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Weighing the Benefits Of Ford Tractor Ground Systems

By Tom Seest

What Are The Pros and Cons Of Old Ford Tractors?

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Ford tractors originally used a positive ground system until switching to 12volt in the mid fifties, although this method works just fine but is less forgiving of bad connections than modern systems.
Transitioning to negative ground is easy: just switch the battery cables and some gauge connections (including your amp meter). A bottle of silicon spray lube is also handy to have handy!

What Are The Pros and Cons Of Old Ford Tractors?

What Are The Pros and Cons Of Old Ford Tractors?

Uncovering the Ford Tractor Battery Connection Mystery

First and foremost, ensure all wiring connections are tight. Look out for cracked insulation, loose splices, bare terminal spots, or any other signs of deterioration; vintage tractors typically use more current than modern vehicles, and open or corroded connections may not tolerate their extra voltage as easily.
Before beginning, check the ammeter to ensure it is functioning as it should be. If it shows negative readings, someone has installed items backward, causing irreparable damage to components like the Amp Gauge and Voltage Regulator. Fixing this is simple – disconnect one ground wire and hook it to another terminal of your ammeter, then reconnect both cables for further testing; if it reads as it should, then you are set!
Repolarizing the generator field poles can also be done easily and quickly by replacing the original cutout relay with one designed to run on 6 volts. Also, disconnect your field wire from its regulator, jumpering it to the BAT terminal of the generator (it will spark briefly, but this only energizes internal grounded coils of Genny with maximum field power)
If your tractor features lights (headlights, tail light, and/or work light), it is advisable to replace their bulbs as soon as possible with high-quality 12-volt bulbs of higher grade and use British practice by attaching a label warning of its positive ground nature near its battery.
Converting to digital is not difficult but does require time. For the best results and to reduce mistakes and downtime, use professional-style cast copper compression terminals instead of the cheap lead ones commonly available at auto parts stores; these provide full 360deg contact with cables while being sealed in heat-shrink tubing to protect from corrosion – QuickCable at NAPA has them for $3 to $8 each, depending on cable size.

Uncovering the Ford Tractor Battery Connection Mystery

Uncovering the Ford Tractor Battery Connection Mystery

Amp Gauge: How Does It Affect Old Ford Tractors’ Ground Systems?

Ammeters are essential components of charging circuits, providing a clear picture of how much current your alternator is producing. You should ensure the wiring is done correctly to ensure it functions as intended and prevent it from burning out or starting a fire.
An ammeter requires all electrical components to have specific polarities; its negative side must connect to the ground, while its positive side should go directly to the battery terminal. Wiring it wrongly could damage both components. Furthermore, you must be mindful of which voltage type your ammeter requires in order for proper functioning – different types require different amounts in order for their full function. Likewise, make sure your tractor uses one with suitable specs!
Before connecting an ammeter, first, disconnect the battery ground cable – usually green wire connected to the regulator’s ground terminal – then connect an 8 AWG (10.0 mm2) wire directly from the battery positive terminal or alternator terminal connected with the starter solenoid to its left terminal of the ammeter.
Your old Ford tractor may present you with a maze of wires that is difficult to see through, some wrapped with tape; it is essential that these be removed so each individual wire can be seen properly and looked over for wear or damage. In order to protect its wiring against moisture damage, it may also be beneficial to use some split corrugated plastic covering to shield each individual wire.
Some older 6-volt wiring systems on Ford and other tractors can be difficult to polarize. You might be able to tell by looking at the voltage regulator terminals; typically there will be an independent terminal (BAT), with another close by (ARM). Also, check generator polarity by connecting probes from a multimeter to both terminals and measuring resistance readings; if it is properly connected, the readings should be high; otherwise, they’ll be low.

Amp Gauge: How Does It Affect Old Ford Tractors' Ground Systems?

Amp Gauge: How Does It Affect Old Ford Tractors’ Ground Systems?

How Does the Ignition Coil Impact Old Ford Tractors’ Ground Systems?

Negative ground systems allow electrons to pass from hot surfaces, such as the center electrode of a spark plug, to lower energy surfaces, such as its arm, before returning through its coil (negative polarity). Doing this allows electrons to avoid metal erosion that would result in large spark gaps and reduces ignition coil high-tension output output.
Positive ground systems require connecting the negative terminal of a coil negative terminal directly to the battery while its positive terminal connects with a distributor/switch. If you switch over to negative grounding, be sure to switch the connections on both coil and amp gauge so they have their proper polarities.
Modern automotive and tractor coils often feature polarity markings on their terminals to facilitate switching them over to negative ground systems easily. Older coils may not have these markings but still can be easily repolarized as long as care is taken not to touch spark plugs or engine grounds while doing it – your tractor should thank you!
Repolarizing an amp gauge is straightforward. Simply remove and replace its connector with one featuring a “minus (ground) mark”; attach this new “minus” connector to both negative battery terminals as well as positive battery cables – and voila – you are ready!
If you want to repolarize the generator field, you can follow a similar strategy as used with batteries: disconnecting and briefly jumping the field wire to the battery terminal on the voltage regulator (this may spark); this will energize internally grounded coils of the generator field and give maximum field power briefly.
if you are uncertain which side of the coil connects with the distributor, a multimeter can help identify it by connecting probes to both its large terminal and the body of the alternator – this should display high resistance with a positive probe on the large terminal and low resistance with a negative probe on the body – with each probe showing different amounts of resistance on the large terminal.

How Does the Ignition Coil Impact Old Ford Tractors' Ground Systems?

How Does the Ignition Coil Impact Old Ford Tractors’ Ground Systems?

Uncovering the Mysteries of Ford Tractor Voltage Regulation

A voltage regulator features two terminals marked BAT and ARM. The BAT terminal connects to one of the battery charging wires, while the ARM connects to both ground wires on a harness as well as the ignition coil. The field wire is connected at its other end to the small terminal on the regulator; field windings in the generator armatures are ground through the field wire. When the engine starts up, magnetic fields created by the engine running can cause it to overheat; therefore, to prevent this, disconnect the field wire briefly from the regulator and touch it briefly with the BAT terminal for one second – a slight spark may ensue, but this should not cause serious harm.
One large yellow wire travels from the regulator to one post on your terminal block if your tractor features the older 3-post type; otherwise, it should go to either of its 2-terminal posts. From there, it connects with one smaller yellow wire, which connects directly with the armature on your generator via an attached piece of metal that protrudes from its side case – for maximum reliability, it would be wise to install a more modern style armature connector as they may become disconnected over time.
There is also a third, smaller yellow wire that connects the generator armature to a small terminal on the starter solenoid and serves as the start wire – this wire connects directly with its other terminal on the solenoid connected to the tractor frame.
There are also other terminals on the voltage regulator that aren’t utilized; typically, these terminals are for optional lighting. Lighting wiring isn’t included with the main harness; dealer installation of lighting must be desired if desired. If your tractor features a light switch, a separate wire will connect from the terminal block to the light switch before continuing onto headlights and tail lights via switch connections.

Uncovering the Mysteries of Ford Tractor Voltage Regulation

Uncovering the Mysteries of Ford Tractor Voltage Regulation

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