Farmall Cub

Hi folks. I put a new battery in my 1950 Cub and as soon as I hooked the positive lead to the battery smoke came out from under the hood. The tractor is new to me and it was converted from a six to a twelve volt system. Negative ground. I've momentarily tried swapping the battery connections and the ammeter swings all the way from one direction to the other when the leads at the battery are reversed. It stays 'pegged' in one direction or the other either way.

The battery was dead when I bought it but the seller could get it to run by hand cranking it. It does run just fine whether hand cranked or when I start it with the battery.

I'm pretty sure I blew the fuse as the lights no longer work and my hands are too fat to get another fuse in there to see if the damage is limited to the fuse. Love the little tractor and am nursing it back to health with all of the various lubricants it has been deprived of.

Any suggestions?

Since it smoked when you connected the battery, I suggest removing the hood and inspecting the wiring for a bare spot, also look at the wiring diagrams in the manual sections and compare it to them. Since the previous owner was starting it with a crank rather than installing a battery, he probably knew there was a problem. Here is a copy of the most common wiring used for 12 volt conversion. Since the PO was starting it without a battery I assume it has a magneto, so you will not have the ballast resister and the wires connecting it. Instead you will just have a wire from the side of the magneto to the kill switch that grounds the magneto to stop the engine. Another possibility is a bad alternator.



diagram courtesy of Farmall Bob http://s101.photobucket.com/user/farmal ... t=4&page=1

Thank you for your help and another question if you would. I intend to rewire it tomorrow and am curious how critical the gauge of the wire is for the under hood wiring. Can I substitute 12 for 14 or 16 if Tractor Supply doesn't have what I need?

Once again, thank you and I wish I had become a Cub fan a long time ago. These things are great!

Posco wrote:am curious how critical the gauge of the wire is for the under hood wiring. Can I substitute 12 for 14 or 16 if Tractor Supply doesn't have what I need?

Yup. You can use 12 wire gauge instead of the higher numbered, smaller diameter wire. No problem.

If you have an alternator you will need to use 10 gauge wire from the alternator back to the starter terminal connection.

Local hardware store carries 50 foot length spools of multi-strand electrical wire and wire terminal ends. They also have huge spools of wire and will cut off any length needed.

I believe that you can always substitute larger (i.e. smaller gauge number) wire without problem.

Thank you. You guys are great.

Don't forget your diode going back to the switch or it won't shut off....Radio shack item....

I think the closest Radio Shack is forty miles away. Auto parts store?

pickerandsinger wrote:Don't forget your diode going back to the switch or it won't shut off....Radio shack item....

You may or may not need the diode or lamp depicted in the wiring diagram. The purpose of the diode, a separate switch or the light bulb is to prevent the alternator from back feeding the ignition system. It is going to depend on which alternator is present, how the tractor's electrical system is wired, magneto or distributor.

As it's wired now, there is no diode present that I'm aware of and until i pull the hood I can't tell what alternator I have...if that's what you're getting at, Eugene.

I'm no electrician and I'm confused about something. Wouldn't the alternator make the magneto unnecessary or vice versa? Does one 'drop out' when the other is engaged?

I do appreciate your guys help.

Posco wrote:Wouldn't the alternator make the magneto unnecessary or vice versa? Does one 'drop out' when the other is engaged?

You need both. The alternator charges your system. The magneto acts as a distributor and will also allow you start a Cub with a hand crank if the battery is dead or missing. If you remove the magneto you will need to install a distributor.

Posco:

G'day to you and congrats on acquiring your new to you '50 Cub. The guys have been taking good care of you with your questions and I don't have a lot to add. I did experience the smoking phenomenon on my '47. Turned out to be some of the wiring at the light switch along with the resistor burning up. Rather quick fix.

However a couple things immediately jump out at me. You haven't pulled the hood so you really are not sure what you have. Most conversions usually entail the battery, coil, ballast resistor and light bulbs .. basically about it. Normally the generator is left in the system when a basic conversion is done. So you need to ensure that you have either a generator or an alternator before you start spending coin on parts. If it was just a basic 12 volt battery conversion on a Mag equipped tractor you have choices. You can go back to the original 6 volt positive ground .. it will require removing the ballast resister, replacing the light bulbs with 1133's and of course a new Group 1/19L 6 volt battery. Leave the existing gauge of wire in place, replace any damaged sections with an identical gauge. If you wish to keep it 12 volt, then 10 gauge wire is suitable. I am not a fan of 12 or 14 gauge on an ignition system. For cars/trucks it is different, but for tractors I prefer the heavier gauge wire.

This schematic would be more correct for your '50 Cub especially if there was no alternator conversion. With the 12 volt conversion you would have the ballast resistor as indicated in the previous schematic.



