I was thinking of changing to 12 volt negative ground.

[1928 Sport Coupe]

I have been thinking of changing from 6 volt positive ground to 12 volt neg ground. Before I try to get the 1930 running I need to change all of the wiring. Which way should I go if I decide on 12 volts?
1 Should I buy or rebuild the starter as 6 volt and use the modern type drive? Would this last with 12 volts? I hear the original drives will not hold up to 12 volts.
2 Should I buy or rebuild the starter with 12 volt fields and the modern type drive? I also see Snyders has a rebuilt starter available that has a stud mount for the power cable, but that would require a solenoid and a push button. Has anyone used this starter?
3 Should I go with the new gear reduction starter? I'm not sure if I like the looks of the new gear reduction starter. Has this one proven to be reliable?
There is not a lot of difference between the price on the above choices depending on if I buy a rebuilt starter or rebuild it myself.
I was also looking at the 12 volt alternator kits. Has anyone used a 1960's 35 amp Ford alternator instead of the Delco alt? It would be hard for me to put a GM Delco part on my Ford. I think I have a NOS Ford, Autolite or Motorcraft 35 amp alternator and wiring connection. Would the Ford alternator fit the premade brackets the Model A suppliers have? Has anyone else used a Ford alternator?
Some time the car has had the points replaced with the Modern V8 points and condenser and the NU-REX distributor plate.
I would like to keep it looking original as much as I can. I think the 12 volt would be less cost overall and be more reliable.

Thanks for any assistance.

[Tom Endy]

Converting to 12-volts is a personal choice. There are several good arguments for doing so. One is you can buy a 12-volt battery and a 12-volt alternator at most any auto parts store and you will have the ability to run a GPS and charge your cell phone.

You do not have to change the wiring to make the change. The six-volt rated wiring is an overkill for 12-volts. The reason the auto industry went to 12 volts in 1955 was to be able to reduce the cross sectional area of copper wire and save millions of dollars each year.

You should re-wire the ahooguh horn for 12-volts and not use a dropping resister as they will burn out. The attached article tells you how to do it.

http://www.santaanitaas.org/wp-conte...orn-to-12v.pdf

Tom Endy

[1928 Sport Coupe]

Tom:
I was going to change the wiring because it is in terrible shape. The previous owner left it in a barn and the mice destroyed the interior and the wiring. At least they stayed out of the engine, radiator and driveline, as far as I can tell so far.
I am about to rebuild a horn for the car now. I will not be able to bring the car to my garage until spring. So I am trying to do small items like the horn & maybe the starter, and etc. for now.
Thanks

[nkaminar]

If you have the electric windshield wiper you will have to address that too. In my car I used a variable voltage regulator to supply the wiper motor. So now I have a variable speed wiper motor.

Another advantage of 12 volts is the LED rear tail light assembly that screws in place of the normal lens. Very visible especially when used for turn indicators.

[Bob Bidonde]

Use a 12V ignition coil with an internal resistor. Go with a negative ground to be compatible with modern electronics. Here is some guidance:

[jwmckenzie]

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Originally Posted by 1928 Sport Coupe

Tom:
I was going to change the wiring because it is in terrible shape.
Thanks

I suggest you use original type (6V) wiring, regardless of 12V or 6V. That way if someone wants to go back to 6V the wiring will accommodate it. An additional benefit is that it will look original as well.

[Kurt in NJ]

I have kept mine stock except for diode cutout, the original generator has be more reliable than the alternator in the 74 Chevy truck.
The Chevy alternator has been rebuilt 3 times in 40 years, the original generator I just replaced a bearing after 50 years, and I run the generator at amps that many would cringe at —14 amps, down from the 18 amps I used with 50 cp regular bulbs, now I am using halogen bulbs.
Some of the usb chargers don’t seem to care if they only get 6V instead of 12
I have used voltage/ polarity converter on other positive ground cars..
When a alternator is used it will need a smaller pulley to spin it fast enough, that will mean you need tighter belt tension, that creates a need for improved bearings in the water pump, the one wire alternator draws a little electric when sitting, now you need battery disconnects to keep it from going dead when sitting.
With the Optima battery my cranking speed is fast enough that people say I must be hiding a 12V battery somewhere, haven’t touched the starter in 50 years, but I have abused it, have about 100 feet driving under starter power, and when the clutch was stuck I used the starter in gear to get going at stops.
The need for modifications are pretty much eliminated by proper restoration to original specifications..

