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11-27-2023, 04:37 AM | #1 |
Junior Member
Join Date: Sep 2023
Location: German/French border
Posts: 27
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12 conversion
Pro's and con's of a 12v negative ground conversion of my 6v positive ground 1930 Tudor? Do I need to do more than change the alternator, coil, lights and relays, and ammeter, and use a voltage converter for the horn? I have already switched the starter motor located fuse to a circuit breaker on the firewall and added fuses to all of the light systems.
Why do I want to do this? I get rather nervous when that 6v battery sounds like it barely turns the engine over. It has always started but it always sounds like it will not. If a $1000 worth of parts will end that I am up for a few hours of work to make it happen. Also...with the battery in the stock location it is a pain having to lift the carpet and floor board panel to use a battery trainer and keep the battery fully charged when not being driven often. Perhaps an alternative location such as the running board? I have a red top battery...which has a thinner profile than normal but it will not fit behind the rear seat (I have a three door Tudor). Advice please? |
11-27-2023, 06:56 AM | #2 |
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Join Date: Jan 2019
Location: Germany, near Aachen
Posts: 1,163
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Re: 12 conversion
Hello, [your first name could be written here],
The tired turning of the starter motor has nothing to do with the fact that it only gets 6 volts. You already have a start relay; check whether the collector is clean in the insulator joints and has a smooth surface and the brush carbons slide smoothly. You have to have at least a finger-thick cable from the battery to ground and to the start relay and the starter motor. Tired starting speed is not a problem, as long as the mixture and spark are correct, the low compression engine comes on at the first revolution. I connected an on-board charging socket to the battery and screwed it into the heel side of the footwell. That's plug & load. Gruesse vom Aachener Land!
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Beste Gruesse aus Deutschland, Werner Ford Model A, Roadster, 1928 Citroen 11 CV, 1947 Hercules W 2000, 1976; (with NSU-Wankel Rotary Engine), Canadian version |
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11-27-2023, 07:14 AM | #3 |
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Join Date: Jul 2012
Location: Central Maine
Posts: 647
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Re: 12 conversion
I agree with Werner. 6 v Model A Ford's are legendary. Do you have the correct cables ? Are connections clean with no paint ? Starter switch the same ? Are all cells up to a good level ?
I do not deal with the battery in my '29 during the season except hal; way thru when I check the fluid. Bill |
11-30-2023, 04:56 AM | #4 |
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Join Date: Sep 2023
Location: German/French border
Posts: 27
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Re: 12 conversion
Thanks so much for the idea of a plug in charger outlet. I did not know that such a thing exists.
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11-30-2023, 05:28 AM | #5 |
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Join Date: Sep 2023
Location: German/French border
Posts: 27
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Re: 12 conversion
Werner, Excellent suggestions.
Grüße aus der südlichen Weinstraße |
11-30-2023, 05:57 AM | #6 |
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Join Date: May 2010
Location: VA
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Re: 12 conversion
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11-27-2023, 08:16 AM | #7 |
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Join Date: Mar 2011
Location: Mebane, NC
Posts: 192
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Re: 12 conversion
My 30 is 12 volt and I love it .
It is said that a properly maintained 6 volt system with the correct cables will offer excellent service and I believe that . For me I just prefer 12 volts . As for battery location I believe the stock location is fine . I have a battery maintainer on mine and the harness is hard wired onto the battery clamps with the plug hanging under the floor where I can quickly access it to plug and unplug. Look at the Noco Genius 1 or 2 for a good maintainer , availible on Amazon for us in the USA . They come with the pig tail wiring that you can hard wire to the battery. That charger is 6 and 12 volt Last edited by petew; 11-27-2023 at 08:22 AM. |
11-27-2023, 08:52 AM | #8 |
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Join Date: May 2010
Location: Long Island, NY
Posts: 3,519
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Re: 12 conversion
Speaking from experience, the starter motor does not need any rework to run reliably on 12V. Also the ring gear can handle the higher torque of the starter motor without any excessive wear or breaking loose of the flywheel. The stock Bendix drive however will not survive, so replace it with a modern starter drive that is made in the USA.
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11-27-2023, 09:50 AM | #9 |
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Location: Western North Carolina
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Re: 12 conversion
The horn can be rewired for 12 volts fairly easily. Instructions are here on the barn somewhere.
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A is for apple, green as the sky. Step on the gas, for tomorrow I die. Forget the brakes, they really don't work. The clutch always sticks, and starts with a jerk. My car grows red hair, and flies through the air. Driving's a blast, a blast from the past. |
11-27-2023, 11:08 AM | #10 |
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Join Date: May 2010
Location: Southern California
Posts: 3,138
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Re: 12 conversion
The Model A works just fine on 6-bolts. However, there are some good arguments for changing to 12-volts. Twelve-volt batteries are not readily available at most auto parts stores. There may come a day when they are no longer available. Modern gadgets need 12-volts for recharging, cell phones and the like.
