12 Volt Positive Ground To Negative Ground

[Mikemomd]

My 48 Dodge D-24 [ by the previous owner ] was converted to a 12 volt system, however, it was kept as a POSITIVE ground system. It has a 12V generator that is working fine.

 

I am switching it to a NEGATIVE ground system tomorrow.

 

Anything I am missing in the following steps:

 

1. Disconnect the battery
2. Reverse the wires on the coil
3. Reverse the wires on the ammeter
4. Reverse the battery cables.

 

Thanks,

Mike

[Don Coatney]

Polorize the generator.

 

[Mikemomd]

Thanks, Don....not sure what type I have [ http://s1276.photobucket.com/user/mikemomd/media/48%20Dodge/Parkersburg-20130609-00270_zps8766bcd7.jpg.html?sort=3&o=0 ]

 

Do I polarize the generator AFTER reconnecting the battery???

 

Mike

[Don Coatney]

You should have autolite as that is mopar. Must have the battery connected to polarize.

[Mikemomd]

Today, I completed my 12 V Positive ground conversion to Negative ground....

 

....along with a tune up: new plugs, spark plug wires, points, condensor, rotor.

 

My buddy came over and check out the timing, finalized all adjustments, checked the compressioin pressure of each cylinder.....100% A-O-K

 

....she runs like a dream and sounds like a symphony.

 

Thanks for the diagram on the voltage regulator....you were right, Don...it's an autolite. Polarizing the generator went without a glitch and checking the generator function out after starting up shows it to be working fine!!

[Don Coatney]

Is this easier than doctoring?

[Mikemomd]

Maybe it's time for a career change ...............  nahhhhh!!! Better stick to my day job so I can afford my evening / weekend "job" !!!

[cheap chad]

Reversing the coil wires??? Some do some don't. Wired for success by Randy Rundle chapter 8 pages 118 to 120... "if you reverse the polarity of your vehicle, you need to leave the ignition coil alone". His claim is by reversing the flow of current in the coil will reduce the output voltage by about 30%.  I took two years of electronics repair back in high school which I believe just confused me more on the subject, HE HE. Although I did find Randy's book well worth the price and easy to follow IMHO. 

Edited July 6, 2013 by cheap chad

[Don Coatney]

Coils are marked with a (+) and a (-) and should be connected acordingly.

[seabee1950]

Maybe it's time for a career change ...............  nahhhhh!!! Better stick to my day job so I can afford my evening / weekend "job" !!!

If you have success in your Day job and the funds are supporting the night & weekend play time, you will be happier, I know for a fact your family will happy you did.

We all need this time to get the weight of the day off our shoulders, and I think there is a real peace in these old cars and aggravation.

[squirebill]

Obviously from the above posts this works OK.  I had thought about doing it to my B1B but somewhere in my far past thought that when you changed the polarity on a DC motor it changed the direction the motor turned.  I was concerned my starter would turn in the opposite direction...thought it would  "unstart" the truck. Learn something new everyday.

[TodFitch]

. . . but somewhere in my far past thought that when you changed the polarity on a DC motor it changed the direction the motor turned. . . 

 

The direction of rotation of a DC motor is determined by the relative directions of the magnetic fields of the armature and of the poles. Since on our old vehicles the pole magnetism is supplied by a field coil, reversing the polarity of the electricity on the system reverses both the poles and the armature so the motor will continue to run the same way.

 

Most modern small DC motors now use rare earth magnets for the poles, so reversing the polarity of the power to them will reverse the direction of rotation as the direction of the armature magnetism is changed but not the field magnetism. This is one place where new and old DC motors act differently.