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One-Wire Alternator conversion - GM 10SI

20554 Views 10 Replies 5 Participants Last post by  ProMetalShop
OK, so I needed to convert my '48 tractor over to 12v and needed an alternator. The one-wire was the easiest way to go as it is really simple to wire up. The problem with most one-wire is they need to go to about 3,000 rpm to activate. So I got a self-exciting one wire kit from e-bay (about $22 shipped) and rebuilt the alternator.

Here's what I did.

First this is what comes in the kit. New bearings, too.

This is what they look like, I have a few lying around:

First thing was to remove the pulley/fan and the four bolts that hold the case halves together then pull off the front case. and remove the rotor assembly.

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Then I took a shot of the inside wiring for future reference. Note the placement of the insulated screws

Since I am totally rebuilding the alternator, I changed out both bearings as well. A 5/8" plug socket works great for pressing out (or hammering out) both bearings. It can be used to press in the new bearings too.

All sandblasted and ready for powder coating. It appears to be a 61amp?

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I pre-assembled the electronics - easier to install - and used the supplied pin to keep the contacts inside the housing until the rotor assembly is installed. I had to re-use the capacitor and the resistor from the old alternator. It's going on a tractor, so I guess the cap isn't a major issue. On a car with electronics I would probably replace that too.

I also took some emery cloth to the contacts:

All assembled and ready to button up.

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Another shot of the front;

Why it's a good reason to rebuild - the contacts are just about gone. This was the good looking alternator, so looks can be deceiving. It should last the life of the tractor.
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What year engine did you pull the alternator from? I wonder if I can make this work in my Falcon. Google time!
Most any '70s GM has this.

Here's a good site for info.
That was a great thread. I used to work in a Chevy Garage in my high school years and I used to rebuild alternators and or replace diodes etc. Haven't had one apart since 1970. Forgot how easy they are to work on. Thanks for the memory jog. MArk L
I read some stuff in the newer ford 3g alternators. They have a few more wires to hook up but are almost the same size as a older ford making it an easy swap. All i need to find is a ford 3.8 at the junkyard.
Great tech article Mike!
I bought a 10SI new at O'Reillys for $46 and converted it with the jumper from #2 to BATT. term. Mine seems to charge at 13.8 v. all the time and no revving to get it started.
That is a good price for a new alternator. I wonder what a JY would charge for the same part?
Excellent thread, have had issues with some Alts that had to excite to charge. Some seem to need less rpm's to start ?
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