Isabella 12 volt conversion

Any 40ah battery or above would be suitable that fits in the space and has the + and - connections in the right place As modern batteries are not as deep as the original type bracket modifications may be needed or packing, also check the terminals do not touch the underside of the bonnet on closing. Original looking battery's are available at a premium.

The simplest thing is to fit a Bosch alternator being mindful the lower mounting bracket will need modifying, packing washers may be required to line the belt and the top bracket has to be the correct side. Early Ford Sierra's had the correct one. A LUCAS alternator A127 left hand fitting will also work. As the engine pulley is large a larger type pulley should be fitted on the alternator to prevent over speeding .A new belt of different length and a longer sliding adjustor may be needed.
The red wire from the old removed regulator can be extended and connected along with the warning light (connection 61 old regulator blue). take extra care with the red wire as it is connected to the battery, carry's 30+ amps and is in close proximity to the exhaust manifold/downpipe. New, remanufactured Lucas 18ACR (35A) are obtainable. A later Lucas A127 (35A to 70A) can also be used.
A larger 3”o/d alternator pulley reduces the alternator revs to 1.9 x engine speed and so avoids over-speeding.

Generator for original look
If a generator is to be used a 12 volt Bosch one could be obtained for originality.
Bosch part no. 0. 101 206 151 (EG -> 14V 25A 25) or 0. 101 206 079 (EG -> 14V 25A 25) or 0. 101 206 100 101.The Bosch voltage regulator that looks like the original is 30 007 (0 190 350 049 -740) look alike alternators are also available.

Lucas generators have been fitted in the past with there matching regulators and there are more readily available in breakers yards and were used in most British 1960s cars. Alternators are now being fitted inside dynamo cases so the best of both worlds can be had for example.

Starter motor
The 6 volt Bosch starter is suitable for testing although the solenoid is under much more stress. A 12 volt BOSCH 1.5 KW starter motor 0 001 107 062 or Aftermarket type RNL2250 will fit.
Any 12 volt coil can be used in place of the 6 volt one e.g. BOSCH 0 221 111 9027 Blue coil no ballast resistor or Red coil BOSCH 0 221 111 9030 for P100 with ballast resistor no other modifications are required to the ignition system.

Just use a 12 volt 3 pin type the flasher is under the drivers side dashboard.

Wiper motor
The 12 volt SWF wiper motor as used on Volvo 245 estates and the like and this can be used complete or just the armature can be replaced. If the armature is to be replaced I would still recommend removing the motor and replacing the grease in its gearbox as after 50 years it will be hard. Double check the mounting position of the motor before removal as its position is critical for normal wiper operation.

käferland produce a wiper motor conversion kit from 6 to 12 volts Part No: 128147 for 39 EUR plus VAT and shipping

6a washer motor

The original SWF motor has its field and armature wired in parallel so by rearranging things so that the windings are in series the motor will run on 12 volts. The SWF washer motor from VOLVO 120 series is a direct 12 volt replacement. Any new type of wiper motor can br used and it is a convenient time to fit electric washers to an Isabella 60 or Combi

Most people just use the existing horn although any 12 volt 2 wire horn can be use
All the bulb types are available at the moment in 12 volt although 12 volt halogen are a problem for the non Bosch Hella reflectors. If the reflectors are to be renewed VW beetle ones fit (käferland reflector Part No: 318105 about 59 EUR plus VAT and shipping) by just modifying the adjustor hole position. don't forget the instrument bulbs.
The cable is of high quality and should present no problems the current at 12 volt being half that if 6 volt.
10 Cigar lighter
The cigar lighter can be replaced with a 12 volt type and white top swapped with a bit of ingenuity.

The early clocks were wind up type but by 1959 6 volt electric types were fitted. It is possible to drop the 12 volt to 6 to run the clock although most clocks are not working as repair will be required any way. It may be possible to have the solenoid coil rewound for 12 volts at the time. or have a more modern quartz movement fitted.

Petrol Gauge
The petrol gauge will require modifying and 12 volts needs to be dropped to about 6. The instrument uses little current so BEX85 6.8 volt zener diode (shown below) and 100 ohm 1/2 watt resistor will suffice please email if you need help.

To remove the dash board there are 4 finger nuts holding it in on the back along with the speedo cable, it can the be removed the fuel gauge is then held by 4 screws.

Heater Fans

The Isabella Coupé and TS has 2 Heater fans so these can be wired in series using one side as a feed and the earth wire extended around the bulkhead to the other fan's positive supply.The 60 and Combi only has one fan so a high wattage resistor is required to drop the operating voltage to about 6 volts. A ceramic ignition Ballast resistor is ideal.

Once the car is converted better lights Halogen or H.I.D. along with a 12 volt radio, sat nav, etc. etc.

IsabellaTS schematic

I will be adding to this page from time to time