[AT] Generator to alternator conversion, this time on the Super M

[BRUCE MAHR]

Good job! 
  
Bruce Mahr 
 
  
 
 
 

-----Original Message-----

From: Dean <dean at vinsonfarm.net>
To: 'Antique <at at lists.antique-tractor.com>
Date: Monday, 27 January 2025 6:05 PM CST
Subject: [AT] Generator to alternator conversion, this time on the Super M

 
 Several weeks ago I’d posted about swapping an alternator onto my JD 3020, a process which ended up with me having a spare 1-wire alternator on hand because I’d rushed into things on the 3020 without taking time to really study what that tractor needed.   So I’d figured “Okay, now that I’m an expert on alternator conversions and I have this brand new unused 1-wire alternator sitting here, I might as well swap it onto my Super M—which has never charged very reliably either.”   In hindsight my self-proclaimed “expert” designation might have been slightly optimistic.   But I did finally get the Super M swapped over, and it looks good and works well.   I replaced the original generator mounting brackets with Steiner's IHS829 bracket kit, which fit perfectly, and also used Steiner's ABC1426 1/2" belt pulley.   Took a couple of trial-and-error attempts to get the right size belt figured out, but I ended up with an A33. 
Seems like the default “clock position” of all the Delco-type alternators is the 3 o’clock position, which on an M-series tractor puts the little wiring plug a fraction of an inch away from the inside of the hood.  A 1-wire alternator doesn’t need anything plugged in there but it still seemed like asking for trouble to have it on the side, since the little rubber cap could get loose and just drop off, and I thought it’d be easy to change the clock position to rotate that plug up to the top.   (I’d done that on the 3020 and it was easy).   But I wasn’t paying close attention and ended up screwing it up, pulling things apart that shouldn’t have been messed with and which according to some YouTube videos would not be easy fixes.   So much for “I might as well swap this onto the Super M.”

So I changed course and went with a typical remanufactured Delco 10si 63-amp three-wire alternator just like the one I’d put on the 3020, which was inexpensive and on hand at a local auto parts store.   The three-wire of course *does* need the wiring plug on the side, so I had to change the clock position on the new alternator also, but it was easy and straightforward just like it had been when I did it for the 3020’s alternator.   60+ amps is a lot of power so I replaced the original ammeter with a 60-0-60 IH-labeled ammeter from Precision Tractor Parts and ran two parallel #10 wires instead of just one from the output terminal through the ammeter and to the battery cable post on the starter.  In hindsight the OEM ammeter and a single #10 wire would likely have been fine, since the actual current draw as indicated on the ammeter (even after cranking the engine over for a bit on a very cold day) looks like it peaks at about 20 amps and fairly quickly drops from there.   Because it's a three-wire rather than one-wire alternator I used Brillman's B3000-001 alternator wiring plug with a diode in the exciter terminal wire, which keeps output from the alternator from backfeeding the tractor’s ignition circuit and preventing you from shutting the engine off.   I used a heat-shrink butt-joint crimp connector to splice that exciter wire into the ignition wire coming to the coil, which was right there handy.  (Ignition wire + exciter wire on one side of the butt joint, and ignition wire by itself on the other side.)   The “GEN” warning light on the 3020 serves that same function of preventing the alternator’s exciter wire from backfeeding the ignition circuit once the engine is running, I think because so little current passes through the bulb filament, but the Super M doesn’t have any such light.   I thought about adding one in the switch box where the fuse holder is, but figured I'd already spent plenty of time and money fiddling around with this project.   Finished assembly fits under the hood with just a little bit to spare, and it's nice to see that ammeter needle move as it should.   Dean Vinson Saint Paris, Ohio          
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