jutny

Hey guys, i know there are a few of you that have put an FD alt into your 1st gens. I have my FD Alt sitting on the table in front of me, and my crappy 55 amp alternator left me stuck on Rt.81 between Lafyette and Syracuse last night and cost me $100 for a tow to a place where i could fix the damn car.

Anyway, anyone know which terminals on the FD alt are which, and which terminals on the SA/FB wiring plug are which, so i can match them up.

Other than running the charge wire direct to the battery (as to not kill my fusible links/set things on fire), and adding a ground from the batt. to the engine block somewhere (to help keep the alt safe), is there anything else i have to do. I'd assume it's just make sure the 2 wires are right, and swap the pulley over.

if you've done the swap, gimme the heads up on anything i might run into.

Thanks, Kurt.

gonzz

do a search for alternator swap. they have a picture of both plugs.

slashdawg00110

There's a thread on alt swaps in the FAQ, even has a nice drawing.

jutny

yeah, trust me..... i've read the threads.

problem is, i'm using an FD alt, into an SA.... which is something there is VERY little info about. And what little info there is, is conflicting information.

What is all this LR and LS bullcrap i'm reading here: http://www.rx7.org/public/altxref.html

they say that the s5 80 amp and the s6 100amp require you to do more than just make sure the 2 wires go to the proper place, but many people have said that the s5 80amp is just connecting the two wires and viola. (and i've heard the same thing about the FD Alt)

someone PLEASE explain to me the difference, if indeed there is one (and you dont have to dumb it down, i have good electrical knowledge... just frusturated when everytime i try to do something to my car, there is conflicting information/misinformation given to me, forcing me to be unsure)

anyway, i wanted to get this done tonight, but i'm gonna lose daylight in about an hour and a half, so unless someone knows that's on now, i doubt its gonna happen.

-Kurt


edit: oh yeah, i noticed in one of Mar3's pictures, that he has his new charge wire and the stock one both attached? What should i do, i'm gonna be running 6-8 gauge wire from the post straight to the batt, but should i leave the stock one connected as well? is it used for something other than taking voltage to the battery?

edit2: it appears that my car has an 83 harness in it (which now that i think about it, makes sense, cause the 12a is from 83... but regardless) my alt wires are BW (for the top of the "T" (plug shape)) and WB for the "|" part. (also, were the 89-91 plugs the same as the FD plugs, i have no plug, i'll just use spade lugs, but for continuity of wiring's sake?)

Hades12

the SA has an external Regulator and all the others have an internal. From my reading and questions I get that you have to jump the regulator to take it out of the curcit, I am afraid I do not know anything about the FD Alt.

jutny

i think only the 79 had the external reg, to go along w/ the points ignition (just two elements of crappiness that mazda removed for the next year) Either way, my 80 has an internal reg alt.

i spent an hour or so this evening modding my dual belt pulley to fit the FD alt. I also noticed that the stock FD alt pulley is a lot smaller than the Rotorhead dual belt pulley. I had to bore out the dual belt pulley from .585" to .670", and make a sleeve to fit around the FD alt shaft so the dual pulley dosent sit ON the FD alt casing (which it would without the sleeve). Luckilly i have a nice Logan Lathe, and Bridgeport Vertical mill, so all that was easy.

you guys think the fact that the dual pulley is larger (therefore underdriving the alt) is gonna have a big affect on the charging performance?

hornbm

it'll be fine with it being underdriven, the biggest deal is that it probably wont charge at idle... but at anything higher than 1000RPM it'll be fine

Jeff20B

iTrader: (13)

I agree. LR and LS sounds kinda stupid.

If you have an external voltage regulator, all you need to do is to hook one terminal of the internally regulated alt to a key-ON source and the other to your 'GEN' light. Both of these wires are within the 6 terminal plug of the stock external voltage regulator. I simply removed mine and jumpered the wires. Then I replaced the stock 4 terminal alt plug with a 2 terminal one for my FB alt.

The hardest part was figuring out each wire in the 6 terminal voltage reg connector plug (it wasn't really that hard). After that, it was easy. http://www.mazdarepu.com/Gallery/ind.../connector.jpg

Since yours already has a later wiring harness, it shouldn't be that hard to convert over to a different style alt plug.

jutny

so.... should i just connect my 2 wires to the FD alt's two wires and forget about it?

i just dont understand, it seems to mean that the LR and LS alt's have different requirements for what is on those two wires.



and what's this i've been reading about a voltage drain when converting to which alternators?.... there's just too much different information about the different alternators out there for me to make a decision... i just dont wanna kill my nice new FD alt.

help?

