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I'm running into the issue where I run the head-lights, heater-fan, and stereo, and my volts will go down to 12.3 to 12.1 volts.
I replaced my battery, redid all the battery connections and it did make a difference. I used to get 11.9 volts under high load. But now I am thinking about changing the alternator.
My research has showed me that an 86 S4 RX7 N/A is supposed to have a 60 amp alternator.
I thought I'd ask about and see what people had to say.. . .I'm not the first one wanting more juice.
I also want to replace the 2 wire connector. . . .Where do I find that connector?
Series 5 and FD alternators require a minor wiring change, but offer 80A and 100A respectively. You just need the pigtail to make a little adapter harness, and the diagram is out there if you search for "S5 alternator into S4". I think the wiring between S5 and FD units are the same.
After that, you could go to the 130A Taurus alternator. Requires a similar wiring change, plus a new charge cable since I don't think running 130A through the stock charge cable is a good idea. Plus fuses to match, a small bracket for the mounting, and swapping to a v-pulley. There is a thread called "130A Alternator Sweetness" that goes into detail and includes diagrams. Be careful, there were also 95A units for some Taurii that look fairly similar. Make sure you get one that looks like the photos.
If you need more than that, you can have the Taurus alternator rewound. I bought a reman unit that outputs 170A. Way overkill, but I'm not complaining.
I can take some photos tomorrow of the Taurus setup if you're interested.
Skip straight to a 130A Taurus Alternator, you won't be disappointed. It uses the same Retrofit Pulley as a FD alternator does in a FC. The correct wiring info is in my profile gallery.
I can take some photos tomorrow of the Taurus setup if you're interested.
just for the sake of clarity, that Ford 3G alternator that you referenced in your build thread is the same as the Taurus alternator? if so, in your thread, you mentioned something about there being two of them, is there any way of knowing the difference from a photo?
just for the sake of clarity, that Ford 3G alternator that you referenced in your build thread is the same as the Taurus alternator? if so, in your thread, you mentioned something about there being two of them, is there any way of knowing the difference from a photo?
There are some subtle differences, and conveniently I now have both versions. I can take some photos today and try to document the differences.
The way it works is that it's a Taurus alternator, but also came on other Fords (Mustangs, and I think some others). Ford calls it 3G because it's the third generation of Ford alternator (apparently, I don't really know Fords).
The frustrating thing is that there's a 95A model of Ford 3G as well that certain Taurii got, plus subtle variations in different case designs from one application to another. So I originally got a Taurus alt from a junkyard a few years ago and built the bracket for it. Then recently when I wanted a rebuilt unit, I grabbed one off Amazon (listed for a Taurus, 170A IIRC), and it was just slightly different which made it not fit my bracket properly and not quite long enough for the adjustment slot. I assume one could design a new bracket that would work for this model but I already had my old one so I swapped the guts into my original casing.
Here's the original thread showing the bracket and alternator:
The way it works is that it's a Taurus alternator, but also came on other Fords (Mustangs, and I think some others). Ford calls it 3G because it's the third generation of Ford alternator (apparently, I don't really know Fords).
on a car that old Ford used many different alternators, and they didn't keep track of, well; anything until the mid 2010's. so the catalog is a page of alternators it could be, and you match yours to it. this works ok with the alternator, not so much with the belt....
I'm running into the issue where I run the head-lights, heater-fan, and stereo, and my volts will go down to 12.3 to 12.1 volts.
I replaced my battery, redid all the battery connections and it did make a difference. I used to get 11.9 volts under high load. But now I am thinking about changing the alternator.
My research has showed me that an 86 S4 RX7 N/A is supposed to have a 60 amp alternator.
I thought I'd ask about and see what people had to say.. . .I'm not the first one wanting more juice.
I also want to replace the 2 wire connector. . . .Where do I find that connector?
F651-18-300B is for an 80's Mazda pickup... 55amp is not 60amps... the 86-88 turbo had a bigger alternator that bolts in, although it may be that the Ford or FD alternator is a better idea in 2022
on a car that old Ford used many different alternators, and they didn't keep track of, well; anything until the mid 2010's. so the catalog is a page of alternators it could be, and you match yours to it. this works ok with the alternator, not so much with the belt....