[FordAADump]

There's really no good reason, in my opinion, to change to 12v. 6 volt works just fine and obviously the cars were built that way. The only thing I would do is update the generator to an alternator, which you were mentioning. There's a company call Power House (I believe) that makes one that looks nearly identical to the original and will give you all the amps you need for night driving etc. Good luck and safe driving

[1928 Sport Coupe]

Tom Endy:
Thanks for the link to the horn rewinding instructions. I have the wire on order.
nkaminar:
The wiper motor that came with the car is a vacuum motor. It was in a box of parts. I am not sure it is correct but it works and I plan to use it if it will fit. I very seldom get my cars out in bad weather, except for the daily drivers. I intend to install LED lights all the way around. My 28 Sport Coupe has LED's.
Bob Bidonde:
I love your charts and diagrams'. I should have some coils on hand. I still wonder about the modern starter drives, I have seen both good and bad about them.
jwmckenzie:
Yes I plan on using the reproduction wire harnesses available. I do plan on making my own turn light harness just like on my 28. I used the bulk wiring and bulk loom from Snyders so it fit in with the other wiring.
Kurt in NJ:
6 volt batteries are hard to find here unless you are willing to take one that has set on the shelf for up to a year or drive to the bigger city's. Some stores do not have them other than special order. I waited 3 days to get a fresh 6 volt Optima in my 28, even than it was 4 months old. I just have an aversion to using a GM alternator in a Ford. I need to compare the dimensions of the Ford alternator and the GM alternator.
FordAADump:
I am still thinking as to 6 volt pos or 12 volt neg. If I can use the Ford alternator I probably will change it. The GM alternator probably will be enough for me to keep it 6 volt. But I am definitely leaning 12 volt. The Power House alt does not interest me. To expensive and parts availability. I want to be able to get parts locally if needed. I also want to be able to put it back to 6 volt pos ground with minimal effort.
My main concern is the starter. I would like to have more information on what starter to chose for 12 volt.
Thanks for all the information

[Kurt in NJ]

I have done the 12volt conversion with a sawsall, i cut the xtra 6v off the 12 v battery

[jack backer]

I set up a modern electrical system using relay controlled and fuse protected circuits, LED lighting, a 12v horn, delco 10si alternator , FSI distributor and used a 6v starter with a modern Bendix.

In my opinion the stock electrical system is quaint, and can be used. I modernized due to the advancements made in automotive electrical systems ove the years.

6v starter will live on 12v, it ‘hits’ harder so I used the modern cushioned Bendix to offset it.modern distributor and Hall effect ignition provides precise timing at all rpm ranges..the delco looks out of place but performs flawlessly, all components last longer with consistent voltage.

[BillLee/Chandler, TX]

Originally Posted by Tom Endy

Converting to 12-volts is a personal choice. There are several good arguments for doing so. One is you can buy a 12-volt battery and a 12-volt alternator at most any auto parts store and you will have the ability to run a GPS and charge your cell phone.

You do not have to change the wiring to make the change. The six-volt rated wiring is an overkill for 12-volts. The reason the auto industry went to 12 volts in 1955 was to be able to reduce the cross sectional area of copper wire and save millions of dollars each year.

You should re-wire the ahooguh horn for 12-volts and not use a dropping resister as they will burn out. The attached article tells you how to do it.

http://www.santaanitaas.org/wp-conte...orn-to-12v.pdf

Tom Endy

Tom's article on rewiring the horn is excellent, as are all of his writings! I'd add that using the 12v dropping resistor is a quick and dirty fix that can be used temporarily until the horn is rewound.

As I have one in my car, I can attest that they get hot when the horn is used. I can also say that the horn is never used for more than a quick tap every now and then, and the resistor has worked for the 15 years I have had it installed.

