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Index > Engine/Drivetrain > Thread: How to install FD/FC alternator
Thread: How to install FD/FC alternator [' This thread is 2 pages long: (1) 2 ']
mwpayne1


Redlining
Posts: 239
posted April 03, 2012 05:15 PM

How to install FD/FC alternator

Any of you guys that have done this swap, can you please step me thru how to modify the wiring?

       
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Brad


Rotorhead
Posts: 1665
posted April 04, 2012 12:29 PM

quote:
Any of you guys that have done this swap, can you please step me thru how to modify the wiring?


Run the large + battery cable to the alt output per the norm.

Run a new wire from the upper male connector on the alt to the + battery terminal. This is used for the alt to sense if the battery needs charging. If you don't do this the battery will drain when the motor is off.

Leave the lower male connector on the alt empty. Remove the voltage regulator. Unplug the 6 pin connector it connects to on the inner fender and electrical tape it up.

The red alt warning light on the dash won't work right and the bulb should be removed.

I used the dual belt alt pulley from Japan2LA. It is quality, aluminum, and the correct diameter.
http://www.rx7club.com/showthread.php?t=860871
I used to use another one commonly sold, sourced from a dodge caravan or some nonsense but the diameter was larger and it underdrove the alt.
____________
-brad-
74 REPU Lawn Green
81 Rx-7 racecar. 12a J-
Bridge

       
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chuyler1


Hauling
Posts: 137
posted April 05, 2012 09:52 AM

What is the benefit of this swap?

       
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Brad


Rotorhead
Posts: 1665
posted April 05, 2012 03:02 PM

Stock alt puts out what, 55 amps?

FD is 100amps.

More juice.

       
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jm1fd


Revvin Up
Posts: 83
posted December 14, 2012 06:14 AM

quote:
Leave the lower male connector on the alt empty.


If you do this, you won't reliably get output from the alternator, reason being the FD alternator isn't self exciting. It needs just a tiny bit of current to excite the field in order for it to start producing output.

The Y/R wire from the light on the dash should be wired to this terminal (at least for a 1977 model REPU...other years may vary, but I doubt it). It will provide the necessary energy to excite the field, and if a fault occurs and the internal regulator decides it is time to turn on the light, on comes the light!


       
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spokanerxdude


Hauling
Less cubes... More balls
Posts: 181
posted December 14, 2012 07:14 AM

Isn't there something you have to do with a relay to make the choke work normally. Think I remember reading something about that somewhere.

____________
Allen Ervin, spokanerxdude@yahoo.com
509-998-9024

        Click here to visit Spokanerxdude's homepage. 
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jm1fd


Revvin Up
Posts: 83
posted December 16, 2012 06:51 AM

quote:
Isn't there something you have to do with a relay to make the choke work normally. Think I remember reading something about that somewhere.



Probably. I didn't have to contend with that since when I was removing the emissions crap from my harness I wired the temperature switch in the thermostat housing so that it directly controls the magnet at the choke knob. No more choke relay for me.

       
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Xp882


Redlining
Posts: 290
posted March 25, 2015 09:30 AM

quote:
quote:
Any of you guys that have done this swap, can you please step me thru how to modify the wiring?


Run the large + battery cable to the alt output per the norm.

Run a new wire from the upper male connector on the alt to the + battery terminal. This is used for the alt to sense if the battery needs charging. If you don't do this the battery will drain when the motor is off.

Leave the lower male connector on the alt empty. Remove the voltage regulator. Unplug the 6 pin connector it connects to on the inner fender and electrical tape it up.

The red alt warning light on the dash won't work right and the bulb should be removed.

I used the dual belt alt pulley from Japan2LA. It is quality, aluminum, and the correct diameter.
http://www.rx7club.com/showthread.php?t=860871
I used to use another one commonly sold, sourced from a dodge caravan or some nonsense but the diameter was larger and it underdrove the alt.



Looks like this guy is long gone.. Is there anywhere else you would suggest to get the pulley?

