Rewiring 48 Cub with modified ignition system

[mcwinter]

With my hood removed for generator pulley repair, the wiring is going to be replaced also. The headlight wires have broken insulation showing bare wire in spots. From what I can glean reading related topics, this cub has the original style generator (1101355) for this year but does not have a magneto. Apparently, an upgrade was done to install a battery ignition system. I do still have the 4 position light switch (LHDB) but have a newer ignition switch (two wires with power through the switch). I have ordered the wiring harness for my model cub.

I had some work done on the tractor a few years ago including generator rebuild. I don't see a wiring diagram specific to this configuration (original generator with cutout, and battery ignition system). The tractor runs and I can replicate existing wiring but I would like to compare existing with a diagram for this setup.

Can someone confirm the configuration I believe I have? Also, will the original style (1948) wiring harness work to rewire this tractor? Which wiring diagram can I use to ensure proper wiring for this configuration? Thanks

[Jim Becker]

Yes, your system appears to be a stock early style system with a later conversion to battery ignition. You use the early diagram but make one change. The grounding wire from the ignition switch to the magneto is repurposed to feed power form the ignition switch to the ignition coil. An additional short wire is added from the ammeter (generator side) to the ignition switch. There is a little diagram that shows this change in the Battery Ignition Package Installation Instructions. This manual can be found in the PDF Manuals at:
Farmall Cub/Cub Optional Equipment Manuals.

[butchs38]

The only thing I did different was I wired the headlight switch through the ignition switch so if I forget to turn lights off they will also go off with ignition switch. And replaced fuse with a breaker.

[John *.?-!.* cub owner]

Butchs38 has you covered, use his diagram. You will need to add the wiring for the ignition switch to the one you ordered. If your light switch resister is good, the wire going from the F of the gen to the F of the cutout does not need to be there. If the flat resister on the light switch is bad or missing, leave the wire where it is and also connect the one that came with the wire harness. Having both wires in place with the resister on the light switch being good, will not be a big problem, it will just mean that rather than charging at 2 amps on L it will charge about 4 amps. Not a problem unless you run it all day long on a regular basis.

[mcwinter]

Thanks for your help. Looking over the existing wiring, the mechanic who worked on the generator last did not wire per the diagram above. There is a short wire from F on gen to F on cutout as John mentioned and you can see in the photo. The lead from the light switch field resistor to the F gen terminal is not landed, and just taped up. Would running in this configuration cause any damage? Does this indicate a faulty field resistor on the light switch?

[Glen]

Hi,
If you are wanting a more original appearance for the wiring on the right side of the engine, the Battery Ignition unit on Cubs originally had a different bracket for holding the coil, and a bracket that went on the 2 holes on top of the Battery Ignition unit, to move the coil to the right slightly, to clear the generator bracket.

Below are listings at TM Tractor. There are pics of where the bracket goes.

http://www.tmtractor.com/new/el/947fp.htm

I don't know if the coil bracket fits the coil you have.

http://www.tmtractor.com/new/el/693fp.htm

Below is a pic of the newer style coil mounted the original way. It makes the coil be under the hood.

[butchs38]

Could be a faulty resistor bad switch or switch is not grounded. If the switch housing is not grounded it will not charge (it drove me nuts one time). It should ground where switch meets dash and dash has to be grounded also. That may be why it is wired the way it is.

[John *.?-!.* cub owner]

It will not hurt anything, but repeated starts and short run time will result in the battery running down. The mechanic may not have realized that was a cutout and not a regulator. That would be correct wiring for a regulator.

[Jim Becker]

. . . The lead from the light switch field resistor to the F gen terminal is not landed, and just taped up. Would running in this configuration cause any damage? . . .

The generator F connected only to the cut-out F will not hurt anything. The effect is to have it hard-wired to low charge, about 1.5 to 2 amps at full speed.

I just noted the previous comments on the way the ignition coil is mounted. The lack of the Cub-specific bracket brings into question whether the entire unit came from another model. Don't worry about it until you get past the wiring tasks but you do need to verify which distributor it is. There is a code stamped into the flange of the distributor housing, right by where you unclamp it to adjust the timing. The Cub distributor will start with a "D".