CHANGING ELECTRICAL POLARITY
When fitting a new or rebuilt generator to your Mini, certain instructions will usually be found with it. These instructions advise the course of action to polarize the unit and are the same instructions for changing the cars electrical system from positive to negative earth or vice-versa. They are as follows:
1. Place the car’s battery in front of the car.
2. Remove the car’s front grille.
3. With the generator mounted in its regular position, slacken the adjusting nuts and remove fan belt.
4. Remove the two (2) wires connected to the generator.
5. Run a wire from the negative terminal of the battery to a clean point (paint free) on the body of the generator.
6. Connect a wire to the positive terminal of the battery and hold the other end against the small generator connection, marked ‘F’ for 2-3 seconds. Repeat this action 2-3 times.
7. The generator is now re-polarized.
8. Reverse the two (2) low tension wires connected to the coil so that the negative terminal is wired to the distributor.
9. The cars electrical system is now negative earth.
The procedure is the same when converting from a negative to positive system. Except that the wiring connections would be reversed.
Refit the fanbelt, adjust the generator, replace the two (2) generator wires, refit the grille and mount the battery in a negative earth position.
You may find the battery cable connectors require reversing. These can be re-soldered or replaced with clamp-on type connectors #5650 and #5651.
Points to Watch
After fitting a new generator, it is advisable to check the condition of the voltage control box, as a fault on this unit is a common cause of generator failure. Make sure the points are opening and closing correctly. If they require cleaning, hold them shut manually as a piece of fine glass paper is drawn between them (DO NOT use emery or carborundum paper).
The standard S.U. Electric Fuel Pump will operate on either a negative or positive earth system. Other makes of pumps may not. Check with the manufacturer. This may also be the case with certain accessories, i.e. radio.
If the car is fitted with an ammeter, reverse the two (2) main cables on the back of the instrument.
If the car is fitted with a Smiths Electric Tachometer, it will have to be rewired according to the original wiring instructions. If fitted with any other make of electric tachometer, check the original wiring instructions or consult the manufacturer.
Be sure all affected accessories are disconnected BEFORE changing polarity.