How-To: Upgrading 89-93 MTX alternator to 94-95 MTX alternator

Discussion in 'Gen 1 & 2 - Guides (For How-to guides, NOT how-to ' started by element913, Jul 22, 2005.

  1. element913

    element913 SHO Owner Elite

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    Hey all,

    This is the first how-to I have written, so bear with me here.

    What you need (mandatory):
    (1) 94 or 95 Ford 3G Alternator (obviously)
    (1) 94 or 95 accessory bracket (engine mount bolts to this, as well as alt and ac compressor)
    (1) Alternator bracket (this sits bolted to the forward, towards the front of the car, side of the ac compressor and holds the alternator)
    (1) Harness kit for a Ford 3G alternator, I used this one from PAPerformance http://www.pa-performance.com/display.asp?sku=27&rP=searching,cat@Plugs+and+Wire+Kits,cR@categories.
    (1) 18 gauge fusible link (I got mine at a local napa auto parts)

    Required but varying by application:
    Depending on how much amperage your alternator is putting out you will need a corresponding wire size. I had my alternator rebuilt at a local alternator shop, Pacific Auto Electric in Sunnyvale, CA (great work, they made my gen2 starter too) to 185 amps and as such I run a 2 gauge wire from my alternator to a 200 amp circuit breaker.

    How-to install/retrofit:

    (1) Remove the battery (this part is pretty straightforward).
    (2) Remove the coolant resivoir (there are two 8mm bolts holding this, you may have to remove your radiator cover first, which also uses 4 8mm bolts)
    (3) Put the car on jackstands.
    (4) Remove the passenger wheel.
    (5) Remove passenger side wheel well.
    (6) Hoist the engine, at least enough to pull the load off the engine mount in the front, DO NOT hoist it by the front engine lifting eye (the thing behind the alternator) as you WILL be removing that. (If you do not have a hoist, you can also use a piece of wood and a jack under the oil pan to push the engine up)
    (7) Loosen the 14mm idler pulley nut for the AC/Alt belt, and rotate the allen headed bolt (5mm size) to loosen the belt, remove the belt.
    (8) Remove the alternator, 3 bolts (I cant remember the sizes, and also take off the connectors)
    (9) remove the AC Compressor (4 bolts, I believe they are 13mm)
    (10) Remove lower front engine mount bolts.
    (11) Remove the Accessory bracket (4 bolts, I belive they are 14mm), this will take a little hammering, there are alignment pins (much like the dowel pins in a pressure plate) that keep the bracket inline with its mounting points.

    The rest is basically a reverse of this but with the 94-95 Alternator Parts. The AC Compressor is the same for all years and WILL bolt up fine to the new bracketry from the 94-95. I had to trim the bolt going into the bracket at the rear of the alternator about 3/8" so that it wouldnt hit the front head, and I was not able to use the lifting eye with this bracket.

    Another important thing to note is that I had to make a spacer (out of thin pipe) to push the oil dipstick forward about an inch (to clear the new alternator B+ terminal)

    Now for the wiring:
    The wiring is pretty simple (This is for my 89 sho, 90-93 may be different, refer to wiring diagrams and verify all colors before attempting any modification of your wiring harness).

    Installing the 3g connector:
    How I did it was cut off the old alternator 2 pin connector and connect the 3G upgrade harness from PAperformance, connect the yellow and green/red wires accordingly, The white and black wire on the new harness is the stator wire and just goes back into the alternator. The resistor on the green/red wire is not required, I did not use mine, but I dont see a problem using it if you want to. There is a black/orange B+ wire (the charging wire) that I taped up into the new harness (we will still need to make this a hot wire, or at least I had to because of an AC circuit in the ICM)

