Upgrading an Oliver Super 55 Electrical System
by Dennis Hawkins
My old Oliver Super 55 has been just sitting and rusting for several years
now. I really hate to see a good tractor being treated that way, but not
being able to start it without a 30 minute point filing ritual every time
contributed to its demise. If it would just start when I turn the key, then
I would use it more often. In addition to a bad case of old age, most of
the tractor's original electrical system was simply too unreliable to keep.
The main focus of this page is to show how I upgraded my Super 55's electrical
system to a modern, more reliable one. There are three main electrical subsystems
on the Super 55. These are the Starter circuit, the
Generator circuit, and the
Ignition System. There are other things such as fender
lights and gauge lights, but I won't be getting into those here. One of the
main things that I wanted to do was to convert the tractor from the old fashioned
6 volt, positive ground system to a 12 volt negative ground system. Virtually
every kind of automotive electrical device built these days is made for a
negative ground electrical system.
Now you recall that I just said that I wanted to convert from a positive
ground to a negative ground system. With some electric motors, and starters
are electric motors, they will spin backwards if you connect the electricity
to them backwards. If a starter motor started spinning backwards, it's bendix
gear would not be able to engage the flywheel because of the way that it
is designed. Even if it did, the engine could not possibly start running
Fortunately, the reverse running trait is only associated with permanent
magnet motors. These are the kind of electric motors that have strong magnets
instead of a field winding. While starter motors that have permanent magnet
fields can run backwards, all starter motors that use a field winding will
always run in the correct direction regardless of electrical polarity. While
you will see permanent magnet starter motors every now and then, I can say
with certainty that there were none ever installed on an Oliver Super 55.
Therefore, there is no need to be concerned about the starter rotation when
switching the ground polarity.
So now that I have connected the 12 volt battery up to the 6 volt starter
backward, will it burn the motor out? The answer is no. If we were talking
about light bulbs (If your tractor still has them you should pay attention
here) putting 12 volts to a 6 volt bulb would, to say the least, shorten
its life tremendously. However, starter motors are different. They only run
for brief periods of time. Applying double the voltage for the short duration
that it takes to start an engine will not harm a starter motor.
Well the starter part of the conversion was pretty easy. I hope you didn't
work up too much of a sweat. However, since you are thinking starter
right now, this might be a good time to mention that replacement brush assemblies
for Oliver starters are still being made because they also fit some cars
starters as well. If you are having any trouble with your starter, a new
pair of brushes might be just the ticket.
While the starter will work correctly for either positive or negative ground
systems, the generator is not so simple. The old Oliver generator was designed
for a positive, not negative, ground system. Coupled with the fact that it
was designed to charge a 6 volt battery and not a 12 volt battery, I decided
that it was time to make the leap to an alternator system. Although the old
6 volt positive ground generators can be repolarized so that they work on
a negative ground system, you still won't get enough voltage to charge a
12 volt battery. Even if you did, there is still the reliability factor.
The first thing to do when replacing a generator with an alternator is to
select a replacement alternator. I chose a GM 10 SI alternator because it
is cheap and has a built-in electronic regulator. It comes in a variety
of amperages, but if you get one, I suggest you ask your automotive store
for an alternator matching part number 7127. Sometimes different manufacturers
will add an extra digit or a letter, but "7127" will usually be in there
somewhere. If the kid behind the parts counter can't handle that, just tell
him you need one for a 1978 Chevy truck. At first you might be tempted to
visit a junkyard for the alternator, but considering a remanfactured one
typically retails for around $35, it really isn't worth it.
The New Alternator Bracket
The most difficult part of installing an alternator on the Super 55 is making
a bracket with which to attach it to the proper place. While it is possible
to attach the alternator with only a shoulder bolt and a handful of washers,
using a solid bracket is the best method and is discussed in detail here.
The old generator was mounted with bolts at both ends plus the belt tensioning
bolt - three bolts total. The 10 SI is made to use only one long bolt plus
the tensioner. This means that the rear bracket won't be used when installing
the alternator. The front bracket is a different story. If you want the
alternator mounted in a solid way, it will be necessary to fabricate a suitable
replacement bracket as the old one will not work. If you aren't familiar
with using a grinder and drill, it is a good idea to practice on a few test
pieces before going all the way. It also helps if you have friends that already
know how to fabricate metal brackets.
make the new bracket, you need to find a large enough piece of stock metal
about 1/4 to 3/8 inch thick. Next, trace the footprint of the old front bracket
onto it including the two mounting holes. Draw an additional 3/8" hole about
an inch over the upper hole by extending the height of the bracket drawing.
This extra hole will be used to mount the alternator. Now drill the smaller
holes making sure that you get them in the same position as the original
bracket. Then drill the larger 3/8" hole. Using a grinder with a cutoff wheel,
shape the stock metal to match the pattern you have drawn. Make sure that
each hole has at least 1/4" of metal around all sides - anything less will
be too unstable. This photo shows what your new bracket should look
To finish the
bracket, you will need to weld a 3/8" nut to the rear of the 3/8" hole. To
do this, get a long, scrap 3/8" bolt and thread a scrap nut onto it about
an inch down from the end. Put the end of the bolt through the front of the
bracket and screw on the nut that you will be welding to the rear of the
bracket. When this is tight, you can use the bolt to hold the piece and weld
it easily. You should not attempt to weld a nut without having a bolt threaded
through it. If you do, the nut will warp and you won't be able to get the
mounting bolt through it. In fact, don't remove the bolt until the bracket
has cooled. When welding, it is important not to use too much heat or else
you might weld the scrap bolt and nut together!
Once you have made the bracket, simply bolt it on where the old bracket was.
