Convert Positive earth to Negative
Paul Rodenhuis
(as many Pommy cars did at the time).
A friend has told me all I have to do is reverse the battery and coil
connections; that's it!! I find this a bit hard to believe as I thought
at least the starter motor and generator would complain.
Can anyone advise on this??
By the way, I think I read somewhere that +ve earth was used as an anti-
corrosion device - is this right??
paulr
--
_____ ___ ___ ___ _____ | Paul Rodenhuis
/____/\ /_ /|/_ /|/_ /| /____/\ | Database Administration
| __ \/| | | || | || | | | __ \/| | Information Services Branch
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| ___/ | |/_| |/_| |/ | |__/ |/ | pa...@pwd.nsw.gov.au (02)-372-7037 B
|_|/ \___________/ |_____/ | VK2AHB@VK2RWI (02)-449-9212 H
Einar Sjaavik
> I have a '57 Ford Zephyr Mk II (English) which has positive earth system
> (as many Pommy cars did at the time).
>
> A friend has told me all I have to do is reverse the battery and coil
> connections; that's it!! I find this a bit hard to believe as I thought
> at least the starter motor and generator would complain.
>
> Can anyone advise on this??
In a '57 Zephyr I assume you do not have an alternator, but a DC generator.
Then it's easy. Take off the generator belt. Reverse the battery poles.
Open the regulator. In your case it should be a relay type. Push down
the armature of the relay for some tens of seconds. When you do that,
the generator will run as a motor. This will repolarize your generator
so it will have the new sense of polarity.
Reinstall the lid of your regulator and your fan belt.
Then "gentlemen start your engines!"
I've done this on all the older English cars/tractors i've had.
I never did anything with the coil connections.
I was told how to do this by an old car electrician. ( He was old 20
years ago, when he told me this )
Some of your instruments may try to go in the wrong direction, and need
to have their terminals swapped.
Check if electric motors will run in the correct direction. If they have
stator windings, they will. If they have permanent magnets, they need a
lead swap. If your heater fan is of the squirrel cage type, it will still
blow (not suck) if it runs backwards, but with loss of efficiency. If
it's the propeller type it will suck ;-)
Your starter have stator windings, and will not need any modification.
That would be difficult anyway, as one pole is the housing.
Beware of the radio if you have one! It may not be enough to swap it's
input leads. Some old radios also need internal mod's.
> By the way, I think I read somewhere that +ve earth was used as an anti-
> corrosion device - is this right??
The only vehicle I have today which have been converted is a '52 Ferguson.
It has not shown any excessive signs of rust 7 years after conversion :-)
Bill Kish
You are correct. Your friend is wrong.
You need to replace your generator, voltage regulator, starter.
Any electric motors (i.e w/s wiper) would run backwards. If you
have a radio, it will need to be replaced.
Unless you have a compelling reason to change over you would probably
be better off leaving it as is!
-BK
fra...@ess2.msfc.nasa.gov
If you are wanting to put in a regular radio, you can
buy a voltage invertor (from -6V to +6v). I bought one
at Radio Shack for $20 before they discontinued them.
I think Whitney's has them.
fra...@ess2.dnet.nasa.gov
"DON'T BLAME ME, I VOTED FOR THE OLD ELVIS STAMP!"
Paul Rodenhuis
Paul Heuer <p...@gwd.dsto.gov.au: wrote:
:pa...@pwd.nsw.gov.au (Paul Rodenhuis) writes:
:
::I have a '57 Ford Zephyr Mk II (English) which has positive earth system
::(as many Pommy cars did at the time).
:
::A friend has told me all I have to do is reverse the battery and coil
::connections; that's it!! I find this a bit hard to believe as I thought
::at least the starter motor and generator would complain.
:
::Can anyone advise on this??
:Subscribe to the british cars mailing list, they are sure to have been
:through this many times. Here's some info:
:
:To be added to the email list send to
:
: british-ca...@autox.team.net
:
:Send your posts for the list to
:
: britis...@autox.team.net
Thanks for this
:
:If the car has a generator and regulator you can just reverse the fields
:(ask an auto electrician how, I'm not sure), watch out for radios - the
:case is often polarised and connected to the chassis of the car.
:As an aside *why* do you want to swap the car over? Is it because of the
:radio (seems a common reason). Why not just insulate the radio from the
:car (don't forget the antenna base) and leave the car as is?
The radio is one reason, and I had worked out that I would have to do
as you suggest. The other reason is for the tacho I bought.
