6V to 12V conversion

[bighead]

Howdy. I have a question that isn't truck or tractor related, but I know that quite a few folks around here have lots of experience with older equipment, so I'd like to ask some opinions here.

My brother just bought a 1948 Studebaker Starlight Coupe (Champion). It seems to be in reasonably good mechanical condition, but the wiring is falling apart. It has the old cloth-insulated wire, and the insulation if just falling off all the wires. He is going to have to re-wire most of the car just to make it drivable, and is considering upgrading to a 12V system so that he can use a more reliable (and cheaper) modern alternator, and use modern 12V accessories (like a radio). The wiring and mounting of the alternator should be no problem, but my question is about the starter. Can a 6V starter be safely run on 12V? I've seen it done a few times old cars and tractors, but don't know how well it holds up. The ones I remember (a 1950 Chevy and an old international tractor) both spun the motor pretty fast and made more noise than you'd expect, but seemed to work ok.

Is this commonly done, to use an unmodified 6V starter with a converted 12V system? Or is he asking for trouble here? Is there any (relatively) cheap way of converting a 6V starter to work with 12V?

Thanks for any advice.
 

[JerryCPP(WA) (PIC)]

I have used a 6 volt starter on a 12 volt system several times. The starter turns twice as fast. It may eventually tear up the starter drive - I don't remember which type the Studebaker had in those years. My '55 Stude used a Bendix inertia drive, and it would work on either speed. As far as the rest of the car, change all the bulbs to 12-volt; they have the same bases and connections. The gauges will be a little different, I believe there is a 12 to 6 volt reducer available on line for gauges. If it is electric wipers they will go twice as fast, as will the heater motor. Have you considered a 6-volt alternator? You can get one wire or 3 wire 6 volt alternators. Keep the generator pulley you have, as it will go right on the alternator - very helpful if it uses the wide belt. Change the coil if you're going to 12-volt, and be sure you understand the 12-volt coil. Some use an external resistor and some have the resistor built in. The points and condenser will be the same. Either way you go, an alternator is the better choice. If you change to 12-v you can reduce the wire size too. Have fun!
 

[oldmopar]

Here are a few links that have some information

[url] http://www.ytmag.com/articles/artint131.htm [/url]

[url] http://www.oldengine.org/unfaq/six12.htm [/url]

[url] http://www.film.queensu.ca/CJ3B/Tech/SixVolt.html [/url]
 

[HalWA]

The easy way of doing a rewire job would be to buy a replacement wiring harness that was made for that specific car. I don't know if they are still available as new-old-stock (NOS) parts, but not too many years ago, there were LOTS of Studebaker parts available, and at very reasonable prices. I would suggest looking on the internet and in Hemmings to see what is available now. There also might be companies that can build a wiring harness for whatever you need, and they might be able to make it authentic enough so it would class as a real restoration. The other advantage is that such a harness should fit very easily.

Several companies offer "street rod wiring harnesses" that could probably be made to work in an old Stude. Or it is possible to build a new harness that approximates the one that is already there. The electrical system in most cars of that age was not all that complicated, and building a new harness, or at least replacing the parts of the old harness that are worn out certainly can be done. It takes a bunch of time, though. If I was going to rewire an old car, I would improve the wiring by adding lots more fuses than the original harness used. Fuses can prevent wiring fires if you get a dead short somewhere.

I often solder new terminals on wiring, since I think it makes a better joint than just clamping them on. The cheapie clamp on connectors have not always worked the best for me, but I know there are better connectors and clamping systems available.

If you want to convert to 12 volts and use a modern alternator, the 6 volt starter and solenoid should work fine, at least if it is in good shape. It even might start the engine much better with 12 volts than with 6 volts. You would need to use a ballast resistor on the coil with 12 volts, or you will be replacing the coil very soon.

I am not sure, but suspect that the old Stude used a positive ground system, and I think most, if not all alternators require a negative ground system. Hooking things up with positive ground will probably ruin an alternator almost immediately. If the car has a factory radio, the change in polarity might or might not be a problem.

Unless there is a problem with a change in polarity, a 6 volt radio, and the factory gauges can be made to work OK using a specially made, large resistor called a "volt-a-drop" that reduces the 12 volts to 6 volts. The heater and defroster fan motors can also be operated the same way, but I would suggest using a separate resistor. The resistors produce quite a bit of heat when current is running through them, so they need to be mounted where they get good airflow, preferably outside the passenger compartment.

One gauge that can be a problem is the ammeter. Most generators produced less than 30 amps at their maximum output, while most modern alternators produce more than twice that. The ammeter might work fine operating on 12 volts if the alternator is not putting out much juice, but if the battery is ever low, it is very possible to SMOKE an ammeter and even cause a fire if the alternator is really producing electricity. I would not try to run all the power through the ammeter as they originally did with the generator if I switched to an alternator. Maybe just the power to the gauges, lights and radio.

It is not hard to change all the bulbs to 12 volt models that fit the sockets, but it takes some time. When you take out the old bulbs, it is a good idea to shine up the electrical connections in the old sockets, and make sure the grounds are good. The turn signal flasher unit will need to be replaced with one that is for 12 volts.

Converting to 12 volts and using an alternator is a major decision in building an old vehicle. Since the car was built with the 6 volt system it has, the various parts fit right and usually work right together. To be "restored", most people would say that a vehicle has to be set up just like the manufacturer built it, and that would mean leaving it as a 6 volt system. Converting to 12 volts has some advantages, but you have to come up with a mounting/adjusting system for the new alternator, which can be challenging. It is absolutely necessary to mount the alternator just right, with the right pulley for the existing fan belt, and as solidly braced as the alternator was supposed to be braced stock, or the vehicle might not be as reliable as you would want. It is VERY ANNOYING to constantly be throwing belts...BTDT!

Unless the whole wiring harness is really bad, I think I would try to patch the bad spots, at least to get the vehicle going. Once I got it operational, I would think about a new harness, if necessary, and about maybe the 12 volt modifications. Good luck, HTH!