North American Turbocoupe Organization



3G Alternator Install
andrewjs18 Offline
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Installing a 130 Amp Alternator in your Turbo Coupe
By Jeff Korn

All Turbo Coupes came with either a 65 Amp of 75 Amp alternator from the factory.  While somewhat adequate for 83 to 86 model years that have one engine cooling fan, and no other added electrical accessories, such as a high powered stereo, these low power alternators , in my opinion, do not put out enough power for 87-88 cars that have higher electrical demand due to their two engine cooling fans, programmed ride control, and antilock brakes.  I have heard of high failure rates of stock alternators in 87 - 88 cars, and I believe this is due to the high power demand placed on the alternator, forcing it to run at a large fraction of its rated output much of the time, which will shorten its life. A solution to this problem is to upgrade to a Ford 3G (third generation) 130 Amp alternator, which will provide more than enough power to handle any electrical load.  This upgrade is very common in the 5.0 Mustang world, and while installation on a Turbo Coupe is slightly more involved, it is still pretty much of a straight forward swap. I did this swap several years ago on my 86 Thunderbird 5.0, and have been very pleased with the results, so I bolted one up to my 88 Turbo Coupe to enjoy the same freedom from inadequate charging power.    

   

picture courtesy of Jeff Korn

PARTS AND TOOLS NEEDED:

A 130 Amp 3G alternator.  These are available from many sources. I got a new one from PA Performance (www.pa-performance.com). I purchased their alternator upgrade kit for 87 to 93 Mustangs for $189, which includes a new stator plug, and upper mounting bolt.  These alternators  can be found at the local parts store for about $200 (ask for an alternator for a 94 Cobra), or the junk yard.  My personal feeling with parts such as alternators is to pay the money for a new part, versus getting one from the junk yard for $50 that already has had 100,000 miles of use. The PA performance alternator comes with a threaded upper mounting hole and a bolt.

The 3G alternators from the parts store or the junk yard do not have a threaded upper mounting hole, so if you get one of these, you will need a 1/4" bolt about 3 inches long, and a nut. If you go the junk yard route, be aware that not all 3G alternators, which can be recognized by their dual internal fan design, Aswiss [email protected] front cover plate, and stud terminal output, are not all rated at 130 Amp output.  Some are rated at 90 or 95 amps, and may be as low as 75 Amp.  The alternator in my 91 Escort has the typical 3G design, but has a smaller case, and is only rated at 75 Amps. All 130 Amp versions I have seen say “130 Amp” on a stick on tag located on the case, and the voltage regulator says “heavy duty”.

A stator plug, which is a small single terminal plug unique to the 3G series of alternators. This is included in the PA Performance upgrade kit, or can be obtained from Ford for a few dollars, or free from the junk yard (grab one and put it in your pocket).  If you have an 83 –86 with an externally regulated alternator, you will also need a new voltage regulator three terminal “D” shaped plug. They are available from PA performance, Ford, or the junk yard.  My regulator plug was in pretty sad shape, so I replaced it with a new one.  

About 6 feet of 10 gauge wire and four 10 gauge compatible ring terminals.  

Some kind of grinder to modify the lower alternator mounting bracket.

A soldering gun and electrical solder.  A pencil type soldering iron will not work. A soldering gun rated at least 140 Watts is needed to solder the heavy gauge wires involved.  Half way decent soldering skills are also a requirement.  

Typical hand tools / supplies- wrenches, sockets, electrical tape, wire cutters and strippers, single edge razor blades, etc.

A voltmeter to check your work.


THE SWAP - OUT WITH THE OLD

Disconnect the positive battery terminal.  (Personally, I never do this, but then I have 30+ years dealing with electronics, and feel safe leaving the battery connected, but I urge most to disconnect it.) Remove the alternator drive belt. Undo all the electrical connections to the alternator and voltage regulator.  This depends somewhat on what year your car is.  For 87-88, remove the regulator plug and heavy gauge power output lead from the stud on the back of the alternator.  For 83-86 externally regulated cars, remove the wiring from both the regulator and alternator. The external regulator will not be reused.

Unbolt the alternator upper and lower mounting bolts, and remove the alternator.  On my 88, the lower mounting bolt wouldn’t come out all the way without hitting the coolant overflow tank, but it came out far enough to get the alternator out.

Now is a good time to compare the pulley diameters on both the old and new alternators. If they are much different, reuse the original pulley. The pulley on my new 3G was virtually the same diameter as the original.

The 3G alternator has a larger case than the OEM alternator, so some trimming of the lower alternator / power steering bracket is necessary.  Refer to the “ before and after” figures to get a feel how much material must be removed from the bracket.  

       

above pictures courtesy of "Joe Frazier"

I covered the rest of the engine with an old sheet so as not to get metal filings all over everything while grinding.  The [email protected] bracket looks like a real hatchet job, but this area will be fully hidden by the new alternator. This bracket is quite massive, so I do not think the amount of metal removed will compromise its strength. To determine exactly how much to trim from the bracket, I put the new 3G alternator  in using the lower mounting bolt, and use a strip of paper between the alternator case and bracket to see where material needed to be removed from the bracket. I continued to remove material from the bracket until the upper mounting holes lined up.  It took me about 20 minutes with the air powered cut off wheel / grinder shown in the figure to trim the bracket.

