Seeking advice on re-wiring 51 Cub

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Joined: Sat Mar 12, 2022 11:59 am
Zip Code: 75455
Tractors Owned: 1947 Cub / Hydraulic Lift / 42" Wood Mower / This is a project Cub as the old man (a Cub Restorer) told me it has low compression and needs an overhaul, which I will do myself.

1951 Cub / Hydraulic Lift/ Cultivators/ Planter & Fertilizer. This tractor was in service until 3 years ago. First task to clean, perform all recommended services on it. I got this Cub in Service for the Spring, Summer, Fall of 2022, Mostly used the 144 Cultivator (plant guards acquired in Winter of 2023) Working on Installing Rolling Cultivators Spring of 2023. I have installed and used my Mold Board Plow with Colter and used it to break up a patch once.

Small Ford F-1100 4x4 for some gardening uses.
Location: Northeast Texas

Seeking advice on re-wiring 51 Cub

Postby WPMinor » Tue Mar 22, 2022 5:48 am

I recently purchased a cub with points/distributer, that has set in the barn for the last several years and was running and plowing prior to that. It is currently set up as 12 volt, Positive Ground. Extremely clean fuel tank/supply even in the carb bowl. Good compression but no fire. After I picked up a TSC tune up kit and new set of plug wires, I discovered there was no voltage to the coil so checking switch etc, I found that several wires were brittle and broken at the amp meter and to the switch. It has a single wire alternator on it. I have no clue to determine which (if there is one) wiring diagram for this particular set up. The wiring was sloppily done on it decades ago and nuts on the amp meter were frozen solid. The coil that came on this cub says 12 volt with a resistor printed on it but I do not find a resistor anywhere in the circuit. Since it obviously ran for years as is, my thoughts are to replace all wiring and loom it together myself from the panel to the front (one wire) head lights which did work. Am I missing something here or on the right track. I am a little baffled at the lack of a resistor if required for this set up.

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Re: Seeking advice on re-wiring 51 Cub

Postby Pap » Tue Mar 22, 2022 7:36 am

Welcome to the forum WP.
I am sure some of the folks on here can help you with this I can't.
But good luck with your project and Enjoy Your Ride.
Are We Having Fun Yet ? :D
'47 cub ( Err Err )

Gary Dotson
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Re: Seeking advice on re-wiring 51 Cub

Postby Gary Dotson » Tue Mar 22, 2022 7:41 am

Please confirm the positive ground statement! Although positive ground 1 wire alternators can be had, they are very rare and I’ve never seen a 12 volt positive ground unit. About 99 percent of people converting to 12 volts, also switch to neg ground. I’d be very suspicious if I encountered this. Does the coil say “ 12 volt internal resister” or does it say “12 volt external resister required” ? If it is internal resister, no additional resister is needed, otherwise, you’ll need to add one. If your tractor is actually positive ground, I doubt you’ll find a specific diagram for it, although simply swapping all the neg. And pos. Indications will pretty much get you there.

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Re: Seeking advice on re-wiring 51 Cub

Postby Stanton » Tue Mar 22, 2022 8:10 am

Welcome to the Forum! Many of us have bought tractors with funky PO mods.

Take some time and read through a few threads to acquaint yourself with the Forum:

Don't know if you have any paperwork to your Cub, but after you’ve logged your 2nd post on the Forum, you'll have access to the all the PDF Manuals on this site. There’s a few ways to do that:
  • From a desktop or laptop, go to "Quick Links" in the upper left corner of your screen. Hit that and a pull-down appears where you'll find "PDF Manuals".
  • You can also go to “Cub Info” in the upper toolbar, then hit “Rudi’s Manuals”. From there, you can access a variety of information.
  • If you're using a phone, go to the "Links Directory" (second category down the main page). Once in "Links Directory" , scroll down to the second section "Tractor Parts & Manuals" and you'll find them there.

You'll be able to download an Owner's Manual (very strongly recommended) and any service manuals that interest you. Implement Manuals are also available.

Might also enjoy reading through this thread (even though it’s for a Cub, much can be applied to any tractor just brought home): What to do with a Cub you just brought home

There are a lot of good threads dealing with Cub repair and maintenance in the How To Forum. There’s a whole section dedicated to electrical, including wiring diagrams. Located here:

We’d encourage you to take the Safety Test located in the Safety Forum:

Take some pictures of your tractor and post them, we’d like to see them.

  • Pictures are limited to 500 KB file size. Use an image reducer app or program to downsize pics.
  • When you have a specific question, start a new thread in the appropriate sub-forum.
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Glad you joined us.

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Re: Seeking advice on re-wiring 51 Cub

Postby 69ranger » Tue Mar 22, 2022 8:58 am

Welcome to the Forum! Happy to have you with us. There is a lot of knowledge here, and many willing and helpful folks, that are happy to help a new guy on his adventures in this fun hobby.
Good advise above, check a few things out, and don't be afraid to dive in to this. The wiring is pretty easy on these little tractors, and can be repaired, replaced or built from scratch from bulk wire, available at most auto parts stores.

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Re: Seeking advice on re-wiring 51 Cub

Postby Jim Becker » Tue Mar 22, 2022 11:40 am

To add on to what Gary said, I strongly suggest you not try starting it or even hooking up any wires until you are sure what components you have. I am mainly questioning what you have for a generator/alternator. Simply connecting a battery backwards can damage an alternator. Based on the information you have already posted, I assume you have the hood/tank off the tractor. Take a close look and determine whether you have a generator or alternator and what voltage it is intended for. An original tag would help id it. If you are unsure, post a picture.

It is possible somebody put in 12-volt battery and coil but didn't change the generator. This scenario is more likely than installation of a positive ground alternator. Once we know where you are really starting from and where you want to end up, we can give better suggestions on rewiring.

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Re: Seeking advice on re-wiring 51 Cub

Postby Clubless » Tue Mar 22, 2022 12:44 pm

The best advice I can give you is to post pictures of the engine area of your cub. I am always amazed what information these guys can gleam out from pictures and provide you more detailed directions.

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