Alternator upgrade - wiring
 

hi guys,
need to confirm some things on installing FD alternator into my GSL-SE. what i'd like to know is if i can use the existing alternator harness or do i need to run new thicker wires and if so, which wire(s) should be upgraded and how thick? same thing with the wiring on the front harness.

looking at the following links, it seems like i could simply wire in the FD alternator connector in place of the FB one?
https://www.rx7club.com/1st-generati...stion-1011841/

https://www.rx7club.com/1st-gen-non-...tor-fb-850367/

or do i need to make sure that Terminal S goes to it's own dedicated fuse?

here's my existing harness:
https://lh6.googleusercontent.com/-a...s800/photo.JPG

thanks

Here

thanks siraniko. i did see your pic on another thread as well so confirm this for me then...

are you joining the Post(WR) and Terminal S together (thus not using the BW wire) which then goes to + on the battery, and then Terminal L uses the "dash" wire? that simple?

One thing, be sure to upgrade to a bigger wire going to the battery. Unless you like fire. That scrawny stock wire isn't up to the task of a high-output alternator.

I dont remember the terminal letter designation but heres another one. For best result, upgrade your fusible links to FC (large fuse to match the fd alternator) as well as the b terminal to fuse block to a larger cable

Fred,

I have done FD alt installs into my old 85 GSL and my SA. The FB is way easier and very straight forward. Due to all of the alternator issues I had with the SA, I have lots of resources for this on my computer. Once I get my baby and his mama home and can get to my computer, I'll get you everything you need.

Just figured out a way to help you sooner. Sending you a PM.

I've already replaced the fusible link with a fuse box. Looking at the pic, I would assume there is another wire that runs from the post to the battery.

Donnie, if you've got info, please share. :)

I may even consider moving the battery to the rear bin if you've got info on that as well. Thanks.

Battery relocation info would be nice. Have to move my battery to make way for FMIC piping.

There are several battery relocation/alternator threads already if you will use the search button. It takes time but its out there

I'll be researching myself on the battery relocation but I do believe I've got the alternator wiring figured out.

L connects to existing W/B wire on front harness
S will be a new fused wire from the fuse box
B will be a new wire directly to the battery

B terminal to fuse box 80amp. The other side of 80amp goes to battery

alright, so there are lots of opinions on how to do the wiring for the alternator swap. this is most likely my final iteration which now includes relocating the battery to the rear passenger side bin. i may add an inline fuse from the battery to the starter though (siraniko is a big proponent of this from what i have seen). here's a drawing including wire sizes i'm proposing to run:

https://lh6.googleusercontent.com/-j...s800/photo.JPG

actually, not my final iteration. depending if i put an inline fuse at the battery to the starter, my wiring would likely change. with the above, i would at least change the 10 GA wire from B to fusebox to be a 6 GA wire.

I haven't done this yet.. But there are some great threads on Ausrotary about it aye.

AusRotary.com • View topic - Alternator upgrades

AusRotary.com • View topic - S6 Rx7 altenator into S2 Rx7


Heres a good one about moving the battery into that hatch/bin area also:icon_tup:

AusRotary.com • View topic - MOVING A BATTERY FROM ENGINE BAY TO THE BOOT!!


Hope they help!:nod:

I would put a direct negative line from the battery to the starter like the factory one goes. Since the battery is in the rear it will also be closer for a ground wire. Then I would run another from the starter to the strut tower like the factory does. For good measure, I also ran a ground from the alternator to the strut tower.

thanks jsmall.

kansas, i understood everything but the one about ground from alt to strut tower. where is there a negative on the alternator?

I attached a two foot battery ground cable from the rear of the alternator bolt. I powder coated by alternator and was having charging issues. This will eliminate and grounding issues for the charging system.

ahhh, i see. so the body of the alternator is grounded (since it's attached to the engine)...now i understand. electrical newbie here. thanks.

I will caveat anything I say with... electrical gremlins are extremely annoying.

That has led me to use a 185 amp (i think) gm alternator on my 83 gsl with the stock positive wire for charging the battery. I can get the part number and pics of the setup if you are interested. I ended up using some 0 or 1 gauge wire as the primary ground from the alternator pivot bolt to the stock chassis ground location on the drivers strut tower. I planned this to serve as the primary engine ground as well. As far as I understand the voltage regulator, the alternator will only provide enough voltage and current as the system requires. This is why the stock positive charging wire has not melted. Although if the regulator goes bad...

I used to run a self powered infinity basslink sub, head unit, some infinity kappa 4 inch rounds up front and 6x9's in their own enclosures in the rear. I have since removed all of that and have no noise making device other than the engine and exhaust. Those keep me plenty satisfied as of late.

To get the gm alternator to fit required a little grinding and a few test fits. That was 4-5 years ago and hasn't given me an issue since. I tend to try and fix things by overdoing the fix... hence the zero gauge wire. I still have a bouncing voltmeter/fuel pump hum when my turn signals are on but everything else seems strong.

I have also had an issue where a brand new optima red top battery sat over the winter, not on a trickle charger, then I brought it back with a slow charge and used it on a 10 hour trip. Don't know if it was my setup or the battery going dead over the winter but the top seal broke and started leaking and smoking while I was on the highway. Regardless, i've since learned that dry cell batteries should never get drained to nothing. Bad things happen to the plates. That was a tangent...

just my 2 cents and re-read the thread... way off topic. Good luck with your wiring.

I got a fd alternator and I'm putting it on my '80.
Can't wait for this project.

I'm putting an FD alternator in my FB. The FD alt shaft is 17mm, while the FB alt shaft is only 15mm. FC pulley and spacer?

No. Just drill or file the FB pulley to fit the FD shaft.

There's a spacer that's required there (just like the FB installation). What did you do with that?

Forgot what I did. I had three alts to play with fb, s4 fc, and the fd. I was able to make it work with what parts I had from those.

Here's how I wired up my modded S4/S5 hybrid alt to fit my '80, with battery relocation.
4ga wire from battery to positive terminal on starter.
4ga wire from alternator to positive terminal on starter.
Factory (10ga?) wire from alternator into harness.
Additional 8ga wire from alternator to ignition switch.
Wire from L terminal to a dummy light (or you can wire yours up to your dash light)
Wire from S terminal to switched 12v (on in RUN)

It seems to be working out right. The only issue I have is that when the car is off with the battery left on (I have a disco switch) the alt charges at 13V instead of 14V next time I drive. I think this is an issue with the alt itself.

ETA: Note that if you plan to use the car for sanctioned racing, you will need to wire the alt to the BATTERY side of the disco switch (instead of daisy-chaining through the starter terminal), so it cuts all power to the chassis when you switch it to "off".