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Brad


Rotorhead
Posts: 1665
posted March 25, 2015 11:52 AM

Haven't looked for one in years. Google is your friend!

       
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spokanerxdude


Hauling
Less cubes... More balls
Posts: 181
posted March 26, 2015 05:50 AM

I think Atkinsrotary.com has pulley 's
____________
Allen Ervin, spokanerxdude@yahoo.com
509-998-9024

        Click here to visit Spokanerxdude's homepage. 
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rotarydave2006


Revvin Up
Posts: 53
posted March 26, 2015 01:27 PM

Mazdatrix has them.i think I already mentioned it in a text earlier :)

       
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Xp882


Redlining
Posts: 290
posted April 18, 2015 12:41 PM

quote:
Any of you guys that have done this swap, can you please step me thru how to modify the wiring?


Run the large + battery cable to the alt output per the norm.

Run a new wire from the upper male connector on the alt to the + battery terminal. This is used for the alt to sense if the battery needs charging. If you don't do this the battery will drain when the motor is off.

Leave the lower male connector on the alt empty. Remove the voltage regulator. Unplug the 6 pin connector it connects to on the inner fender and electrical tape it up.

The red alt warning light on the dash won't work right and the bulb should be removed


Brad you used the stock red white battery plug from the Repu to post or you ran a new large cable from the batt?

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sparky


Redlining
Posts: 299
posted April 19, 2015 06:53 AM

I've upgraded the alternator. It was a long time ago and since i've redone all electrical on the truck. I remember i had to disconnect the voltage regulator and install a jumper across 2 wires on the 6 pin connector to the voltage regulator. I found a photo on the forum showing which wires to jumper.
____________
'77 REPU
Stock 6-port
T-2 tranny
Weber IDA 48
Alum Flywheel
3rd gen Torsen in rear end.
DLDFIS ignition

       
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sparky


Redlining
Posts: 299
posted April 19, 2015 08:48 AM

Check out the photos in this thread.
http://www.mazdarepu.com/board/viewthread.php3?FID=1&TID=165
____________
'77 REPU
Stock 6-port
T-2 tranny
Weber IDA 48
Alum Flywheel
3rd gen Torsen in rear end.
DLDFIS ignition

       
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Brad


Rotorhead
Posts: 1665
posted April 20, 2015 09:03 AM

XP882, You can use the stock repu white/red wire with the FD alt, but I ran a new thicker gauge cable from battery to fusable link box, all the way to the fusebox and the alt.
____________
-brad-
74 REPU Lawn Green
81 Rx-7 racecar. 12a J-
Bridge

       
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Xp882


Redlining
Posts: 290
posted April 20, 2015 11:50 AM

Thanks guys!

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Xp882


Redlining
Posts: 290
posted April 20, 2015 11:53 AM

Brad I just leave that 6 pin and the two other wires disconnected or do I need a jumper like sparky?

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Brad


Rotorhead
Posts: 1665
posted April 22, 2015 07:45 PM

quote:
Brad I just leave that 6 pin and the two other wires disconnected or do I need a jumper like sparky?


2 days ago I ran a wire from the Yellow/Red stripe wire on that 6 pin connector to the L port on the alternator (the lower port viewed when the alternator is insatlled). As an exciter wire. It works, and if the alternator's internal regulator fails, the G lamp on the dash should light up.

Be sure to run a small wire from the S port on the alternator (the upper port viewed when the alternator is installed) to the + battery terminal. That way the alternator can sense battery voltage and know when to charge. And...otherwise the alternator will drain the battery once the truck is turned off.

L = Lamp
S = Sense
Easy to remember now!

I have not jumpered any of the wires.

       
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Xp882


Redlining
Posts: 290
posted April 23, 2015 01:12 AM

Thanks brad! Will do

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Xp882


Redlining
Posts: 290
posted May 29, 2015 07:52 AM

Brad what belts/ sizes did you use?

Thanks Adam

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