From: bjgaed@bb1t.monsanto.com
Newsgroups: rec.autos.vw
Subject: 12 Volt Conversion DONE!
Date: 31 Aug 92 13:36:52 GMT
Organization: Monsanto Company, St. Louis, MO

I recently converted my '64 Ghia from 6 volts to 12 volts, and it was 
something
of an adventure.  I thought I would document what I did for others who 
may be
contemplating a VW electrical conversion.  Sorry about the length, but 
several people have asked me about this.

Engine:

The fundamental difference in the basic engine is the crankshaft on 
the flywheel
end.  It is a slightly different size, so you cannot use 12 volt 
flywheel shims
on your 6 volt crank.  I found this out by trying to put some 12 volt 
shims in
while adjusting the end play; bent them all to hell when I tightened 
the gland
nut.  Be sure you buy a *6 volt* shim set and compare the inside 
diameter to the
shims you took out.  If you are working with an exchange crankshaft, 
get the
shim set with the crank.

The flywheel is the other big issue here.  The 6 volt flywheel has a 
different
number of teeth, so a 12 volt starter will not work. The following 
options were
gleaned off the net (with thanks to all the nice folks who e-mailed me 
info and
hints):

1)  The option I used was to leave the flywheel and starter as is and 
run the 6
volt starter at 12 volts.  The starter won't last as long, but if your 
engine is
well-tuned and starts right away this may be the more economical 
option.  If you
need to replace your clutch and pressure plate anyway, the following 
may be
better for you.

2)  Replace flywheel and starter.  The 12 volt flywheel uses an O-ring 
seal on
the flywheel end that the 6 volt doesn't use.  It may not be in your 
gasket set.
Gene Berg supplies a flywheel specifically for this conversion.  The 
12 volt
flywheel also will not fit in your transmission bell housing.  Several 
people
tellme it is a simple matter to mill off a little aluminum from the 
trans case
to provide clearnce.  You will have to put the engine in, turn it with 
the pully
so the flywheel marks the case, then pull the engine out and mill off 
with a
small grinding wheel where the marks are.  Then iterate until the 
flywheel
clears with the engine mount bolts run all the way up.  This would be 
easier to
do using just the crankcase rather than the whole engine as it is much 
ligher
and easier to handle without the fan, cylinders, heads, etc.  Finally, 
the
starter bushing for the 12 volt starter is different, so that needs to 
be
replaced in the trans housing.  The 12 volt flywheel takes a 200 mm 
clutch and
pressure plate.

Generator and Voltage Regulator:

These should match each other, so try to get them at a parts store 
that knows
VW's.  If you have to mail order be sure to talk to someone on the 
phone so you
get something that will work.  Remember that from now on when you 
order anything
electrical and they ask you for what year and model of car you can't 
tell them
what your car is.   On my Ghia I bought a bug generator and voltage 
regulator,
and then realized I had no place to mount the voltage regulator.  
Possibly a bus
generator would be a better idea for a Ghia?  On a bug, the voltage 
regulator is
under the back seat with the battery, so just replace it.  I mounted 
mine on the
fan housing with sheet metal screws.  This required some wiring 
changes, but a
12 volt wiring diagram helps here.  Also, Bosch had a sticker on the 
new
regulator showing proper wiring.  Also, the 6 volt connections are 
screw-ons,
but some of the 12 volt connections may be push-ons, and some of these 
are
*wider* than the standard ones.  Take the regulator to the parts store 
or an
electronics supply store and find the connectors that fit.  Basically,
connect(Regulator to Generator) DF to DF, D+ to D+, D- to ground on 
the
generator case, B+ to the battery lead, and 61 to the wire for the 
generator
light. 

You will need a 12 volt generator stand.  This is available new, but a 
used one
is fine.  Try to get one with the oil breather tube attached as you 
need a
special tool to change out the tube.  Also, depending on the source, a 
used
stand and oil breather tube may require some sheet metal modifications 
so the
end of the oil breather tube will fit down by No. 2 cylinder.  There 
is usually
no louvered metal piece under the generator stand on a 6 volt as the 
passage
into the case is smaller with a round hole.  VW tech. manual for the 
1200 cc
shows you how to fabricate a baffle for this in case your engine 
throws oil up
the stand and out the breather tube.

On my engine I ran into a clearance problem with the 28PICT carb.  The 
larger
generator *just* cleared the carb, but when I tightened down the carb 
the
accelerator pump ran into the side of the generator and wouldn't 
operate
properly.  I filed off some metal from the pump arm and got a little 
more
clearance, but not enough. Then I got a little more clearance by 
loosening the 4
pedestal nuts, prying the pedestal as for to the right as I could, 
then
tightening them down.  It only gets you about 0.5 mm, but every little 
bit
helps. Finally I got a crowbar and slightly bent the carb neck of the 
intake
manifold to the left.  It only needed about 1-2 mm.  Another option 
would be to
put two or three extra gaskets under the carb, thereby raising it and 
allowing
the pump to clear the curve of the generator.  Also, the 12 volt 
generator seems
to be slightly loner, so bringing the engine up into the engine 
compartment was
a *really* tight squeeze to clear the generator pully.  Try leaving 
the pully
off until the engine is in.  

