Ballast Coil and Resistor Repair

Older cars managed their electricity differently than more modern cars. This involved using a ballast coil and a resistor to protect the starter from overexposure to electricity. Modern cars more commonly use an ignition coil but classic car repairs may involve replacing the ballast coil and resistor. The steps below will help you learn how to make this repair yourself.

Directions

1

Gather the Materials

This repair requires little in the way of parts. You need a new resistor and coil. You also require 18 gauge wire and a set of size ten terminal rings. To be safe, you should get enough 18 gauge wire to stretch from the front of the car to the back and halfway to the front again.

2

Get the Tools

There are two major tools you need to set up a ballast resistor and coil. A wire stripper is essential for this repair. Without it you cannot safely and satisfactorily strip the coating from the electrical wire. You also require pliers, either round nose or flat nose. Pliers are required for crimping the exposed wire around metal parts.
* a As well as tools you need safety gear to ensure your safety while completing the repair. You need safety goggles and thick, protective gloves. Gloves can be made from leather or synthetic fabric but should provide a snug fit to allow you to successfully operate your tools and maneuver small objects easily without impeding your dexterity too much. Another important safety item when dealing with any electrical repair is a pair of good quality insulated boots. The boots should have a thick, sturdy rubber sole to provide proper protection against accidental electric shocks.

3

Disconnect the Battery.

After putting on all your safety gear, you need to finish off taking care of the safety aspects before you begin the actual repair. This repair is fairy simple but safety is still crucial. Like all electrical repairs, the battery needs to be disconnected to prevent shocks. This is done by taking the cord off the negative battery terminal and making sure the wires don’t touch at all while the repair is underway.

4

Start Running the Wire

Run enough of the 18 gauge wire through the car so that it reaches from the engine to the passenger compartment. It would be best to not cut the wire until this is done, because you need two pieces to complete the repair and if you estimate the length incorrectly, you will run out of wire. Cut the wire so that it comfortably stretches from the front of the car to the steering column.

5

Strip the Wire

Strip off about a half inch from each end of the wire using the wire strippers. Make sure you strip the wire with a motion away from your body to avoid injury. Be sure not to strip off more than a half inch as you do not want to remove too much insulation. Also ensure that the bared wires are in good condition, with no splits or partial cuts from the wire strippers.
* a If you find that the bared wires have received damage from the wire strippers, cut them off just after the point of damage. Then proceed to strip another half inch from the insulation. Using damaged wires leaves you with a weak connection and does not produce good quality or lasting results.

6

Connect the Wire to the Ring Terminal

Crimp the stripped end of the wire onto one of the ring terminals. Connect this ring to the ignition switch terminal.

7

Connect the Wire to the Resistor

Crimp the loose end of the wire onto one terminal of the ballast resistor using your pliers or crimpers. The other terminal needs to stay open at this point.

8

Connect the Resistor

Take the remaining length of wire and cut a piece that measures from the final placement of the resistor to the coil. Strip half an inch of insulation from each end. Then, connect one end of the wire to the vacant transistor terminal. Connect the other end of the wire to the "positive" end of the coil.

9

Connect the Gauge Wire

Locate the gauge wire coming from the distributor body. Connect this wire to the "negative" end of the coil. At this point you can safely reconnect the battery and the repair is complete.

The technology of the ballast resistor may be old news for a car mechanic, but cars old enough to use them are still on the road. You can still see many of the cars that need these devices in a classic car show. If you are planning to repair or install this equipment, be careful. Even though it is a simple repair, it still requires caution because it involves the electrics of the vehicle.