Box Alternator Question

[friskyfrankie]

Just so there is no confusion here, because this seemed to be hinted at above:
The plug melting is not an intentional feature, and neither the melting nor fire result from an electrical short. They result from excess heat that goes outside of the design specifications for these parts.

The terminals for the alternator charge harness are spade terminals. In the original design, when originally manufactured, they are adequate for their job, but have essentially zero margin to accommodate for the aging of these parts and the harsh environment they live in.

Engine vibration and thermal cycling (though a combination of heat normally present in the engine bay, as well as heat from carrying current) causes the spade terminals to lose their firm grip and become "wiggly". This loosened contact makes them get even hotter from trying to carry the same current, and the cycle repeats until they make quite poor contact and get quite hot, which causes the melting and eventual fire hazard.

If someone is hell-bent on keeping the car "unmodified", replacement of the alternator and charge connector should probably become a scheduled maintenance item, maybe yearly. Knee-jerk overreaction? Maybe, but no more senseless than the choice to keep the 2G. There is no viable way to monitor the condition of the connector, because disconnecting it to look at it will contribute to the problem developing. By the time it gets visibly melty, the actual problem has been brewing for a long time.

Additionally, regardless of the alternator on the car, driving a classic car carries some responsibilities over and above just driving some 2021 whatevermobile. The operator of the vehicle should have basic mechanical and electrical knowledge of the systems of the car, and the vehicle must always be equipped with a fire extinguisher that the operator is familiar with the location and use of. On a long drive, I carry two.

All common sense and logical statements but as originally mentioned it is not my car. If it were, it would already be converted to 3G! Even though the idea of maintaining it "original", in this case at least, is NOT a good idea we were still wondering how powerful of an alternator can be used with the OEM wiring.

[kishy]

All common sense and logical statements but as originally mentioned it is not my car. If it were, it would already be converted to 3G! Even though the idea of maintaining it "original", in this case at least, is NOT a good idea we were still wondering how powerful of an alternator can be used with the OEM wiring.

I am of the opinion that, if you were to chop the connector off and crimp (like the hydraulic type, not the scissor-looking crimper for small gauge wires) a decent thickness lug onto the two wires together, you could put a 3G on it (95A being the lowest-amp version I am aware of off the top of my head) and probably be fine because there is a fuse link in the original wiring, sized to the original wiring. The car is still only going to pull as much current as it needs, and if the loads are all unchanged, it seems to me the factory fuse link will still provide the required capacity.

Someone else may be able to offer a differing opinion and probably will, but the general rule is that just because more amps are available, does not mean more amps will flow.

What is unclear to me is whether there is maybe already enough load in the car to burn that fuse link, and the only reason it doesn't is because the alternator won't supply enough to burn it. Considering an example where every load in the car is turned on and maybe the battery is sucking up a couple amps because it was a little low to start...I'm really not sure if there's 65 amps worth of stuff in the car, but it seems to me there could be.

[friskyfrankie]

He has an aftermarket Alpine Head unit that runs through the Premium OEM system. That and A/C but nothing else exotic (like a high powered stereo system, big Sub, etc....). He says at night, he hears a slightly lower left or right signal but no pulsating of the lights with stereo, lights and A/C. This all with a 60 Amp alternator. I figured, with a 75 tops that might make him feel better without converting (even though I still would!).

[Arquemann]

He has an aftermarket Alpine Head unit that runs through the Premium OEM system. That and A/C but nothing else exotic (like a high powered stereo system, big Sub, etc....). He says at night, he hears a slightly lower left or right signal but no pulsating of the lights with stereo, lights and A/C. This all with a 60 Amp alternator. I figured, with a 75 tops that might make him feel better without converting (even though I still would!).

My 60A 1G is doing just fine with stereos, blower motor and lights on. High beams dim a little bit when I put on the indicator. And that only at idle or very low engine speeds.

[GM_Guy]

And what do the headlights do when you hit the brakes? Thats where you will often see a brief moment of dimming.

friskyfrankie, tell your friend that nobody is going to notice theres a 3G alternator in there. If hes got the stock 2G, the mustang small case 3G drops right in place (might have to do a pulley swap for the 2G pulley) and looks right at home in the engine bay. Adding a wire & fuse isn't going to be obvious, just wrap it with the black split loom and route it with a factory harness, blends right in.