It doesn't work - well it sort of works. At idle, the tacho shows about 600rpm
but as the revs rise, the tacho won't go over about 2 -3 k. As the revs go
higher the reading falls to zero. It will read in the 2 -3 k range with
a light throttle.
I surmise that it has something to do with the polarity of the pulses as it is
a -ve earth tacho. It could also be faulty!
:
:Cheers,
:Paul.
:--
:Paul Heuer | p...@gwd.dsto.gov.au
:Defence Science and Technology Organisation |
:Guided Weapons Division - Avionics Technology | Phone : +61 8 259 6453
:PO Box 1500, Salisbury, South Australia, 5108 | FAX : +61 8 259 5507
--
Einar Sjaavik
> pa...@pwd.nsw.gov.au (Paul Rodenhuis) writes:
>
> >By the way, I think I read somewhere that +ve earth was used as an anti-
> >corrosion device - is this right??
>
> A few years ago I read about a little electronic black box that was
> supposed to stop your car rusting. The basic theory of operation was that
> you connected it between your battery and the chassis and it pumped
> electrons into the metal of the body. They said that rust is caused by iron
> atoms losing electrons to the atmosphere, and this little device was
> supposed to replemish these lost electrons. I suppose that this gave the
> body of the car a NEGATIVE charge, so it seems to me that a positive charge
> earth would do the opposite and accelerate corrosion :)
>
> By the way, this idea isn't as crazy as it may seem - boats have been using
> a similar system for years, but instead of a black box you bolt a piece of
> magnesium (or something like that) to the hull to reduce corrosion.....it's
> been a while since I did 1st year Physics soI can't remember the details
> well :)
For boats old method is to use sacrificial anodes of zink. They will be
corroded first, then the steel. But of course they are replaced before
they are gone. I believe you also will find them as a small fin behind
the propeller of your outboard.
New method is to apply a current to the hull. Then there is an opposite
electrode installed, and the seawater is the electrolyte. This current
have to be exactly controlled, too much can do damage. Today it is easy
( cheap ) to control this, so it is commonly used.
I do'nt believe in this concept working for cars, as air is a known bad
electrolyte, and you do'nt want to immerse your car in water to make
the contraption work.
Justin Zakis
>By the way, I think I read somewhere that +ve earth was used as an anti-
>corrosion device - is this right??
A few years ago I read about a little electronic black box that was
supposed to stop your car rusting. The basic theory of operation was that
you connected it between your battery and the chassis and it pumped
electrons into the metal of the body. They said that rust is caused by iron
atoms losing electrons to the atmosphere, and this little device was
supposed to replemish these lost electrons. I suppose that this gave the
body of the car a NEGATIVE charge, so it seems to me that a positive charge
earth would do the opposite and accelerate corrosion :)
By the way, this idea isn't as crazy as it may seem - boats have been using
a similar system for years, but instead of a black box you bolt a piece of
magnesium (or something like that) to the hull to reduce corrosion.....it's
been a while since I did 1st year Physics soI can't remember the details
well :)
+---------------------------------------------+------------------------------+
| Justin Zakis, Elec. Eng. student, | ~ ~ ~ ~ ~ ~.--- ~ |\~ ~ ~ ~ ~|
| Monash University (Caulfield Campus), |~ ~ ~ ~ ~ ~/ |___| \~ ~ ~ ~ |
| Melbourne, Australia. | ~ ~ ~ ~./ \~ ~ ~ ~|
+---------------------------------------------+~ ~ ~ ~| |~ ~ ~ |
| Email: ski...@yoyo.cc.monash.edu.au | ~ ~ ~ \ | ~ ~ ~|
| jus...@wilma.eng.monash.edu.au |~ ~ ~ ~ \__/~~~~\ / ~ ~ ~ |
| | ~ ~ ~ ~ ~ ~ ~ ~ `-@-' ~ ~ ~ ~|
| | @ = Melbourne~ ~ ~\/ ~ ~ ~ ~ |
+---------------------------------------------+------------------------------+
Paul Heuer
>I have a '57 Ford Zephyr Mk II (English) which has positive earth system
>(as many Pommy cars did at the time).
>A friend has told me all I have to do is reverse the battery and coil
>connections; that's it!! I find this a bit hard to believe as I thought
>at least the starter motor and generator would complain.
>Can anyone advise on this??
Subscribe to the british cars mailing list, they are sure to have been
through this many times. Here's some info:
To be added to the email list send to
Send your posts for the list to
If the car has a generator and regulator you can just reverse the fields
(ask an auto electrician how, I'm not sure), watch out for radios - the
case is often polarised and connected to the chassis of the car.
