changing 6volt positive ground to 12 negative ground

59-641-D

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in working on a friends 56IH 350. the tractor is 6volt positive ground as most 6volt is. he wants to change it to 12volt. I know the generator has to go. Is changing polarity from positive to negative affect the starter? Im also aware the coil has to be changed with a 12volt coil with a resistor. anything else???? changes to wiring??

thanks,
Eddie,
 
Polarity doesn't matter to the starter and 12 volts won't hurt it.
Use the same coil, just add a ballast resistor and switch the small wires on top of the coil.
Change the light bulbs to 12V.
Reverse the wires on the back of the ammeter.
A good auto-electric shop should be able to change the genny to 12V.
 

He already has the alternator, I just have to mount it. eliminating the external regulator (alternators already have one built in) Ill probably have to make some modifications to the braket.
 
The whole point of going to 12V is to get rid of the maintenance-intensive, unreliable (due to lack of maintenance) generator.

Why would you pay $100-$200 or more to have the generator converted when you can get an alternator for $30-$40? Yeah it's not "original" but neither is 12V.

If you get a one-wire alternator, wiring is simple:

1. Move the wire from the GEN terminal on the regulator to the BAT terminal on the regulator. There should be two wires there now.

2. Connect the wire you removed from the A terminal on the old generator to the BAT terminal on the new alternator.

Of course, you also need to reverse the ammeter leads and install a 12V battery negative ground as you normally would.

Basically my scheme just bypasses the regulator and gives the alternator a straight shot to the ammeter, which is exactly what the alternator needs.
 
The starter is an electromagnetic field type NOT a Permanent Magnet so it will still turn the same direction regardless if Polarity is reversed. I've used plenty of 6 volt starters at 12 volts with no problems HOWEVER it can be a bit tougher on starter drive mechanisms. I've also successfully used 6 volt gennys to charge 12 volts simply by changing to a 12 volt Voltage Regulator BUT BEFORE ANYONE HAS A CALF it didn't set the world on fire as far as charge rate and its possible the fields might overheat and its NOT engineering correct Im ONLY saying it worked so Billy Bob can calm down now lol. A genny shop can change fields and convert it to 12 volts or else just get a 12 volt genny and VR.

You can keep the 6 volt coil and just add an external series voltage dropping (12 to 6) Ballast resistor or else get a full true 12 volt coil no ballast required.

Coil polarity would be switched if you change polarity.

If it has an ammeter and you change polarity its leads need reversed.

12 volt lights.

Be sure to Polarize the genny BEFORE start up.

If I missed anything hopefully other gents can add more to this

John T
 
One can simplify the conversion from generator to alternator, by purchasing a 6V alternator. I purchased one from J C Whitney and installed it onto a cub, retaining 6V lamps etc. It worked very well.
 
Got kind of a 'sub-question' here...

6volt systems are typically + grnd and people change to - grnd when changing to 12 volts. My question is...

Why the change in polarity? What would be wrong with a 12volt + ground system? I imagine Prof. John T. will educate me...lol!!

Thanks, Rick
 
Since alternators became standard on automotive applications the alternators have all been for a Negative ground system. We had a customer that had an 1800 Oliver and he hauled large wagons of tomatoes with it at night. This was in 1964 and we converted it to a 12 volt positive ground alternator so the charging system could handle the extra lights on the wagons.
 
A little knowledge can be a dangerous thing, but here goes anyway.
The way I see things, the change to 12 volt batteries & high tech accessories happened close to the same time, not by plan, but by coincidence. Early 12 volt autos still had tube type radios etc, so could be either polarity. By nature of the beasts, transisters & high capacity diodes use the neg pole as the heat sink contact. It is an electronics industry standard. With the addition of more electronics it was more economical to make the vehicle polarity to match. Also makes sense to have that big aluminum, exposed to the air, heat sink at the same potential as all the metal parts nearby.
IIRC, Mr Kettering, the guy that invented coil/points ignition decided to run GM cars at neg ground.
That"s my story & I"m sticking to it, unless someone can show me I"m wrong again.
Willie
 
With a coil/points/spark plug system, you actually get a very-very-slightly stronger spark when using a positive ground (a 12V difference when compared to a 40,000V spark). The difference in spark intensity due to this ground potential is small, but engineers cannot resist even a miniscule benefit. Things changed when transistors came out, due to heat sinking/reliability/product life/practicality reasons (see the next post). As a result, the small increase in spark intensity was no longer a free benefit, but a disadvantage.
 
you're eliminating to external regulator, Most alternators have an internal regualtor. As to an update, the modifications for the alternator to bolt in are interesting. I have to shift the alternator 3" forward of the original postion. with some threaded rod, bushings cut to size, this should work utilizing the original braket :D. update Alternator is mounted. piece of cake. one thing, is there a need to change the 6v selenoid???
 

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