[gadget73]

The low output at idle speed is a common issue on the 1G and 2G. Their output vs rpm curves are worse than the later alternators, and honestly if you're going to notice a change, at idle is where you will see it. Driving down the road you'll probably never know the difference unless you have something thats really gobbling a bunch of extra current or the alternator just isn't working correctly.

The old 1G works just fine and isn't unreliable. The idle output kind of sucks but its not that big of a problem. The Mark VII and Continental both run them and I have no plans to change it. Even have a spare on the shelf.

agree with what Kishy said above. They weren't engineered to catch on fire, its just not exactly engineered in a way that makes it unlikely to catch on fire either. The plug-in connection I'm sure is wonderful for rapid assembly on the line but its just not robust enough long term.

[friskyfrankie]

And what do the headlights do when you hit the brakes? Thats where you will often see a brief moment of dimming.

friskyfrankie, tell your friend that nobody is going to notice theres a 3G alternator in there. If hes got the stock 2G, the mustang small case 3G drops right in place (might have to do a pulley swap for the 2G pulley) and looks right at home in the engine bay. Adding a wire & fuse isn't going to be obvious, just wrap it with the black split loom and route it with a factory harness, blends right in.

Not sure on the dimming of headlights when braking but will ask. Don't think he is overly concerned about ascetics but I think his motivations fall into two categories - 1) If it ain't broke - don't fix it and 2) Since he can't do the job himself, he may not want to bother me or someone else. I have seen the conversions and yes, you can blend the job where it is not noticeable except to one who knows better. Wonder what year Mustang is an exact fit?

[Giraffe]

Not sure on the dimming of headlights when braking but will ask. Don't think he is overly concerned about ascetics but I think his motivations fall into two categories - 1) If it ain't broke - don't fix it and 2) Since he can't do the job himself, he may not want to bother me or someone else. I have seen the conversions and yes, you can blend the job where it is not noticeable except to one who knows better. Wonder what year Mustang is an exact fit?

1994-1995 5.0 and 1994-2000 3.8 Mustangs would have a suitable alternator. 2001-2004 V6 Mustangs used an upgraded 6G rated for 110 amps with an even smaller case than the 3G.

Agreed with everyone else on the recommendation of an upgrade. The problem with "if it ain't broke, don't fix it" in this case is that when it breaks, it may take the whole car with it.

[friskyfrankie]

1994-1995 5.0 and 1994-2000 3.8 Mustangs would have a suitable alternator. 2001-2004 V6 Mustangs used an upgraded 6G rated for 110 amps with an even smaller case than the 3G.

Agreed with everyone else on the recommendation of an upgrade. The problem with "if it ain't broke, don't fix it" in this case is that when it breaks, it may take the whole car with it.

Agree completely! Wonder which one of the two choices you mentioned is the better exact drop in fit?

[sly]

3G is easier due to same connector. 6G uses a different connector.

[gadget73]

also depends if you're shopping new or used. Less true now, but not so horribly long ago mid 90s cars were all over the junkyard and several had a compatible alternator. Find one that the hood wasn't open on and the alt didn't look like a crusty heap of crap and you could usually score a serviceable one for pretty small money. With a little more effort you could score the fuse and the charge cable as well. When an hour and 30 bucks will get you all you need it was hard to argue with.

[Kodachrome Wolf]

The 6G supposedly is a bit better at low speed charging even compared to the 3G, but both do well when replacing the old firetraps.

I've tossed 3Gs on five vehicles, including two non-Panther applications and they've worked great compared to their predecessors. I've personally installed a 6G on my '87 after the 3G gave up, but the 3G was a junkyard score as it went which had obviously been exposed to a lot, and it kept up from about late 2016 until 2021.

[GM_Guy]

Putting the 2G pulley on if it is larger than the 3G pulley will take care of any idle charge. I put the 2G pulley on my 3G so I could use the factory belt (one less thing to keep track of). It easily put out the rated 130amps at idle doing a load test.

Yeah, I suppose if you can't do it yourself it would factor in unless you got someone you really trust to do it, and not rape you on labour for what is an easy job.

[friskyfrankie]

I could do it for him but finding the time is the problem! Since I've known him since the 7th grade I would not even charge him so that is not an issue.