As an aside *why* do you want to swap the car over? Is it because of the
radio (seems a common reason). Why not just insulate the radio from the
car (don't forget the antenna base) and leave the car as is?
Cheers,
Luke Plaizier
> You are correct. Your friend is wrong.
> You need to replace your generator, voltage regulator, starter.
> Any electric motors (i.e w/s wiper) would run backwards. If you
> have a radio, it will need to be replaced.
You shouldn't NEED to replace the alternator, it's just a matter
of working out a terminal swap (A twelve volt alternator is a twelve
volt alternator, whether it has positive or negative earthing.)
I think you'll find the wiper problem is unfounded. Only on very few
cars are the stator/coil windings static. In fact it is a problem I
have encountered previously. I have only found the Peugo wiper motors
are reversible. Starter Motor needs a polarity swap agreed. I must
emphasize that I have not done this sort of thing before and am only
talking from past experience and common senseights should work no
matter the polarity.
> Unless you have a compelling reason to change over you would probably
> be better off leaving it as is!
Here Here!
> -BK
Richard Neill Dabney
>Path: mack.einet.com!lynx.unm.edu!umn.edu!news-feed-2.peachnet.edu!gatech!howland.reston.ans.net!pipex!sunic!trane.uninett.no!news.eunet.no!nuug!ade!einar
>From: ei...@ade.no (Einar Sjaavik)
>Newsgroups: rec.autos.antique,aus.cars
>Subject: Re: Convert Positive earth to Negative
>Message-ID: <s4T8gc...@ade.no>
>Date: Fri, 04 Feb 94 10:12:39 CET
>References: <rdabney.6...@einet.com>
>Organization: AD Elektronikk AS, Norway
>Lines: 19
>> > You need to replace your generator, voltage regulator, starter.
>> > Any electric motors (i.e w/s wiper) would run backwards.
>>
>> My wipers in my '63 Midget go right-to-left. Are they supposed to go
>> left-to-right? ;-)
>On a British car, they are.
>Driver sits on the passenger side in Britain, so thats the way they like
>them to go.
The driver sits on the passenger side? Those crazy Brits!! It must get
uncomfortable reaching over from the left seat. Why don't they sit in the
drivers seat?
>I really dont think you will be bothered by that. But you may be bothered
>by the wipers motors losing current *after* bottom dead point when you
>turn them off. That will make them run back up a bit before halting.
The Midget above is converted to negative ground and does not exhibit this
phenomena. I've never seen a Britich car that has. There is so much friction
in a wiper system that as soon as the motor is shut off it stops.
>This will happen only if you have permanent magnet wiper motors (that will
>run backwards ).
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Richard Neill Dabney
microSciences
Albuquerque, New Mexico
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Richard Porter
Luke Plaizier <luk...@scorch.hna.com.au> wrote:
>ki...@watson.ibm.com (Bill Kish) writes:
>
>> You need to replace your generator, voltage regulator, starter.
>> Any electric motors (i.e w/s wiper) would run backwards. If you
>> have a radio, it will need to be replaced.
>
> You shouldn't NEED to replace the alternator, it's just a matter
>of working out a terminal swap (A twelve volt alternator is a twelve
>volt alternator, whether it has positive or negative earthing.)
Might depend on the alternator, but mine has the negative connection
via the casing. Also it has an integral rectifier and regulator pack
which are not reversible. However, if there's a separate voltage regulator
the chances are that the generator is a dynamo, not an alternator.
>Starter Motor needs a polarity swap agreed.
No. I used a starter motor off a pos. earth car as an emergency replacement.
It worked fine, though with a bit less power probably due to the residual
magnetism. Perhaps flashing the fields would be a good idea. I've never
tried it.
>> Unless you have a compelling reason to change over you would probably
>> be better off leaving it as is!
From my point of view, there are some neg. earth items on the car already,
and I want to convert to alternator charging and possibly fit a Lumenition
unit, so conversion to negative earth is essential.
I mentioned that the radio could be wrongly polarised as long as the case
is isolated from the chassis. I should have pointed out that you have to
be careful not to earth the case via the aerial cable. This can be achieved
by severing the screen near the radio and inserting a small capacitor.
Richard
Jody Levine
>Driver sits on the passenger side in Britain
Must be hard to reach the pedals!
Sorry, I had to,
Jody
Jody.P...@hydro.on.ca - Toronto, Canada - "Fuddle Duddle"