Jeff20B

iTrader: (13)

You bring up a genuine concern, but I have never heard of any problems going from an FB (internally regulated) alt to an S5 FC or FD one (with its funky connector), so logically, since your SA has already been converted to FB wiring, you too should not have a problem going to an FD alt.

I'll wait for others to voice their opinions about the LR and LS stuff before I decide to ignore it fully.

jutny

see, thats exactly what i was thinking... no one has ever mentioned problems with the FD or S5 alt swaps... but theoretically there SHOULD be a problem, because they use two different charging circuits....

we need Max7 in here, he did the FD swap.

edit: i got the alt mounted today, 5 washers held together with some electrical tape, and the FD alt already has the nut mounted in it for the long crossbolt (nice, because i was missing that nut, and have been for ages now... lol) and the FD alts upper ear isnt threaded, but a 5/16 bolt, and some washers and nuts solved that problem. The dual belt pulley is now mounted, and the pullies line up perfectly. If i'm awake early enough tomorrow (today) i'll go and procure some electrical connectors for the alt wirirng, and re-doing the termnials on my battery posts (i dont trust those clamp connectors anymore) from napa.

the alt looks great in there, it makes it look newer in there, with the internal fan, and nicer looking design of the alt itself (its also noticeably larger and heavier) but there were no clearance issues at all, except i had to bend the engine lifting loop out of the way a tad.

Jeff20B

iTrader: (13)

I think the newest alt I'd use is an FC just because its formfactor (or whatever the word is) is closer to FB and older stuff. Then again, the coolness factor of upgrading to newer design, and making it, work can't be ignored. I guess it's up to personal preference.

What are your thoughts about the RX-8 alt? It mounts like a twin dizzy 12A and 10A but I don't know if it would fit '74 to '02 waterpumps.

hornbm

well if you look at my avitar... thats a S5 alternator in my engine bay, 80 amps of POWA

jutny

well, my reasoning for the FD alt is fairly simple.

(2) 80w Headlamps / 100w Highbeams
(2) 65w Foglights
(2) 10" Electric Fans
(1) 1500w Peak Amp
(1) 600w Peak Amp

thats a lot of current draw

also, a FD alt is bound to be newer than a s5 alt, and theoretically less prone to failure by age/mileage. Mounting the FD alt was no problem at all, the only difference is that the output post and input connectors are on the drivers side, rather than the back... like they are in the FC alts. An Rx8 alt would be nice, as they would be even newer/lower mileage, but since they are 100a just like the FD alts, i dont think the trouble you'd have to go through to mount it would be worth it at all. If i get a chance to take a good look at one / snag one somehow you can bet i'll try it.

-Kurt

Jeff20B

iTrader: (13)

Here are some pictures. https://www.rx7club.com/forum/showthread.php?t=238802 The first few are alternators.

Max7

BW for the top of the "T" (plug shape) goes to top plug on FD Alt
WB for the bottom "|" part goes to the bottom plug on FD Alt
Thats how it is on my car

jutny

so you have no problems w/ battery drain? and everything works perfectly?

sweet, now i really wonder what the LR/LS crap is all about, because according to Max7, there is no difference at all. Good for me!

oh, Max7... does yours charge at idle with the dual belt pulley installed (seeing as how the dual belt pulley underdrives the alt compared to the stock FD serpentine pulley.)?

edit: top and bottom? My FD alt has the connector like this: ( -- | -- ) looking at it from the drivers side. The connector is physically on the drivers side of the alt, oriented horizonatally.

Max7

I get about 13.5 at idle, and 14.1 above idle. Makes the Power windows much faster
I've driven it for a month or so, no problems, love it. lights are brighter, stereo is louder....

Max7

mine is up down

jutny

har har... mine is up down too... i'm just a

thanks for the help man, did you hook up your stock charge wire as well as a larger one direct to the batt? I'm wondering if the stock wire needs voltage on it or else some **** wont work.

Max7

I left the plug wires stock, I did upgrade the alt to battery wire though.

jutny

yeah, but did you also connect the stock charging wire, the one that goes to the... fusible link thingy i think?

i think Mar3's pics show one upgrade done with the upgraded wire straight to the batt, and the stock charge wire also connected (i'd assume the stock charge wire is used to feed some parts of the electrical system).

Max7

The stock charging wire goes to the fuseable link, which I removed.
but also doubles back and goes inside the car to the fuse block there.
I have a power wire from the battery to a 2nd gen fuse block now.
my power cables go,
Batt - Starter 2ga (batt is behind passenger seat)
starter - alt 4ga
starter - fuse block 4ga