Converting a WD to 12 volt

The generator requires flashing when changing the battery polarity and should be flashed after its been to the shop for testing or repair. Flashing puts the proper polarity magnetism in the field poles so it generates the proper polarity. Flashing involves jumping the B to A posts on the voltage regulator before starting the engine. There is often a spark when breaking that jumper after a couple seconds, hence the name flashing. A generator that builds voltage opposite polarity of the battery can have a short life, and the voltage regulator/cutout will have an even shorter life.

The coil primary polarity should match the battery polarity for the best spark. E.g. + on the coil to ignition switch for negative ground, + on the coil to the points for positive ground.

The connections on the ammeter need to be swapped when swapping polarity so it indicates properly. For negative ground the - post needs to go to the battery positive post and the + post to the generator regulator and all the electrical loads through their switches. For positive ground the + post goes to the battery and the - post to the generator and loads.

Radios are sensitive to polarity and modern solid state radios can fry instantly with reversed polarity. Not much in solid state radios for 6 volt systems.

Gerald J.

That's an interesting point. I never fully understood the difference between positive and negative ground.  And what it takes to switch from one to the other.

Well, got back to the WD starting problem today. Took the starter to a co-worker who rebuilds them regularly. He said it looked real good inside as far as the brushes and shaft bushings go, but the big spring inside just didn't look normal. He put a new drive on it and put it back together.

One of my WC's is still a 6 volt and also has a magneto on it.  It has a battery, but I never use it.  I don't even know if it has a charge?
I have it set up so that you can take and lightly pull o the crank and it pops right off.  Your son could do it, it's that easy.  It all has to do with carb setup and timing and magneto.  If you'd redo your mag so that you get max spark, it really makes a difference.
My CA is 6 volt and I'm torn between changing it to 12v and leaving it 6.  All I use it for is cutting grass, but if I ever need it at night,,,,,,well, I'd change it over then.
I changed my C from 6 to 12 and was glad cause I used it at night a lot and the brighter lights paid off.  Seeing as you use yours at night a lot, you probably will want to also.  The LED bulbs make ONE HECK OF A DIFFERENCE...
But yeah, CLEAN BIG cables are best.  Your ground is fine, it's the one going to the starter that needs to be a MINIMUM of 2 and I agree with using 00 if you can find it.  Welding cables are the BEST though.  And you know where to lay your hands on some of that..hehehe

Marv,

If originality is very important, stick with 6v, replace the cables, clean all the connection points.  If you want faster cranking, lower battery maintenance, a greater choice of batteries, the ability to jump-start other machines (and have them jump-start you), would like to add great lighting or other electronics, swap the battery to 12v negative ground, put on an alternator, and replace the bulbs in all the lamps.  I've converted all mine, and a dozen of others', for those reasons... with absolutely no complaints of any kind.

One thing that nobody has noted-  the worst thing you can do to a starter motor, cables, solenoid, and battery, is underpower it.  When you stall or drag a starter motor, the windings carry substantially more current, and the stall and drag is irrelevant of reason- poor bearings, worn brushes, or insufficient current and voltage supply from the system.   When you provide ample voltage and current to spin the starter motor, it's draw is lower, because the higher armature speed means faster commutation, and the reactance in commutation is substantially higher.

The starter in my Hercules 338ci JXLD inline six is a 24v DELCO starter.  I'm cranking it with a 12v 4D truck battery, and it rolls it over just as well at 12v as it does it's original 24v... it just draws three times as much current.  When I took it to my local shop for a rebuild, I asked them what it'd take to swap the windings for 12v operation, he looked it up, and said same starter uses all same componentry, and same wiring... no difference between 12v and 24v for that unit... just a different solenoid winding, and a different reading on the meter under load testing.

Now, I took a listen to your WD start, and what's happening, is that when your engine crosses TDC and SLIGHTLY fires, the starter is unable to 'stay with' the ring gear as it speeds up.  By the sound of your starter bendix, I'd say you'd benefit from a starter rebuild.  The kicking out is not only annoying, it's hard on the ring gear and starter bendix.