   

picture courtesy of Jeff Korn

IN WITH THE NEW

Once the bracket trimming is complete, install the new alternator using the original lower mounting bolt, and either a new nut and bolt, or just the new bolt included in the PA Performance upgrade kit to attach the alternator to the upper mounting bracket.  Note that the regulator input and stator input point straight down.  You can still get the plugs on, and it actually leads to a cleaner look with them pointing down.  It is not recommended that you try to “reclock” the alternator to reposition the terminals.

Now for the electrical wiring. This will depend on which alternator you just removed – internally or externally regulated.  The only difference between the two is wiring the regulator.  The power output wiring is the same for both.

   

Internally regulated (87-88).  Look at the regulator socket on the 3G alternator. The terminals will be marked I, A, and S.  Now, look at the three terminal regulator plug. There will be a light green /red wire, a yellow / white wire, and a black /white or all black wire.  As far as I know, these color codes remained constant over the years.  Temporarily reconnect the battery, and measure the voltage on the yellow / white wire, which should be 12 V. This is the voltage sense wire, and needs to be connected to the A terminal on the regulator (through the regulator plug, of course).  The light green / red wire should have 12 Volts present when the key is in the run position only.  The voltage on this wire tells the regulator the car is running, and needs to be connected to the I terminal on the regulator.  The black  or black / white wire needs to be connected to the S terminal on the regulator, and to the stator terminal next to the regulator connector using the stator plug you obtained earlier. Figure four shows the wiring for the 3G alternator.  Disconnect the battery again after you have confirmed the voltages on these wires.  Be sure to solder and tape up all connections!  Note that on my 88, the regulator plug had all these wires, but in the incorrect order, which required some cutting and splicing. Also, on my 88, the black wire just went into the harness, and ended – it was not connected to anything.

Externally regulated (83-86). Be sure you have a three terminal D shaped regulator plug before you begin. Look at the regulator socket on the 3G alternator. The terminals will be marked I, A, and S.  Now, look at the wires going to your external regulator. There will be a light green /red wire, a yellow / white wire, and a orange/light blue wire.  As far as I know, these color codes remained constant over the years.  Temporarily reconnect the battery, and measure the voltage on the yellow / white wire, which should be 12 V. This is the voltage sense wire, and needs to be connected to the A terminal on the 3G internal regulator (through the regulator plug, of course).  The light green / red wire should have 12 Volts present when the key is in the run position only.  The voltage on this wire tells the regulator the car is running, and needs to be connected to the I terminal on the 3G internal regulator.  Disconnect the battery again after you have confirmed the voltages on these wires.  The black  or black / white wire which is connected to the S terminal on the regulator via the regulator plug, needs to be connected to the stator terminal next to the regulator connector using the stator plug you obtained earlier.  The orange/light blue wire between the external regulator and the original alternator is not used. Figure four shows the wiring for the 3G alternator.  Be sure to solder and tape up all connections!  The original external voltage regulator can be removed.

Connecting the alternator output.  On a 5.0, this is easy… just run a 4 or 6 gauge wire from the output stud on the alternator to the battery terminal on the starter solenoid.  Unfortunately, due to wiring differences between our cars and 5.0s, which is mainly due to the amp gauge on our cars, this is a somewhat more involved process.  I am sure there are other ways to do this, but using my method does not overload any of the smaller power feed wires, and pretty much preserves the operation of the amp gauge.

Cut two sections of 10 gauge wire about a foot long, and a third section about two feet long.  Put ring terminals on one end of each, and secure to the alternator output stud.  Do not over tighten this connection.  Put another ring terminal on the other end of the longer 10 gauge wire, and attach this wire to the battery stud on the starter solenoid.  Be sure to solder, as well as crimp the wires to the ring terminals.

Now comes the fun part.  Locate the huge taped bundle of wires mid way between the alternator and the starter solenoid.  This is the main wiring junction. The original output wire from the original alternator goes into this bundle.   Use a knife, razor blade, etc. to cut the tape off the bundle. Inside you will find a thick yellow wire with a huge splice into several fuse links at each end.  The yellow wire is the shunt wire for the amp gauge.  Follow the original alternator power output wire to the splice at one end of the yellow wire.  Cut the original power wire a few inches from the huge splice, and connect it to one of the two remaining 10 gauge wires from the alternator.  Be sure to fully solder and tape this connection.  Use a knife or razor blade to remove about ¾” length of insulation from the thick yellow wire near the same end that the alternator power wire is spliced in to.  Strip some insulation from the last 10 gauge wire coming from the alternator, wind it around the bare section of the yellow wire, solder completely, and tape the connection up.  Push the wires all back together, and retape the whole bundle up so it looks more or less like it did. A tie wrap around the whole mess of wires will help hold them together before you tape them up.  Next, tape wrap the bundle of three 10 gauge wires with a good layer of tape, and enclose in split loom to eliminate any possibility of the wires chaffing. Note this is shown in figure five also.  Plug the regulator and stator plugs into the new alternator from the bottom.  Last, securely reconnect the positive battery cable. You are done!  Note that if you try to skimp, and just run ONLY the original power wire only to the new alternator, you WILL overheat the wire, and possibly start a fire due to the high current output of the alternator!

TESTING

Attach a voltmeter across the battery. It should read around 12.5 V or so. Start the car.  The voltage should quickly increase to 13.9 to 14.4 V, depending on the regulators temperature.  In cold conditions, the regulator increases charging voltage. Turn on the headlights and heater blower to high. Battery voltage should only drop a few tenths of a volt, if at all.

Now you can add just about any electrical accessory to your car you want without fear of overtaxing the alternator.  No longer will your lights dim at idle, and as a side benefit, you can expect longer alternator and battery life.

View of the complete installation:

   
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