Triumph Repair: TR4 Earth, negative earth, heater fans

Question
Hi Howard, I have just got a 62 TR4,it has negative earth, but the manuals seem to indicate it should be positive. There is quite a lot of damage to the wiring, looks like its shorted out at some time, however most of the electrics work ok, has someone changed the polarity or is negative earth correct and if it is working does it matter? by the way this is a left hand drive from America

Answer
Hi Richard,
Any car with a generator can be changed to either one. However, several things MUST be done to change the polarity of a car. The generator MUST be polarized to match what polarity a person wants on the car and the battery/s must be connected up to match. Also the polarity of the ignition coil must match the polarity of the car. Even though most heater fans will blow air in either direction, they only blow the most air when the polarity is set to match the battery.

The main reason most people change the polarity of a car is to use a late model radio or CD player.

If your charging system is working ok then all you need to do is to look at the ignition coil and see that the distributor side of the coil matches the battery ground. You can test the heater fan by placing a piece of paper near the defrost vent and turn the defrost on and watch how the paper moves, then reverse the two leads of the fan motor and do the same test. One way will blow harder than the other.
Howard