12 volts conversion

[carlos1940]

how to convert from 6 volts positive ground to 12 volts negative ground.

[brokenspoke]

The search function is your friend

[woofa.express]

Yes Carlos1940. There is plenty of info in this forum on this subject.

Even though my 6V system was okay, I modified it to 12V mainly because the higher cost of replacing the battery with another 6V compared to a 12V.
After the upgrade I became nervous and uncomfortable about the severe impact of the dog into the ring gear so I also changed the starter motor to a 12V.

Not everything went smoothly and I wish I had gone for the modern starter which engages smoothly. I also included a solenoid and key which is part of the modern starter motor anyway because that appealed to me.

[nkaminar]

As Woofa said, the starter is the big deal. You can buy the 12 volt field windings and modify the starter yourself but you need a good large soldering iron. The other end is the generator which will put out 12 volts but needs to be re polarized to negative ground, or an alternator replacement. The alternator is the better choice.

The horn can be rewired or a resistor placed in series. Same for the electric windshield wiper. The rest is just replacing bulbs.

With 12 volts the GPS and cell phone charger will work. I also run a car camera pointing out the rear in case someone rear ends me. A car came close yesterday when it cut across 2 lanes in back of me to make a turn. Some drivers are reckless.

[CT Jack]

I cannot understand why many Barners go through the cost and agony of converting from 6v to 12v. I have found that if you have a good 6v battery, good operating 6v generator, a good 6v starter motor, properly tuned engine (points, plugs, timing) and proper wiring, the original 6v system works perfect. Recent availability of LED replacement lights reduces the power load demand from the generator. Many of these lights are no longer polarity sensitive even the more recent LED head lamps. Dimming at idle with a 6v generator is no longer an issue.
If you need 12v for your usb and gps devices buy a small dry cell 12v rechargeable battery to power these devices. When you get home use a battery charger to recharge it. Keeping the Model A 6v system will save a time and $$.

[Badpuppy]

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For 12V generator you need to replace the field windings, otherwise the 3rd brush won't adjust properly. Then repolarize as nk said. Cutout - diode type or 12V relay. I agree alternator is better choice.

Swap posts on battery, ammeter and ignition coil. (Use original ammeter.)

[Badpuppy]

Originally Posted by CT Jack

I cannot understand why many Barners go through the cost and agony of converting from 6v to 12v.

You have a point, Jack.

[BillLee/Chandler, TX]

https://cedarcreekas.org/TechTopics/...rn_Signals.pdf

[daren007]

Why reinvent the wheel. The 6volt system works just fine.

[Bob Bidonde]

There is no need to modify the Model A's starter motor for 12V operation. I have been running original starter motors with 12v for over 30 years with success. Use the Bendix drive that has 3/8" diameter bolts or better yet, convert to a modern starter drive. I have not seen any damage or unusual wear on the ring gears in my cars.

[MAG]

Some folks are lucky that the starter drive does not push the starter ring gear off the flywheel on 12volt systems with a 6 volt starter. Had 4 or 5 come into my shop with that very thing happening. One of them was mine. It does not damage the ring gear. Just pushes it off. You may not know it is happening until you hear a awful knocking sound if the engine starts before the ring gear comes off. The reason it comes off is the starter bendix engages from the back side of the ring gear, opposite from the direction the ring gear is installed.
Safe thing is to convert the starter motor to 12 volts or buy one.

[Synchro909]

Originally Posted by Bob Bidonde

There is no need to modify the Model A's starter motor for 12V operation. I have been running original starter motors with 12v for over 30 years with success. Use the Bendix drive that has 3/8" diameter bolts or better yet, convert to a modern starter drive. I have not seen any damage or unusual wear on the ring gears in my cars.

Just like the 1/2" shaft wasn't strong enough for even a 6 v system, a 5/8" shaft isn't up to a 12 v one. When my Brother in Law bought a Model A recently, it had been converted to 12v some time before. I didn't like the way the pinion crashed into the ring gear so I offered to convert it to 12v for him. When I checked the armature shaft, I found it had a decent bend in it. I put it down to an unmodified starter being used on 12 v.
A 6v starter will take 12v but not for very long. I ask myself "Why wouldn't I convert it to 12v and eliminate any chance of trouble down the road?" It cost me nothing but a little time and a dollar's worth of materials.

[Herb Concord Ca]

As I have said in the past you need 12 volts when you add A/C to your Model A. You should also convert your starter for the reasons mentioned above.