Chuck,
I have converted several cars from positive ground to negative ground. The
advantages are if you want to install a radio (much easier than trying to
isolate the radio chassis from the car chassis) or you want to install an
electronic ignition. If you don't intend to do any of these things, I would
recommend leaving it positive ground.
To convert to negative ground you need to do two things. The first is to
re-polarize the magnetic field in you generator and the second is to reverse
the wires on your ammeter. So start out by disconnecting both connectors to
your battery. Then remove the connections to your generator. Take a set of
jumper cables and connect the negative to the body of your generator and
take the positive cable and momentarily touch the field connector on the
generator (that is the smaller connector). You should see a little spark.
Make sure that you only touch it for just one second. What you are doing is
re-polarizing the magnetic fields in the generator. If you don't do this
step and just hook everything up for negative ground, you will get a very
large current spike when you first turn the ignition on that could damage
some wiring. Once you have re-polarized the generator you will no longer get
this current spike. This is good practice to do anytime you replace a
generator since you never know how it was last polarized.
The next step is to get under that dash and reverse the wires to the
ammeter. You need to do this so it will continue to read + when charging and
- when discharging the battery. After completing this, reconnect the battery
cables, negative to the car chassis and positive to the main cable. I find
you usually will want to change the connectors, at least for the main cable
since it previous went on the smaller terminal post (negative) and now must
fit on the larger post (positive). Once these cables are hooked up you are
all done. You do not need to reverse any other connections since all your
electric motors (fan, heater, starter) will still turn in the proper
direction. By the way if you ever need to reverse the direction of a DC
motor you need to reverse only the field or the brush winding, but not both.
So good luck if you decide to make the change.
Phil Roettjer
67 Morgan +4
67 MGB
80 Porsche 928
> -----Original Message-----
> From: Vandergraaf, Chuck [SMTP:vandergraaft@aecl.ca]
> Sent: Tuesday, May 04, 1999 9:58 AM
> To: 'DGreimel@aol.com'
> Cc: morgans@autox.team.net
> Subject: RE: Cleaning cream switches and Indicator switch
>
> Don,
>
> Thanks for this information; it is very helpful to those of us who are
> contemplating switching over to negative ground (or earth). I have four
> questions:
>
> 1. if the only vulnerable part is the voltage regulator (my '52 does not
> have a radio), can I substitute a proper voltage regulator, i.e., one
> designed for negative ground?
> 2. I've heard that one of the reasons for accelerated rusting of LBCs is
> that they came with positive ground. Is there any truth to this rumour?
> I
> somehow doubt it, considering the number of rusted Hyundais, Toyotae and
> Hondae I have seen.
> 3. what is the advantage to switching over to negative ground?
> 4. isn't the engine already grounded through the bolts that hold the
> engine
> to the frame or is the resistance through the bolts too high?
>
> Thanks again.
>
> Chuck Vandergraaf
> '52 +4
> Pinawa, MB
>
>
> > ----------
> > From: DGreimel@aol.com[SMTP:DGreimel@aol.com]
> > Reply To: DGreimel@aol.com
> > Sent: Tuesday, May 04, 1999 4:52 AM
> > To: morgans@autox.team.net
> > Subject: Re: Cleaning cream switches and Indicator switch
> >
> > Ben:
> > Your Morgan was never a 6 volt car. The British stuff has all been 12v
> > Positive Earth since the beginning of time. Your Mog had two 6 volt
> > batteries
> > wired in series. Installing the battery with Neg earth will cause only
> > two
> > problems. It will shorten the life of your voltage regulator due to its
> > use
> > of different metals on the contacts which is designed to reduce metal
> > transfer and it will waste your transistor radio. Otherwise the
> > everything
> > would function normally. The most likely cause of your hot cable is
> that
> > the
> > battery is grounded to the frame and there is no ground strap between
> the
> > frame and the engine, which of course is sitting on rubber mounts.
> > I once say a Morgan in which the choke cable turned red hot while
> > cranking.
> > The owner had replaced the battery, generator and starter in his attempt
> > to
> > cure the slow cranking problem. A ground strap across an engine mount
> > fixed
> > it for $.50.
> > Happy Moggin.
> > Don Greimel
> >
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