My 'round tuit' list is long! :-)

Regards,

Bill Lee

[Synchro909]

I will NEVER have another one of those modern style Bendix drives. They don't engage the ring gear fully which leads to premature wear on it and a bent shaft. Don't ask how I know that! They were not designed for the Model A.
I have thrown the ones I had as far as I could and bought original style replacements.

[cas3]

I have an alternator on one of my A's only because it gets driven at night a lot. Its 6volt positive ground, I love it. Now, horn, electric w/s wiper and lights all work at once !

[nkaminar]

OK, here is a lithium battery that is designed for motorcycles but can be used to start a Model A. 900 amps cranking capacity. Smaller than the normal battery and lighter. Uses different terminals that I know nothing about.

https://antigravitybatteries.com/pro...-oem/atx20-hd/

[Dick Carne]

As mentioned, there are both pro's and con's for converting to a 12-volt system or staying with a six-volt system. I personally converted each of ours to 12-volt systems. When I initially made the change on our roadster, it was because even with an alternator, the lights would quite often dim whenever I would make a stop. The 12-volt conversion seemed to cure that issue. However, that was done before the days of LED bulbs (which I understand do not draw as much current as conventional bulbs). One of the draw-backs that I have experienced, is that on our Town Sedan, the starter seemed to "slam" into the flywheel gear, and over the course of about 8500 miles (since the engine rebuild), eventually sheered off some of the flywheel gears. As a result, I had to replace the flywheel gear, and I've since put new 12-volt filed coils in the starter, and that seemed to take care of that issue. On our touring car, the horn sounded more like a loud "splat" rather than the more typical "ahoogah". I'm currently having it rewound so I am hopeful that this modification may cure that issue. However, our roadster horn sounds like it is supposed despite using a 12-voilt system. As Tom Endy mentioned, the 12-volt system will support GPS and cell phone chargers (we also installed heated seats in our Cabriolet using the 12-volt system - not sure if this could have been done easily if we still had a 6-volt system). And finally, as Bob Bidonde referenced above, if you should decide to convert to a 12-volt system, be sure to use a 12-volt coil with an internal resister - those without an internal resister will work for a short time, but will in all probability not last for more than a year or two at most. I hope that these insights will prove helpful to you. Good luck to you whichever way you decide to go.

[Synchro909]

I have considered a lithium battery for modern and vintage cars I have but I haven't gone further than that. I'm concerned about the number of them that catch fire and I don't know it they can be properly charged by an alternator.

[nkaminar]

One option for those of you who do not want to convert a 6 volt starter over to 12 volts, is to use a Bendix spring as a resistor. It is placed in series with the starter. Easiest place is at the terminal on the starter switch. The resistance is not enough to disturb the normal running and charging of the car but it can reduce the voltage at the starter when cranking. It may effect the ignition when starting unless you wire the car from the battery side of the Bendix "resistor." This fix is used a lot on Model T's. It reduces the slamming of the starter Bendix. I think the Bendix spring for a Model T is smaller and may be a better choice for the Model A starting resistor.

[Bill G]

One thing to consider about wiring conversions, whether just going 6v to 12 volt or other interesting additions. I have seen here and on Facebook a number of posts by people who bought or inherited a Model A and had acquired a big mystery of electrical issues. Usually, where there are a number of changes, not only is the acquirer of the car puzzled, but any help from anyone who tries to guide them along normal troubleshooting steps will usually result in frustration or downright stymie. Often delaying for the new person some well deserved enjoyment of their new find. Even a person who rewires or makes creative changes on their own car may forget what they did a few years later. (Don't ask me how I know).

If you do make changes, no matter how subtle, make a detailed revised wiring diagram! Just saying!

[Pete]

There are several options for the starter when going to 12 volts.
1- Do nothing and just use it as is. It will last for quite awhile.

2 - Change to 12 volt field coils in the starter.

3 - Change the field coils and change the bendix to the tractor
style.

4 - Change to a gear drive type starter. You will NEVER have to
buy or have any starter trouble again.