late 80's, these later cars dissolved pretty much while you looked at them!
So possibly some truth in that?
As I said, just an observation.
Martin.
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Old 12-21-2014, 07:46 AM   #19
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Default Re: Is Positive Ground Better Than Negative?

I have always understood the reasoning to be that the battery was less susceptible to corrosion and the old cloth covered wires were less susceptible to static discharge thereby causing connection/corrosion problems where wires touch metal.
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Old 12-21-2014, 08:18 AM   #20
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Default Re: Is Positive Ground Better Than Negative?

If there was a significant advantage to pos earth (ground) over neg earth, then all manufacturers of cars would have taken that advantage. You wouldn't universally switch over to negative earth if positive earth gave an advantage.

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