Yeah, it can be a more than a bit ambiguous. I did find some differences which will help people determine which is which though:
This is the one actually on my car. This one has seen a few different rebuilds, but it 100% came out of a mid-90s Ford Taurus. And if I recall correctly it was the OHV engine, but this was a few years ago now. You can also see the bracket; it's a fairly simple piece to make if you have access to a welder.
This is the one I got from Amazon and later took the guts from to transplant into my original casing. There are two noticeable differences: The length from mount to adjustment ear and the lack of threads on the adjustment side.
The stator is the same size and so is the center part of the casing, but the mount and ear both tuck closer to the casing than on my original alternator. This meant that when installing it, the bracket was interfering with the alternator casing before the bolts lined up.
And of course on the original alternator the ear is threaded for the adjustment bolt (M8x1.25), whereas on the newer one it's unthreaded so you'll need a bolt and nut.
I don't see why the second style wouldn't work as long as you design the bracket differently.
Parts list (as far as I remember):
- Alternator
- 4ga cable for the charge cable.
- Pigtail for the alternator side (Ford calls it a "breeze" connector, I think).
- Two pin connector that matches the harness side, so you don't have to cut the original harness. Carried on Eastern Beaver Connectors, but forget the exact model.
- Smaller gauge wire for the charge sense connection.
- 150A fuse for the alternator charge wire.
- 30A fuse for the sense connection.
- Materials for bracket and access to welder to make it.
- Pulley (I think it's a 17mm bore) or dual pulley if necessary. The guy at the alternator shop gave me this one for $10, so I don't know where it came from unfortunately.
- Belts. It would be useless to list a size since the bracket is custom, but I'm using two kevlar 3L340 so that would be a good starting point. If your local automotive place is cool they'll let you return a belt that didn't fit, as long as you didn't run it.
And that should be it. The wiring diagram is in the thread I linked earlier.
EDIT: Here we go, you're looking for the two-pin Yazaki:
The ford contour 3G version 130amp alternator (95-97 L4) fits in nice as you can use the stock air pump bracket and it makes a nice clean looking install. The only goofy thing with these is they are next to impossible find in any snow belt area wreakers as they are long gone to rob for the 3pin connector from . It's a not common connector on north american cars. Here's the info on the connector under post #42 Replacement Connectors - RX7Club.com - Mazda RX7 Forum . That's what i used and it is the correct connector.
Coming back to want vs need. I don't see an issue with a stock s4 alternator if you're not running an e-fan or big sound system.
Are you taking the voltage readings at idle or while driving?
Coming back to want vs need. I don't see an issue with a stock s4 alternator if you're not running an e-fan or big sound system.
Are you taking the voltage readings at idle or while driving?
Even with just a simple radio installed, you can literally see the voltage on the stock voltmeter drop to 12.0 flat just by turning it on. And we're not talking about high end stuff either, a basic radio from Walmart with 4 50w speaker channels is enough to push a stock FC alternator into failure. This is actually what led me to join the forum back in 2007.
For a car that will be staying bone stock, I suggest a FD alternator. Otherwise, just skip to a Taurus Alternator. 92-95 Taurus/Sable with a 3.0 or 3.8 OHV engine, can also get them from a 93-96 Windstar with a 3.8. Your car will thank you by not leaving you stranded with a dead battery ever again. As for connectors, the Yazaki 2-pin "T" connector is pretty common on 80s-90s Japanese small cars. If all else fails, you can use a Male Quick Disconnect as you only need one of the 2 pins on it for Switched 12v. The rest can be done at the Fuse box for Sense. See my profile gallery for how to wire it up properly.
Might visit a salvage yard, you'll be surprised at how the one of the cheapest mods ends up being the backbone of the whole car, and for less than you might think too.
The ford contour 3G version 130amp alternator (95-97 L4) fits in nice as you can use the stock air pump bracket and it makes a nice clean looking install. The only goofy thing with these is they are next to impossible find in any snow belt area wreakers as they are long gone to rob for the 3pin connector from . It's a not common connector on north american cars. Here's the info on the connector under post #42 Replacement Connectors - RX7Club.com - Mazda RX7 Forum . That's what i used and it is the correct connector.
we have a guy at work, or at home or whatever, who has one of those cars, and those things are rare now. we think we have it rough with the Rx7, but try a 90's Ford sometime, its cold out there!
