The Adventures of a Cadillac Alternator (long!)

[Travis Goodwin <tgoodwin@xxxx>]

[First off, let me say that I can't be held resonsible if you hurt yourself
or cuse your car to trvel in tim unexpectedly by doing what I'm about to
detail. This will be my first white paper on the Cadillac Alternator. Most
documentation on the web I found helpful, but ultimately I thought I would
document my own experiences to help anyone else who might want to try this.]

First off, my car had the original Ducy alternator and had burned through 2
batteries before I wised up. I investigated the Motorola and other
replacements from PJ Grady but decided to do it the hard (and less
expensive) way.

All of the parts that I used are available at Advance Auto. Here they are:

P7157 100 Amp Alternator from a 1980 Cadillac Deville - $69 with $30 core
DAYCO 15515 Alternator Belt - $14
Mr Gasket Co. alternator adjustment arm #9851 - $13
Calterm GM alternator plug #08602 - $3
A pack of male terminal ends - $1

I won't detail the removal of the old alternator... needless to say, just
yank that sucker outta there. Before you do, make sure you've disconnected
your battery, otherwise you'll find out why cattle prods are so effective.
Remove the adjustment arm bracket as well and save it for reference. 

Take the new GM alternator plug and attach a terminal end to the red (field)
wire. The white wire isn't used, at least not in a my Ducy setup (I think
the Motorola's use it, but I don't know for sure). Attach the plug to the
alernator's terminal and snap it down. Bolt the alternator to the mounting
bracket and let it hang loose. It is a direct fit into the mounting bracket.


One thing you will notice is that it is much larger than the original and a
straight adjustment bracket won't work for it. It has to be curved. I made a
cardboard cutout of a bracket that had the approximate dimensions and the
correct curvature to it. I took it to a junkyard and found some that were
close (1982 Datsun, 196? Thunderbird) but I wasn't pleased with them so I
decided to make my own. You'll notice the #9851 adjustment bracket is VERY
long and flat. Fret not. Simply cut off the first 3 inches of the straight
end (with the 2 bolt holes) and drill a new one on that same end about an
inch from the end. Grind off the sharp edges and and smooth out the end so
you don't cut yourself on the installation. Now, here comes the fun part!
You'll notice your original bracket has a 1 inch offset. The offset puts the
bracket one inch away from the engine (towards the muffler) and attaches at
the front of the alternator beneath the fan. I chose to bend it the other
way (towards the engine) and mount it on the back of the alternator so it
would not interfere with the fan.

Using a strong vice, slide the newly created end in about 3 inches. The
curve of the top of the bracket should go to your right to mount at the way
I did it or to the left to mount the way the original bracket mounted
(undereath the fan). Keeping it perpindicular with the top of the vice (you
can protect it from the teeth of the vice with a rag) put a 45 degree bend
in it by pulling the bracket towards you. Don't be afraid to put your ass
into it, you'll need to. The metal bends smoothly, but it will take some
effort. Hammering won't work on this since it requires a constant force to
make the bend. Reposition it in the vice 1 1/2 to 2 inches farther down and
pull it towards you until the end you have in your hand is parallel to the
end that is below the vice's clamp. REMEMBER! After each of the prior steps,
check with your original bracket to make sure your angles are correct. After
a few adjustments, yours should be good.

You'll notice that the alternator adjustment bolt is too big to fit into the
slider part of the arm. Simply take a bastard file or a rasp and file the
hole length wise on the top and bottom until the bolt slides easily across
its length. The metal is soft and it shouldn't take too much effort.

The rest is simple, attach your new arm to the engine and bolt it to the
alternator. If you bent it in reverse away from the fan, the bolt will screw
easily into the back as it does in the front. Attach your belt and tension
it. Reattach your battery leads and plug in your field wire (solder or tape
to secure it). I snipped off the leftover white wire since it wasn't used in
my application. Reattach your battery and crank her up. All done. Now don't
you feel like you've accomplished something?

You'll notice that the creating of the adjustment bracket is the largest
step. I did a lot of hunting in the junkyard and spent basically a week
looking for the best option. Other options may be available to you depending
on what your local auto supply shops stock. If you are not comfortable with
the way I did it, create a template out of cardboard and see what you can
find that might be a better fit. Unfortunately, I haven't heard of anyone
getting a direct replacement without having to modify it somewhat. 

I'm working on getting some pictures and converting this document into a PDF
for the Files section. Give me your feedback so I can include it before the
final version.

Enjoy!

Travis
#3512 (with a shiny new "cop car" alternator)