    Now for the fusible link:
    Over by the starter solenoid (probably different on the gen2 cars since the solenoid is part of the starter) on a post there were a number of connections, many of which for the interior's power supply. One of these connections has a pretty large fusible link, and then later down that part of the harness has another fusible link leading to a yellow wire, and the other part (without the second fusible link) being a orange/black wire (mine was 10 gauge, yours could be different). These are your B+ and regulator wires and where the circuit protection is located for them. Since we arent using the Black/Orange wire as a B+ anymore, and it will just be a supply for the AC part of the ICM, we dont need to cut anything on it, the yellow wire however needs to have its fusible link cut out of it, and replaced with an 18 gauge fusible link (per the 95 shop manual), then both wires need to be reconnected to power (make damn sure that the Blk/Org wire we removed near the alternator is NOT TOUCHING A GROUND and is safely sealed away with plenty of electrical tape in the wiring harness before you connect these, or at least before you connect the battery back up. That is it for the wiring!

    Now all you have to do is wire up your appropriate power wire to the alternator and put in some kind of circuit protection, I recommend a circuit breaker because its easy, or you can use a fuse, between your alternator power wire and the battery.

    Here are some pics:

    [​IMG]
    [​IMG]
    [​IMG]

    Heres a pic of the spacer for the dipstick:
    [​IMG]

    Keep in mind that I replaced the old starter solenoid with a 200 amp circuit breaker (and installed a gen2 starter). Which is why there is no solenoid in the pictures :p.

    I know its a big mess, let me know if you guys have any questions.
    Mike
     
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  2. rktmn

    rktmn SHO Member

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    Mike,

    Thanks for the write up. That was quick. I have to get to work, so I have not had a chance to read it carefully. I will do that when I get back from work this afternoon.

    How much did your alternator shop charge you for the rebuild?

    Thanks.

    Jose
     
  3. element913

    element913 SHO Owner Elite

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    The bracketry and core alternator from the junkyard was $75.
    The alternator rebuild was $1 per amp, so $185.
    The Harness upgrade was $19 shipped.
    The Circuit Breaker was $20 shipped off ebay.
    The 2 gauge wiring (8 feet) was $40, that I got at a local marine shop.
    Room for misc expenses, about $50

    Total cost: about $389 (which is alot for an alternator, but my stereo needs juice bad, my mcintosh amp draws a lot of current!)

    Thanks,
    Mike
     
  4. rktmn

    rktmn SHO Member

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    Mike,

    Thanks again. I saved your post so I can do this mod in the future. I wish I had this info a couple of months ago, because, this was exacly what I was looking for when I replaced my alternator.

    For now it is working fine, but I have always been a fan of big amp alternators.

    I know that when I have all my accessories on at the same time, plus my sound system, my voltage output drops to just under 12volts. Not good.

    I will start collecting the parts.

    Jose
     
  5. element913

    element913 SHO Owner Elite

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    Oh and I almost forgot, you will need a new AC/Alt belt, one for a 94-95 MTX, which napa unfortunately had the wrong size for. I dont remember the length

    -Mike
     
  6. element913

    element913 SHO Owner Elite

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    Oh and I had to move the coolant resivoir to the right about an inch and cut the corner of the plastic cover to clear the connector on it.

    -Mike
     
  7. element913

    element913 SHO Owner Elite

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    The 200A circuit breaker crapped out on me yesterday. I guess it was a cheap one, so I replaced it with a 200A MEGA-FUSE and no problems so far.

    I do NOT recommend putting in a circuit breaker, and although my stereo one has been working fine for 2 years now, I am considering replacing that with a MEGA-FUSE as well just to avoid any future issues.

    -Mike
     
  8. ant-live

    ant-live SHO Member

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    How is this upgrade helpfull? :confused:
     
  9. element913

    element913 SHO Owner Elite

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    If you have a large stereo, or some other necessity for alot of current output, this is useful. My stereo draws over 140A at max output (Mcintosh amps EAT current). This thread should probably be moved to Electronics and Audio.
     
  10. SolidState

    SolidState No Mo SHO

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    This needs to be put into a FAQ section....wonderful writeup.
     