Coming back to want vs need. I don't see an issue with a stock s4 alternator if you're not running an e-fan or big sound system.
Are you taking the voltage readings at idle or while driving?
the charging problem on my 20B car turned out to be the STAPLE between the alternator wire and the harness, worth a look...
My volts, as read by a cigarette lighter volt meter, and after 15 mins driving, reads 13.2 with nothing on.
With everything on, it goes below 12 volts at times. I have a stock fan, but I do have a mid sized stereo. I'm in the process of changing all the lights to LED's to further reduce the load on the system.
My dash volt meter is intermittent and it reads low when it does work.
The wires going to the back of the alternator/connector are old and starting to lose their insulation.. . .The wires look oxidized and look like they are going to break.
I agree that a stock S4 alternator which is properly rated, and not the current alternator I have, is the easy and sensible way to go right now.
I did learn a lot on this thread, particularly the wiring and the connector type, and now I have thread with all the info I need to do a swap/mod.
All this time I thought my alternator was correct. . . Never knew it came from a 80's truck or 323. . .I never knew it was underrated till I went through this exercise.
Let's see what I get when I replace the connector and put a new/rebuilt unit in.
Hello,
My volts, as read by a cigarette lighter volt meter, and after 15 mins driving, reads 13.2 with nothing on.
With everything on, it goes below 12 volts at times. I have a stock fan, but I do have a mid sized stereo. I'm in the process of changing all the lights to LED's to further reduce the load on the system.
My dash volt meter is intermittent and it reads low when it does work.
The wires going to the back of the alternator/connector are old and starting to lose their insulation.. . .The wires look oxidized and look like they are going to break.
I agree that a stock S4 alternator which is properly rated, and not the current alternator I have, is the easy and sensible way to go right now.
I did learn a lot on this thread, particularly the wiring and the connector type, and now I have thread with all the info I need to do a swap/mod.
All this time I thought my alternator was correct. . . Never knew it came from a 80's truck or 323. . .I never knew it was underrated till I went through this exercise.
Let's see what I get when I replace the connector and put a new/rebuilt unit in.
Thanks
Can I make a suggestion, based on firsthand experience? If you're going to go through the trouble of doing the work, value your own labor. Do it right the first time and stop trying to self-cripple your car. It's a known fact that S4 alternators were barely able to cover the needs of a stock car. It was the first thing I learned when I got mine in 2007. Also, unless it is NEW from the dealer (Read: weak) and verifiably made by Mitsubishi Electric Co., a S4 alternator from ANY parts store will be garbage, guaranteed and you'll be replacing it again before you know it.
Also, you won't notice the difference between 60 amps (1986 323 alternator) and 70 amps (S4 alternator). They're just too wimpy for the car, period. A Taurus Alternator on its worst day, will outperform a stock S4 alternator at it's best. I've had one trip a 150A circuit breaker through 17ft of 4awg cable when its voltage regulator failed, so a fair estimate of their peak power is roughly 170-180A. It's just a better part overall. Plus, they're fairly common at any U-pull-it type salvage yard for $20. One other nice thing about them is that since it's a Ford 3G Alternator, they're very well understood and easily rebuilt. Replacing a Voltage Regulator is maybe a 30-minute job, there are plenty of guides on Youtube and the parts to do so are dirt cheap on Ebay.
Can I make a suggestion, based on firsthand experience? If you're going to go through the trouble of doing the work, value your own labor. Do it right the first time and stop trying to self-cripple your car. It's a known fact that S4 alternators were barely able to cover the needs of a stock car. It was the first thing I learned when I got mine in 2007. Also, unless it is NEW from the dealer (Read: weak) and verifiably made by Mitsubishi Electric Co., a S4 alternator from ANY parts store will be garbage, guaranteed and you'll be replacing it again before you know it.