During the conversion it is best to re-wire the ahooguh horn as the dropping resisters will burn out with repeated use. The attached article is how to do it. http://www.santaanitaas.org/wp-conte...orn-to-12v.pdf Tom Endy |
11-27-2023, 11:13 AM | #11 | |
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Join Date: Jul 2011
Location: Redondo Beach, CA
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Re: 12 conversion
Quote:
I have had good luck getting 6 volt batteries at the local O'Reilly's. But like Tom suggests, "There may come a day when they are no longer available." Last edited by Y-Blockhead; 11-27-2023 at 11:26 AM. |
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11-27-2023, 11:15 AM | #12 |
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Join Date: May 2010
Location: Pine, AZ
Posts: 797
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Re: 12 conversion
Send me an email [email protected] as have a lot of information about bulbs, electrical etc.. I have a 12V negative ground system using the original generator and replaced the 6V battery with a 12V battery. The battery is the load that sets the voltage. You can use a dropping resistor for the horn. I also installed a relay for the horn. Have the Bendix mentioned above on the starter. Have converted the tail lights to LED as they are brighter. Use the 50/32 candle power headlights. There are LED headlights, but do very little driving at night so have not converted.
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11-27-2023, 02:30 PM | #13 |
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Join Date: Mar 2012
Location: Ohio
Posts: 2,033
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Re: 12 conversion
Hmmmm. You guys make it sound as if changeover is not all that big of a deal after all. Just follow the process.
So what is the benefit of 12V in the real world? Can change starter bendix and reuse starter, can rewire horn and resuse, can reuse generator....hmmm. Last edited by Gene F; 11-27-2023 at 02:41 PM. |
11-27-2023, 04:28 PM | #14 |
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Join Date: Feb 2019
Location: Erie Pa
Posts: 708
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Re: 12 conversion
Hello, 6 volt systems work good with proper large size battery cables. I have seen it done a couple of times, people change the battery cables by going to auto parts store and buy “battery cables “ that are for 12 volt systems and are of a much smaller diameter (gauge) than 6 volt and the problems begin.Large cables and good grounds are important. I can understand though if you are running cell phones , cb radios , etc . Converting to 12 volt.
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11-27-2023, 05:01 PM | #15 |
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Location: San Antonio, Texas
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Re: 12 conversion
No offense to anyone but I like my antiques to be, well, antique. I love the sound of a good 6-volt starter. I also love the simplicity of the old timey stuff. 12-volts is OK for a model T but they have a magneto and the coils like higher voltage when operating on battery.
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11-27-2023, 05:12 PM | #16 |
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Location: VA
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Re: 12 conversion
Make sure your battery ground and starter cables are 50 or 55 mm2 size per https://www.lapptannehill.com/resour...nversion-chart
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11-27-2023, 05:21 PM | #17 |
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Join Date: Mar 2012
Location: Ohio
Posts: 2,033
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Re: 12 conversion
When I was younger I always tried to buy the 6V cables for my 12V daily drivers because they were heavier. Now days it's all about cheaper, cheaper, cheaper.
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11-27-2023, 05:38 PM | #18 |
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Join Date: Jun 2014
Location: Melbourne, Australia
Posts: 7,564
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Re: 12 conversion
I have converted all of my four Model As to 12 volts and I've learned a lot in the process and in the 20 years or more since I did the first one. Here are a couple of things about going to 12 volts.
1. The starter will eventually give up unless it is converted to operate on 12 volts. A bent shaft is common a certainty in the long run. Once the conversion is done, the original style Bendix is fine. 2, The is no need for a dropping resistor for the horn. It is a simple task similar to converting the starter motor to convert it to 12 volts 3. There is no need to change the ammeter - it will operate just as well on 12 volts as it did on 6. 4. Your 6 volt coil will be fine if you connect a ballast resistor in series with it. You may be able to get one from an old car or from an electronics supply shop. You will need a resistor of about 1.5 ohms with a minimum of power rating of 40 watts, preferably 50. Instructions on how to do the conversion to the horn are here somewhere on the forum. If I can find them in my "library" of Model A stuff, I could send you a scanned copy if you like and I could give a detailed explanation of the starter conversion. I have not seen instructions on how to do the starter anywhere but I worked it out from a set of vendor supplied field coils (which failed). I have done several starters for other people and none have failed as far as I know. Send me a PM if I can help.
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11-27-2023, 07:01 PM | #19 |
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Join Date: Jun 2010
Location: College Station, Tx
Posts: 326
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Re: 12 conversion
I have a 12V in my touring mode A because 6V can be hard to find sometimes, my other model As are 6V. The other As have a cut out in the floor board large enough to lift the batter out without removing the floor board. I put the battery maintainer on the starter and the other on a head bolt never had a problem and i have had Model As almost 40 years.
A |
11-28-2023, 12:22 AM | #20 |
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Location: Concord CA
Posts: 652
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Re: 12 conversion
All the above about 6 volts is true. A Model A will run just fine on 6 volts just fine. The only reason to change to 12 volts is if you add Air Conditioning to your Model A! Our touring car, 31 Slant Town Sedan has been Air Conditioning since 2010. Converted both the horn and starter to 12 Volts.
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