Model A Starter

You can't, really. Not without taking it apart, and even then it might not be obvious. The only difference is the field coils. Just use it. It's probably a 6 volt unit. It will be fine.
 
I would try it on the engine w/a well charged, good, 6 volt battery. If it turns over good it's probably a 6V unit, if it struggles to turn over then it's probably a 12 volt unit.
 
katy said:
I would try it on the engine w/a well charged, good, 6 volt battery. If it turns over good it's probably a 6V unit, if it struggles to turn over then it's probably a 12 volt unit.
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^^^^^^^^

True. That's what I would do.

I'll bet it is still setup for 6 volts.
 
I run a 6volt starter on my tourer but upgraded to a 12v system. the starter, unchanged at 6v, engages with a thud which is disconcerting. One person I consulted said remove 2 brushes from the starter. was this correct advise.
I might add the vehicle has broken two starter shafts and in time will possibly brake the current one too.
how do I address this??
with thanks in anticipation, gary
 
woofa.express said:
I run a 6volt starter on my tourer but upgraded to a 12v system. the starter, unchanged at 6v, engages with a thud which is disconcerting. One person I consulted said remove 2 brushes from the starter. was this correct advise.
I might add the vehicle has broken two starter shafts and in time will possibly brake the current one too.
how do I address this??
with thanks in anticipation, gary
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Gary-
Put 12 volt field coils in your starter and you're good.

When you hit the 6 volt starter with 12 volts, you are really winding it up, putting a load on the Bendix drive.
 
Remove the starter band. Look closely at the bottom (inside the starter)of the Electrical button post. If you see 2 field coil bus bars soldered to the post it is a 6 volt starter. One bus is 12volt. The reason is the 6 volt field coils are wound in parallel, thus the 2 bus bars. 12 volt starter fields are wound in series and have only one bus bar soldered to the button.
Many cars have had 6 volt starters with 12volt batteries running fine with no problems for years. In the last 2 years I have seen 3 or 4 cars with the starter ring gear pushed off the flywheel due to the heavy impact of the starter drive engaging the flywheel.
 
MAG said:
Remove the starter band. Look closely at the bottom (inside the starter)of the Electrical button post. If you see 2 field coil bus bars soldered to the post it is a 6 volt starter. One bus is 12volt. The reason is the 6 volt field coils are wound in parallel, thus the 2 bus bars. 12 volt starter fields are wound in series and have only one bus bar soldered to the button.
Many cars have had 6 volt starters with 12volt batteries running fine with no problems for years. In the last 2 years I have seen 3 or 4 cars with the starter ring gear pushed off the flywheel due to the heavy impact of the starter drive engaging the flywheel.
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MAG is correct. I convert my own starters to 12v by rearranging the field windings in this way. Tens of thousands of miles and no problems.
Another way of slowing down a standard starter is to use tiny battery leads. The thinner and longer the better to cause a voltage drop in them. That is exactly the opposite to what we do to get a 6v starter working well, I know but think about it! I've even seen bendix springs used as a resistor to do the same.
 
The 6v starter is two series parallel circuits. Two separate circuits that run in parallel with each other and in series with the battery. When converting to 12v you end up with one series circuit which increases the circuit resistance there by eliminating some of the initial shock. More voltage/less amperage. 12 on 6 causes a slam when engaging the starter; the Bendix is not designed for this sort of abuse. The initial torque/amperage draw is tremendous.
I have a starter armature somewhere that was run on 12v for many years; the spring stretched and wore a long helical groove in the shaft.
I talked a friend who was running 12v with 6v starter; I built a 12v starter for him and he is now a firm believer in 12 for 12.
To answer your question; if your starter and electrical system are in good shape and you install a 12v battery your engine should turn over as if the spark plugs have been removed. And 6v on a 12v starter would act like a dead or very low battery.
 
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A starter doesn’t care what voltage you give it. 12V runs faster than 6V. Only damage to a 6V on 12 is to the starter drive. Even that is often caused by a sharp tooth on the flywheel.
 
captndan said:
A starter doesn’t care what voltage you give it. 12V runs faster than 6V. Only damage to a 6V on 12 is to the starter drive. Even that is often caused by a sharp tooth on the flywheel.
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Tell that to the Model A owner holding a busted starter.
over voltage causes;
1) bent armature shafts
2) broken armature shafts
3) stretched/broken Bendix springs
4) busted/exploded Bendix
5) abused flywheel ring gear teeth
all this many times causing the starter Bendix to stick while engaged in the flywheel.
You are right though only because the starter is a short run intermittent use motor. If an engine didn't start for some reason and the operator turned the engine over for much more than 30 seconds; or the switch stuck as they sometimes do, the result would be a very hot starter.
There are too many negatives attached with 12 on 6. It may work but it isn't a good idea.
 
Add this as #6 to post 14.
In the last 2 years I have seen 3 or 4 cars with the starter ring gear pushed off the flywheel due to the heavy impact of the starter drive engaging the flywheel.

But, like so many other posted problems, this is not happen unless you have seen it or it happened to you. In my case, I caught it before it pushed the starter ring gear completely off the flywheel. Since then I have converted several starters to 12v.
 
MAG said:
Add this as #6 to post 14.
In the last 2 years I have seen 3 or 4 cars with the starter ring gear pushed off the flywheel due to the heavy impact of the starter drive engaging the flywheel.

But, like so many other posted problems, this is not happen unless you have seen it or it happened to you. In my case, I caught it before it pushed the starter ring gear completely off the flywheel. Since then I have converted several starters to 12v.
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I've seen that too. Tap the ring gear back in place and a few drops of Loctite 290 and all has been well for about 8 years now. EASY!
 
Right Synchro909 easy fix. That is how I fixed mine. No more trouble.
I have also fixed them the hard way.... after the ring gear has been pushed off,....i.e., pull the engine, remove the flywheel and replace the starter ring gear.
In all these cases but one there was no warning. A terrible noise with the ring gear rattling around in the flywheel housing.

One produced a loud knock with the engine running.
The ring gear was hitting the flywheel housing. Since it didn't come completely off it was a easy fix.
 
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