The only other items on the engine are the coil, which is a straight
replacement, and the carb auto choke.  This is a pricey item, but 
should be
replacable.  I put in a manual choke kit since I had the engine out.  
If you
don't live in a really cold climate and have time to warm up the 
engine per the
Idiot book, you really don't need a choke at all.  If you don't put in 
a 12 volt
choke element be sure you tape the connector so it doesn't ground the 
circuit.


The oil pressure sensor is just a switch, so it doesn't need changing.

Electrical stuff:

This is the most time-consuming part of the job.  

The 12 volt battery for a VW (Size 42, I think) is the same width and 
depth as
the 6 volt, so it fits in the battery tray, but it's a little shorter, 
so you
may have to modify the hold down with some washers so you can tighten 
it down.
The terminals on the 12 volt are on the same side, rather than 
diagonally
opposed as on the 6 volt.  This may require a longer ground connector 
to reach
the engine.

All of the bulbs have to be replaced.  On the outside replace the 
bulbs with
those specified for a 12 volt (find a good manual).  If you can't find 
the
numbers, go by wattage.  On my Ghia I used the following:

Headlights:  6012
Front turn/park lights (dual element in Ghia): 1157
Rear brake lights and turn lights (single element): 1156
Taillights: 97
Lic. Plate light (Ghia): 97

In the dash, all of the 6 volt instrument and warning lights should be 
replaced
by 12 volt instrument illumination lights.  12 volt warning lights are 
different
from instrument lights, but they take a different socket, so use the 
instrument
lights.

The dome light is a problem because the 12 volt bulb is shorter and 
won't fit
the 6 volt light.  The 12 volt dome light, which is readily available 
and cheap,
is larger and won't fit in the 6 volt hole.  I took the brass mounting 
from a 12
volt light and riveted it into the plastic part of my 6 volt light on 
the
non-switch end.  Then the 12 volt bulb would fit.

In my '64 Ghia I pulled out the 6 volt Blaupunkt AM radio thinking I 
could sell
it, and found a sticker on top showing an internal plug that can be 
reversed so
the radio will run on 12 volts.  You have to pull the radio out and 
open the
case.  I was running out of $$ by this point, so I reinstalled the 
radio at 12
volts.  Couldn't justify the AM/FM/cassette now (sigh!  Damn German 
engineers!).
Maybe next year.

On a bus and Ghia you will need a horn relay.  The 12 volt doesn't 
mount the
same as the 6 volt, so I used a plastic cable tie to mount the new 
relay.  The
terminals were numbered the same.  The horn(s) are a straight 
replacement.  Some
people say you can run a 6 volt horn at 12 volts, but mine were shot 
anyway.

The turn signal is different.  The 12 volt has 3 terminals, the 6 volt 
has 2
with the metal case as ground being the third.  A 12 volt wiring 
diagram is
useful here.  The 49 and 49a terminals are straight replacements.  
Connect the
31 terminal to ground. Again, the plastic cable tie makes a good 
mounting
option.  I haven't a clue about making "machts nichtssticks" 
(semaphores) work
at 12 volts.  If you have one of these you probably would be doing a 
restoration
at 6 volts anyway rather than trying to convert as it would be worth 
far more in
original condition.

The wipers are another issue.   You might try running the 6 volt at 
12, then try
to find a motor that fits when your 6 volt burns out.  I bought the 
voltage
changer device, which is no longer just a resistor but a neat little 
electronic
circuit that lowers the voltage and provides you with a speed control. 
 Mounts
in the dash in a 1/4" hole.  Be sure the heat sink fins are clear of 
any wires.
Wipers still run slow, of course, since the motor still sees 6 volts.

The clock can be sent to House of Ghia  in Oregon.  They will 
recondition it and
convert it to 12 volts for $$$.  Even if it isn't working, be sure to 
disconnect
it and tape up the connector.  

I think that's everything.  Allow some time for troubleshooting after 
you get
everything put together.  On an old car there is a lot of corrosion 
and loss of
contact on bulb sockets, so you will have to work at it to get 
everything
working.  Fortunately the older cars have far fewer accessories than 
the newer
ones, like no warning buzzers or lights.

A question is often raised about wiring.  The 6 volt wiring and 
switches work
fine at 12 volts since they carry half the current at the higher 
voltage, so no
changes are necessary.

Parts List:

Generator
Voltage Regulator
Terminals to fit Regulator; Heavy gauge wire.
Generator Stand
Extra Carb. Gaskets (for clearance, if needed)
Shims to match crankshaft
Battery
Ground Cable (if needed).
Starter & Flywheel, clutch, pressure plate (If you decide to change 
them).
Auto choke element or manual choke kit (optional).
Coil
Headlights
Front turn/park lights
Brake and rear turn lights
Taillights
License Plate light(s)
Dome light bulb and 12 volt dome light assembly
8-10 Instrument panel lights
Radio (optional).
Clock (optional).
Horn(s)
Horn relay (Bus & Ghia only).
Turn signal flasher.
Voltage divider or new wiper motor.

Sorry about the line length.  I have trouble moving files from the Mac 
to the editor.

I'm sure there are easier ways to do some of these things, so please 
post or e-mail suggestions.  I'll maintain this file, as this will 
probably come up again.


--Electric Monk            (Bruce Gaede); 
                            e-mail: bjgaed@ccmail.monsanto.com

"...and then time started seriously to pass."
--Douglas Adams, _Dirk Gently's Holistic Detective Agency_