The ground strap is a bit long, but that's probably not having as much impact as the ground connection path from the cover bolt to the starter housing.  On these, the starter nose is simply slid into the torque tube casting, and a binding bolt clamps down on the starter nose shell.  When you rebuild the starter, cleaning the casting, nose, and that bolt point and threads WILL help.  I don't understand why AC didn't spec a grounding lug on the side of the starter shell, but they didn't.

Your magneto impulser sounds really sharp and loud... perhaps it's just your camera and the inside of he building, but all my magnetos aren't that bright and metallic-sounding...  almost sounds like the impulser's internals are hammering against the housing a bit.

If you really, really, really want a good-starting tractor, hand-crank it... and then get the carbeuration an magneto set up so that it'll hand start easy.  After that, it doesn't matter WHAT condition the battery, cables, and starter are in, it'll still start easy...


Edited by DaveKamp - 05 Mar 2018 at 9:50am

Basically it boils down to with a 6V system you hope it'll start,with 12V you make it start.
12V is a lot easier on the starter because the engine will almost instantly fire up
once you hit the starter.Also 6V batteries don't hold up well compared to12V I've used.
We struggled with our WD45 for years with a 6V system then finally changed over to
12V should have done it years before we did.Was very nice to go out on a 10 degree morning and hear the motor spin over and fire right up.
When it comes to a tractor I'm using to work with I want what works best not some antique system that was state of the art 50 years ago.You still use the same phone(if you even had one) that you used 50 years ago?

Actually turned over quicker than I expected. Much faster than dads CA even with a new battery. His starter stops after a revolution or so of the engine. Two quick pulls of the starter rod and then it usually starts. May need to look into larger battery cables and a starter rebuild also. I dont want to convert his to 12v if I can resolve the issue.
Good post

Found some other posts, looks like 00 gauge is the way to go.

 

When I go up to dads, I'm always in a hurry. Gotta run up there, usually with at least one kid, try and get something done, then scramble back to town for the next sports or family or school event.  And heaven knows, if you are in a hurry, nothing goes right so everything takes longer anyways.  The WD has always been the workhorse.  I've always just jumped on it, did what I could, and left.

Anyways, here's the starter and cables.

 

 

 

 

 

And here is a video of how it starts....eventually.

 

https://www.youtube.com/watch?v=LEs77eFsmPk

 

Keep in mind, it usually starts a little better than this, I just crank it and pull the choke rod out, as soon as it pops once, shove the choke back in and off it goes.  But I didn't have enough hands while filming.

 

So, since it will be mud season before you know it, and warming up a bit, might be the perfect time to rebuild the starter, new cables, plugs and wires, and valve adjustment, before we start field work in the food plot.

 

What is the recommended size battery cable for 6 volt?

Edited by littlemarv - 04 Mar 2018 at 8:57pm

Kind of glad I started this thread. You guys are reminding me of everything I'm neglecting! Come to think of it, I have never put plugs and wires on it, or set the valves. I guess it's time to perform all the maintenance I have been "too busy" to get done. It starts better in the summer, but now that I have been using it in the winter, problems have been creeping up.

Stick with a 3 wire alternator, it's not that hard to do and the exciter circuit will lower the RPM to get it charging. On my WD I put a charging light on the dash to serve as the exciter amp draw, once I rev the engine a little bit the light goes out and the volt meter jumps up to around 14v and stays there even if I throttle back, charges good.

When it was absolutely necessary to jump a 6 volt tractor with a 12 volt, I have jumped directly to the starter....a bit of fire when you make the connection but it bypasses all the 6 volt stuff. With battery ignition, your 6 volt battery has to have enuf life to provide fire to the points.

We offer a complete 12V conversion kit for the WD/WD45 if interested. Visit our website. There's plenty of info on conversions, what to do, what not to do etc. Plenty of pics also to look at. Pics of the wiring systems also.  Be glad to help ya out anytime.  Forgot to mention, if your Starter is about done, I can change it over to 12V's the correct way. Its always better to change the Starter to 12 if your going to convert the system to 12. Appling 12V's to a 6V Starter motor makes the Starter violent. This could lead to broken nose cones, damaged ring gears etc.  HTH

Edited by Steve in NJ - 04 Mar 2018 at 10:59am

The only thing I understand about the starter using 12v is don't grind on it very long at a time if it won't start. I guess starter really doesn't care if 6 or 12v. Check out Duey's page    http://dueyschutter.freeservers.com/