The bottom of the alternator attaches to the bracket with a long 3/8" bolt
and about a dozen spacer washers as shown in this photo. Make sure that the
alternator pulley lines up with the crankshaft pulley. You can use the same
tensioner bolt and tensioner bracket on top that the old generator used.
Lastly, install the belt (preferably a new one) and tighten it with the
alternator tensioner bolt. The mechanical portion of the alternator installation
is now complete.
Wiring the New Alternator
old generator wiring cannot be used for the alternator. The best thing to
do is remove and replace it with a new one. These can be purchased
for about $20.
They come with all the necessary connectors, wires, and diodes. With my tractor,
I also went the extra mile and purchased a new pair of heavy duty battery
cables, and a dash gauge set from a local automotive store. The gauge set
was kind of expensive at $50, but it included new gauges for oil pressure,
amps, and water temperature. With those installed, the new wiring harness
attaches to the ampmeter and the ignition switch. The exact wiring instructions
are included with the new wiring harness.
The alternator conversion and installation is now complete. Unlike the starter,
which didn't really require anything, the alternator conversion does take
a little bit of effort.
The Ignition System
As I stated at the beginning of this page, the main reason for allowing the
old Oliver to sit and rust was because of having to file the points every
time I wanted to start it. The points will oxidize and fail if the engine
isn't run periodically. Consequently, I didn't try very often. This made
things even worse. What I needed was an electronic ignition module to replace
the old points.
I was quite surprised to find that there was so much support for Oliver tractors
on the Internet - particularly at the
Yesterday's Tractors web
page. I found a few Electronic Ignition module companies, but they required
that the distributor be permanently altered (by cutting) in order to make
it fit. I was opposed to this because I wanted to be able to put everything
back the way it was in the event that it didn't work as promised. Also, I
would advise everyone reading this to steer clear of "point amplifiers".
These are boxes that mount on the outside of the distributor and allegedly
preserve the points by reducing the current that flows through them. Essentially,
they are electronic ignition units that use the points themselves as the
pickup mechanism. They are worthless as far as tractors are concerned. If
you purchase an Electronic Ignition unit, make sure that it uses a magnetic
Finally, I found a good one. Before I bought
it, I told the technician that I didn't want to
start the installation process if it was going to require any welding, sawing,
or special tools. He assured me that I could complete the installation with
nothing more than a screwdriver and a pair of pliers. I bought one, and he
was right. Their modules look essentially like a big aluminum washer with
a plastic blob on it with wires sticking out of it that gets installed inside
the distributor in place of the points and condenser. It seemed kind of small,
but after installing it, the tractor started right away - even after sitting
for 3 years. In fact, I photographed the entire installation process so that
others can see how easy it is.
is a photo of the tractor's electrical parts before the installation of the
electronic ignition unit has begun. The tractor has been in the family since
the early 1970's. Before that, it belonged to someone who liked little red
tractors. The tractor looks a little strange now that half of the cheap red
paint has flaked off to reveal the Oliver green underneath. On the right
of the photo, you can see the alternator that I have also begun to install.
At the time that this photo was taken, I was in the middle of the alternator
this photo, you can see a close-up of the original distributor cap and coil.
Although not shown in this photo, I have already replaced the spark plugs
with new ones prior to beginning the installation process. The old ones were
badly corroded from moisture and non-use.
installation process begins by removing the distributor cap and dust plate
to reveal the original points and condenser.
In order to install the electronic ignition kit, you have to
remove the old points and condenser and the plastic insulator post that connect
them. With a screwdriver, I removed the points and condenser in the usual
way. I had to use the pliers to get the post out. The important thing to
remember is that the original equipment has not been damaged and could be
reinstalled if necessary.
Now I have installed the electronic ignition module "washer" using the same
screw that used to hold the points in place. I also put the screw that held
the condenser back in even though it really doesn't hold anything. Around
the center shaft is a molded plastic magnetic inducer. This piece of plastic
actually has four magnets in it that are precisely aligned to fit my distributor
in this new configuration. The form fitting plastic makes it difficult to
install incorrectly. Note that you have to feed the two wires through the
hole where the insulator post used to be and install a rubber strain relief
Once the electronic ignition module was installed in the distributor, it
was just a simple matter of reinstalling the new cap, rotor and dust plate.
The hard part was over.
In this photo,
I have replaced the old 6 volt coil with a brand new 12 volt coil that has
an internal resistor. The connections are pretty simple. The red wire goes
to the positive side of the coil. The black one goes to the negative side.
The positive side of the coil also goes to the ignition switch. The old coil
was for a positive ground and had the negative side going to the ignition
switch, but since everything is negative ground now, we have to do it this
Lastly, I have installed a new set of spark plug wires. When
I cranked the tractor for the first time after installation, it started right
up. It spit a bunch of rust out of the exhaust pipe which I assume was from
sitting for so long.
One thing about the wiring harness is that there is room to slide
the old ignition wire in there. There is a slit that runs the length of the
harness. This photo shows how I slipped the old coil wire in with the alternator
wires. This is totally unnecessary, but it gives the tractor wiring a cleaner
MAKE SURE YOU CONNECT THE NEGATIVE TERMINAL OF THE BATTERY TO THE
CABLE THAT CONNECTS TO THE FRAME!
Your tractor's new electronic parts can be harmed if you connect the battery
the old positive ground way!
The fixing up process is far from over, but at least now I have something
that will start when I crank it and recharge the battery while running. The
new alternator electronic ignition unit greatly increase the reliability
of the tractor to the point where it can be used more often. Just letting
it sit is probably the worst thing that you can do to a tractor. Hopefully,
those days are over.
Article Copyright 1998 by Dennis Hawkins - All Rights
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