Also, you won't notice the difference between 60 amps (1986 323 alternator) and 70 amps (S4 alternator). They're just too wimpy for the car, period. A Taurus Alternator on its worst day, will outperform a stock S4 alternator at it's best. I've had one trip a 150A circuit breaker through 17ft of 4awg cable when its voltage regulator failed, so a fair estimate of their peak power is roughly 170-180A. It's just a better part overall. Plus, they're fairly common at any U-pull-it type salvage yard for $20. One other nice thing about them is that since it's a Ford 3G Alternator, they're very well understood and easily rebuilt. Replacing a Voltage Regulator is maybe a 30-minute job, there are plenty of guides on Youtube and the parts to do so are dirt cheap on Ebay.
So the real question is: Why wouldn't you?
Or if OP doesn't want to make the bracket and wiring, the S5/FD alt just requires a small pigtail to fit. Not as much output as the Taurus alt but still way better than the S4.
Having tried a few S4 alternators before my current Taurus alt, they all had the same issue. Even a brand new one is unlikely to be adequate.
EDIT: And the FD alt requires you to swap the pulley over from your original alt, of course.
Or if OP doesn't want to make the bracket and wiring, the S5/FD alt just requires a small pigtail to fit. Not as much output as the Taurus alt but still way better than the S4.
Having tried a few S4 alternators before my current Taurus alt, they all had the same issue. Even a brand new one is unlikely to be adequate.
EDIT: And the FD alt requires you to swap the pulley over from your original alt, of course.
Any alternator upgrade requires wiring work and swapping the pulley, period. I've done both FD and Taurus Alternators in the same car and I gotta say that getting an alternator pigtail for a Ford Taurus is 100x easier, cheaper and faster than trying to find one for a FD. There is merit in using the same connector across Ford's entire lineup for over a decade. Even my Expedition has a 3G alternator with the same regulator and pigtail on it. Just a different case to suit a Triton V8, otherwise it is identical.
As far as output is concerned, I'm going to go out on a limb and say they are measured differently between Mitsubishi (Mazda's supplier) and Delphi (Ford's supplier). Best way I can describe it is like an amplifier's Peak wattage vs RMS wattage. Digging in the Eunos Cosmo Workshop Manual, I found that at Idle, 60A is the minimum to say that the alternator is "good", and the same spec was used on the FC too. So just shy of 2/3 of it's capability is required at idle on a Cosmo, and 85% of maximum power on a Series 4 RX7, just to keep the engine running. Unfortunately, it's just the nature of how Japanese cars are made, by trimming as much "weight" whenever possible so the least expensive alternator can be used. Even in 1995, they were still using them on the Mirage, rated at 75 amps and could get away with it because its ignition system wasn't nearly as thirsty as found on a Rotary. Some were still using a Dizzy then. Plug and mounts are identical to a S5 RX7 too. That gave it more "overhead space" so it wouldn't be affected by a simple radio install like the RX-7 is.
Even the beefiest stock alternator of this lineage/design maxes out at 110A (Mitsubishi 3000GT) and I'm certain it can't sustain that output for more than 30 minutes as it takes 60% of it to keep the car running at idle. Same plug as FD/S5 too.
The Ford 3G alternators are just a stronger design overall, and this is because it was necessary to feed a 3.8L with a 2-speed electric fan. Since the fan comes on at idle or crawling along, drawing a constant 20-30A, there was no choice but to increase the output when the alternator was turning at its slowest. Otherwise, they would be eating alternators on a daily basis which looks quite bad from a financial/warranty perspective. I'm not sure what the idle output spec is offhand, but I'd wager it is probably around 90A and the "130 amp" rating is quite conservative. In Test Mode, the specification is 150A.
While typing this, I just checked in my Ford EVTM and found that at 2000rpm of Engine Speed, the absolute minimum output for a Ford 3G alternator is 87 amps sustained. So at idle, 80 amps "RMS" on a Ford 3G vs 70 amps "peak" on a S4 alternator.
So at the end of the day, a Taurus Alternator is a bit stronger at its weakest moment than a stock S4 alternator can be at its absolute best, and can stay there all day long too. This is why I swear by Ford 3G alternators.
02-07-22, 08:45 PM
