GT6 alternator rewire

[tamagotchi]

Hello all

I have been searching through the various pages for some guidance on changing the current ACR15 alternator to the ACR16 alternator and the associated rewiring it needs. I've checked out Rick Astley's book on the subject but cant seem to work out which wires I should be doing away with to get it down to three wires from five, and don't want to risk taking out the wrong ones! Any ideas which i should do away with? See pic of wiring in situ..

Thanks!

[SpitNoir]

Down to a more normal 3-wire alt then, eh? Sounds much simpler.
Like you, I've looked for details on various alternator conversions too, but don't remember seeing good pictures of the back and descriptions of the connections. So I'm not sure what all the 6 existing wires do, but what the heck. Let's play.
Just for conversation's sake then, let's find out what each one is. I am by no means an experienced ACR oficianado, so please take this as rambling garage-talk for now. Just to kill time until someone with real knowledge has the time to chime in.

Looks to me like the alternator's case and connectors are clearly marked as to their basic battery functions, so let's test. If you have a volt-meter or light to just verify, I'll venture a guess as to their function.

First, the 2-wire plug in the lower portion of your image:
The large Natural/Brown/Tan (whatever it's called) wire looks to be your alternator's main output wire. If so, it should test with full battery voltage all the time.
That wire is going to be kept of course, and go to the output stud or terminal of the new alternator. It's currently marked with a "+" and is the larger wire, so that's a reasonable "assumption" here.

The Black wire in the same connector should be the system ground. You can verify with an ohm-meter, or volt-meter if you put the red test lead to the battery's positive side.
This wire is very possibly one that might no longer share a space in a common connector. Could have it's own ground terminal on the new alt, so that would be one of the wires that would not be counted in a 3-wire setup. Commonly alternators are grounded through their cases and mounting bolts. I personally feel it's just good sound practice to have a dedicated grounding wire or strap between the case/bolt/stud to a good ground. Whether directly to the battery, or just to a well-known grounded area of the engine or chassis.
Oops, got ahead of myself. Substitute "earth" every time I mentioned ground.

The 3-wire plug:

The top wire is also marked "B+" so may be the sensing wire. It should also test out as always hot with battery voltage.
This wire will probably have a home in the new alternator too. Also, a way to verify that the system is sound is to measure voltage with a good meter and make sure there is no drop between the battery and that wire. More than say, 1/4 volt and you should start looking for corroded connections or old tired wire. You want this to read as close to battery voltage as possible, or the alternator could try to overcharge the battery.

Are the others marked? One of the other two connecting points should be an ON with the key 12v source. Easy to test too, with your light or meter.
Not sure if this is needed on the new one or not. Some alternators have "self-exciting" regulators and don't need the keyed-power.

Not sure what the other one(s) would be, unless the regulator has it's own discreet earth connection, or they do the same duties as some of the additional wires on the old external regulator/control boxes from the generator days. Because they're not Black though, perhaps they send a signal to an indicator lamp in the dash, or a Stator's output voltage for a heated choke for the carbs, or whatnot.

Ok, so none of that may hold water, but I was bored and needed some chat time and was curious if I could figure out something I know nothing about. Kind of a crossword puzzle for car-junkies! Now maybe others can come play and give you corrected info in a less confusing format.
I'm very interested in hearing just how this setup is wired, and how well they work. Too bad I don't get e-mail notifications when someone posts a reply to a thread I'm in.

Good luck.

Paul

[Falkon]

Here this thread explains it after you wade through it. You're going from a 5 wire to a 3 wire.  
http://www.triumphexperience.com/phorum/read.php?8,734714,734714#msg-734714re.

[EddieGT]

Hi,

this is a good site too:

http://www.vtr.org/maintain/alternator/gm-spgte.shtml

lots more tips and tricks !

cheers, edwin

[jaybee]

I assume your 3-wire alternator will have connections as follows:
1 - main output wire (charging)
2 - to ignition warning lamp
3 - voltage sensing wire, going to battery positive terminal

Your main output wire is the fat brown (connected to '+' in your photo)
Check your remaining wiring to see which colour wire goes to your ignition warning lamp, and which goes to the battery. Wire them accordingly. Insulate the remaining wires, and you are finished!