I just did a 12 volt conversion on a Dune Buggy. There are just a few parts needed to do the conversion. You need a 12 volt generator or an internally regulated alternator. A 12 volt coil, if you do use a generator you’ll also need a 12 volt voltage regulator. You need to install a new alt/gen. Stand; if you use an alternator you’ll need a new fuel pump. The alternators require the use of the later style fuel pumps that are angled. The hard part is getting the fan housing moved just enough to remove the old generator and fan. Usually it is easier to remove the carburetor, this will give you just a bit more room to work.
Once you get the 6 volt gen and fan out, you’ll need a 36mm socket to remove the big nut on the back of the fan. Then remove the two 10mm nuts holding the backing plates on the generator. You’ll need a 12 volt backing plate to re-assemble the new gen or alt. Don’t forget the small ring in between the 2 larger backing plates. The hard part here is keeping the key on the shaft of the gen/alt in place while you fit the fan adaptor. Once that is in place use a few shims to set the fan clearance. This can be tricky; too many shims and the fan will rub in the fan housing. Not enough and the fan will rub the backing plate.
Now re-install the gen/alt assembly back into the housing. Re-set the housing on the engine, tighten the side bolts, install the strap and you are ready to move on to the next step. While you have the carb, off you can install a new 12 volt choke. You may have to get a 12 volt solenoid if the carb is equipped with one.
The wiring is fairly simple. On a generator simply mount the voltage regulator on the fan housing or on firewall near the engine. The 12 volt regulator is wired the same as the 6 volt. Depending where you mount it you may have to lengthen the wires. Sometimes I like get fancy and mount them under the back seat, just like a later model. That is only possible if you have a lot of time to run extra wires trough the body.
That is why I prefer to use an internally regulated one wire alternator. The wiring is so simple. On a 6 volt car just connect the 2 big red wires to the positive terminal on the alt. And hook the small wire to spade terminal and you are done. Make sure you insulate the big red wires. They are sticking up and always seem to get touched by something and give a nice big arc. Zap!
Next go under the hood. You’ll need 12 volt flasher. Don’t worry about the dimmer switch, on an early bug the dimmer is just a switch and not a relay.
The wiper is possibly the hardest part of the 12 volt conversion. The 6 volt wipers don’t like being hit with 12 volts. They go crazy! You can install an inline voltage drop on the wiper motor. These work okay. I have noticed that Wolfsburg West now has new 12 volt armatures to install in your 6 volt wiper motor. This is a great thing but is a little more labor intensive. Not too pricey, I think they are around $35 dollars for the armature.
Now all we have left is to change out all the light bulbs. You’ll need; 2 head lights, turn signal bulbs, brake and tail light bulbs, and instrument bulbs. Oh don’t forget the license plate light.
Now install your new 12 battery and look at your brighter head lights and faster blinkers.
There it is.; a pretty simple conversion that really makes your Volkswagen a little easier to drive.