As I always mention, we have a lot of resources available to our members and I always encourage members to follow the links below and read the materials therein. These will go a long way to helping you out.

to Farmallcub.com Forum Family. And you have come to the right place for all things Cub related. If you click on the Site Rules, Regulations, & Important Information, it will point you to the Welcome Wagon wherein you will find links to many useful sites and topics. One of the most important resources are Owner's Manuals, Parts Catalogs and Service Manuals. The Cub Manual Server is the home of the jpg versions and the [url=http://www.farmallcub.com/[ Sorry, direct links to manual section is not allowed. ]/index.php]PDF Manuals[/url] -- well the pdf's of course Enjoy!.

Hope this helps a bit. Keep us posted on your progress.

Rudi wrote:Posco:

G'day to you and congrats on acquiring your new to you '50 Cub. The guys have been taking good care of you with your questions and I don't have a lot to add. I did experience the smoking phenomenon on my '47. Turned out to be some of the wiring at the light switch along with the resistor burning up. Rather quick fix.

However a couple things immediately jump out at me. You haven't pulled the hood so you really are not sure what you have. Most conversions usually entail the battery, coil, ballast resistor and light bulbs .. basically about it. Normally the generator is left in the system when a basic conversion is done. So you need to ensure that you have either a generator or an alternator before you start spending coin on parts. If it was just a basic 12 volt battery conversion on a Mag equipped tractor you have choices. You can go back to the original 6 volt positive ground .. it will require removing the ballast resister, replacing the light bulbs with 1133's and of course a new Group 1/19L 6 volt battery. Leave the existing gauge of wire in place, replace any damaged sections with an identical gauge. If you wish to keep it 12 volt, then 10 gauge wire is suitable. I am not a fan of 12 or 14 gauge on an ignition system. For cars/trucks it is different, but for tractors I prefer the heavier gauge wire.

This schematic would be more correct for your '50 Cub especially if there was no alternator conversion. With the 12 volt conversion you would have the ballast resistor as indicated in the previous schematic.



As I always mention, we have a lot of resources available to our members and I always encourage members to follow the links below and read the materials therein. These will go a long way to helping you out.

to Farmallcub.com Forum Family. And you have come to the right place for all things Cub related. If you click on the Site Rules, Regulations, & Important Information, it will point you to the Welcome Wagon wherein you will find links to many useful sites and topics. One of the most important resources are Owner's Manuals, Parts Catalogs and Service Manuals. The Cub Manual Server is the home of the jpg versions and the [url=http://www.farmallcub.com/[ Sorry, direct links to manual section is not allowed. ]/index.php]PDF Manuals[/url] -- well the pdf's of course Enjoy!.

Hope this helps a bit. Keep us posted on your progress.

You guys are great and allow me to give you an update. It does have a distributor so I don't know what kind of a hybrid I've got. I went to Tractor Supply shortly after I posted this morning and picked up some bulk battery cable and an assortment of 10 gauge wire, connections and the like.

I wired it up the way it was...negative ground, ran a new cable from the battery to the starter and it took right off and my ammeter is holding in the middle. Baby steps. I think maybe the ride home on the trailer might have chaffed the wires which were already in poor condition. I'll still tap you guys for info when I dig deeper into other areas like polarizing the generator, etc..

As an aside. The seller told me the tractor was routinely serviced year to year by a guy who knows tractors. Forgive me for not yanking the oil dipstick when I initially surveyed the Cub. It was three quarts low. The gasket on the oil filter looked like it must have been put on in 1912. It was shot. The steering gear housing was bone dry and the transmission had 30 wt. gear water in it. Mocha! I pulled the rear axle housings and they were fine but I emptied them and put new gear oil in place. Drained the transmission and did the same. I'll be looking for some Hy-Trans when I get my courage up. Still a lot of fussing to be done under the hood.

The lugs on the front tires seem to have been loosened last just prior to the 1912 gasket change on the oil filter. I'll be ordering bearings and whatnot when the wife comes to understand what a gem we'll have.

Thanks guys, you're a nice group of people. The world needs more of that.

Well then, the Battery and Ignition Packages for Tractors will probably be useful then

Posco wrote:As an aside. The seller told me the tractor was routinely serviced year to year by a guy who knows tractors. Forgive me for not yanking the oil dipstick when I initially surveyed the Cub. It was three quarts low. The gasket on the oil filter looked like it must have been put on in 1912. It was shot. The steering gear housing was bone dry and the transmission had 30 wt. gear water in it. Mocha! I pulled the rear axle housings and they were fine but I emptied them and put new gear oil in place. Drained the transmission and did the same.

This is pretty normal. One thing I have learned is to not trust much of what a PO says about the Cub. I go through it myself and see what is what before it gets put to work. A little Preventive Maintenance on acquisition can save a lot of heartache and wallet pain down the road.

Posco wrote:when the wife comes to understand what a gem we'll have

It won't take her long to appreciate that. One time getting seat time and you may have to find yourself your own ride Ahhh.. yeah .... it does work that way

Posco wrote:Thanks guys, you're a nice group of people. The world needs more of that.

This what we have always aspired to as a community. Help other folks with their toys as well as welcome them to the best forum community on the net

Posco wrote: I'll be ordering bearings and whatnot

Pull the bearings and clean them before ordering anything - They may just need to be re-packed.