  11. BlackonBlack89

    BlackonBlack89 SHO Member

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    there is a how to section and nice write up

    *STICKY*
     
  12. 93rev2sev

    93rev2sev SHO Member

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    I second

    "Sticky Status" Worthy
     
  13. Racer X

    Racer X SHO Pilot

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    Cosigned! :thumb:
     
  14. ManySHOs

    ManySHOs []=[] []

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    I'm revisiting an old thread here because I plan on doing this soon and finally have all of the parts I need. At first, I found the pictures of the wiring to be a little confusing but for a 92-95 mtx this should be pretty straightforward because our starter solenoid is mounted on the starter itself. We shouldn't need to run any wires over to the fender or do anything more than plug the harness in and run a heavier gauge, fused charging cable. (I hope)

    I purchased my harness from rjminjection instead of PA Performance. They have a great writeup on their site about installing 3G alternators on a Mustang. With the harness adapter, 2 gauge cable and a MEGA fuse, this is a pretty straightforward swap.

    http://fordfuelinjection.com/?p=75

    I'll post pictures and results when I'm done. Thanks for doing the legwork Mike!

    Ian
     
    Last edited: Jul 29, 2007
  15. Ishodu

    Ishodu Moderator Staff Member

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    Now that I have seen this its been added to the How Do I section and Sticky. Good write up.
     
  16. ManySHOs

    ManySHOs []=[] []

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    Mike (If you're still subbed to this thread)

    You mentioned that you need to make the yellow wire hot because of a circuit in the ICM. Do you know the purpose of the yellow wire in our wiring harness? The RJM harness adapter loops the "A" output (yellow wire) right back to the charging output stud. That makes the output hot but unless I splice a lead into the factory harness the yellow wire in the harness is just going to hang out there. I noticed that this is the major difference between the RJM and the PA Performance harness.

    [​IMG]

    Wiring Diagram

    [​IMG]

    Harness

    I'll have to look at my 94 Helms to see if there is a wiring schematic that tells me what that yellow wire does on the 94-95 and see if I can find a schematic for the earlier cars. I believe it needs to see the alternator output and send that to somewhere. If that's the case, I'll splice a lead into the loop to make it a Y cable. What did you end up doing with yours?

    It's my understanding that the green wire is a switched lead with a resistor inline that illuminates the charge light in the dashboard. I'm unsure if the resistor is already there, needs to be used or can be ignored. Why did you choose to not use one?

    Thanks!
    Ian
     
  17. llamaking122

    llamaking122 Green Machine

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    Really wish i had one right now!
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    can i use a 94-95 atx if i have a 92 mtx its the bracket etc but can i get it and use it
     
  18. ManySHOs

    ManySHOs []=[] []

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    I'm not sure what you are asking but you need to use all mtx parts for this upgrade.

    Ian
     
  19. llamaking122

    llamaking122 Green Machine

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    well there is a guy parting out his 95 atx and i wanted to see if i cud use the bracket and alternator on my 92 mtx
     
  20. jonheese

    jonheese Know-It-All

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    ORLY? Surely you're done by now, aren't you, Ian? ;)

    I'm looking at doing this on my '90, since I've got the engine out and everything's easy to swap.

    I'm also thinking about switching to a Gen2 starter at the same time, as this would simplify things, right? Would this just be a simple matter of ditching the fender-mounted solenoid and running the (new) power cable directly to the starter-mounted solenoid? Anything else I should know before attempting this (I haven't yet gone and looked at the car to sanity-test this plan)?

    Are the 3G alternators on RJM Injection all Mustang-only? None of them look like the cases match my old (current) alternator...
    http://www.rjminjectiontech.com/?p=6

    Anyone have a source for 3G SHO alternators cheaper than $124.89 (Rockauto http://www.rockauto.com/catalog/raframecatalog.php?carcode=1138957&parttype=2412)?

    Thanks in advance for any advice on this plan.

    Regards,
    Jon Heese

    Edit: FYI, I found alternators on eBay for significantly less than Rockauto:
    Remanufactured $76.50 + shipping
    Brand new $89.95 + shipping

    And a starter too:
    Remanufactured $77.95 plus shipping
     
    Last edited: Aug 19, 2009

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