MTFCA Forum

Hi everybody,

I've been working on converting a starter to run on 12v and have run into a problem. The field coils have been rewired and the starter has been assembled. When I hook power to it I can get the shaft to turn about a 1/16" and then it won't turn any further. My question is, do you have to change how the brushes are wired? The diagram I was using for the conversion shows them being wired the same way they were when stock.

Thanks in advance

The Model T Ford 6 volt starting motor field winding is wired series/parallel.
When you convert it to 12 volt operation you have to change the field to full series.
Ron Patterson

Look up this thread, it explains the process.

Here's the actual link to the thread that Bob pointed out:

viewtopic.php?f=2&t=10169

In order to maintain proper North.....South on each coil, wire siagram must followed.
I suspect that some of the coils have the wrong magnetism polarity.

Art Mirtes

These were the diagram that I followed when re-wiring the coils. Here's also a picture of the coils

Coils 1 and 4 must have the same polarity and coils 1 and 3 3 must have the same polarity but opposite that of coils 1 and 4.

To check this, with the armature removed from starter. Connect the starter to a battery, then touch each coil with a iron bar and see the polarity of each coil is with a compass.

Made a mistake. Coils 2 and 3 must have same polarity.
I entered a 1,instead of 2 in previous posting.

Art Mirtes

I tested the coils. Coils 1 and 2 have the same polarity and coils 3 and 4 have the same polarity. I'm unsure about how I would go about fixing this so that the coils have the right polarity.

It appears that while you had things out to modify, coils got rearranged. You'll have to undo that error.