mustangGT86_05

Pretty simple, I already figured out the pulleys can be swapped, so I am now wondering what 3g alt would have the threaded ear on it? from what I've read they can with and without a threaded ear on them. Also I did a little looking for my car and I guess mine has a 65 amp alt on it, so even putting the 75 on would be an improvement, but will the procedure be the same on the 86 as for the 87-93? I have under drives so I figured it'd be best to swap the alt on it.

oatburner99

well be careful with the pulley's, i had a stock 75 amp alt on my 90, picked up a 3g off a 94 T-bird v6 went to transfer the pulley from my stock alt over to the 3g, and it would not work. The pulley on the 3g has a built in spacer on the back to space it out towards the front of the car, in order to clear the main body. Fox style alt's don't have this, because the shaft is long and has a shoulder. I ended up using the pulley that came on the 3g alt, and just got a long belt to make up the difference. As far as the threaded part, i just put a bolt/washer/lockwasher/nut setup on mine, spent too much time trying to find a good working alternator that was threaaded. As far as putting a 87-93 alternator on your 86, yes it would be an improvement over your stock 65 amp. which i have a brand new alternator (75 amp) that I'm looking to sell. However, if you are looking at putting a efan on your 4 eye, or running electronics (stereo) i would advise that you do the 3g swap.
here's the write up that I did on my car:

Well this mod if finally done. Didn't take too many pictures. I read thread after thread about this mod. Some people said do it this way, other's said this way. This is how I did mine. Pretty straight foreward if you ask me.

Dirty Engine Bay


As some of you have read you MIGHT have to notch out your alternator bracket. I had to on mine. Took a die grinder and dremel to grind mine down a bit. I borrow the pictures from another thread so you can see what you need to do:
BEFORE

AFTER


The top bolt hole on the fox is threaded (3/8) if I remember correctly. With the 3g alternator, you can either put in a helicoil, or you can do what most people do and go get a 2in 3/8 bolt,lock washer and nut to bolt up the top of the alternator. The bottom mount retains the factory bolt


New 4gauge power wire going from the alternator to the start solenoid. Some threads were different than other's here. Some said put a waffle fuse, or a fusible link on your new hot wire going to the solenoid. Some said close to the alternator, some said close to the start solenoid. I chose to put it close to the alternator. Well after some looking around (2hrs) No-one around here had a fusible link. So I ended up putting a 140 Amp Circuit breaker in. 4gauge in, 4 gauge out. This way if something goes wrong and I blow a fuse I'm not paying $5 a fuse.

New 4 gauge wire:


Circuit Breaker:

Spliced Stator wire:

Belt Clearence:


That's pretty much it. Only other problem that I ran into was the pulley that was on my stock Fox 75 amp alternator was not the same size that was on my 3g alternator.My belt that I had wasn't big enough. So I ended up just changing out the belt.

This mod is leading up to this:
Taurus Fan

primetime5.0

I use a 2g pulley on my 3g alternator without any issues.

mustangGT86_05

What did you pull yours from primetime? I was reading a seperate write on it last night that a guy used from a 94-95 5.0 and said pulleys could be swapped. He also mentioned that the pulley size appeared equivalant to the underdrive kit, still just in case I would like to make sure I could swap them.

Thanks for the info oatburner, I am for sure going to convert to an electric fan, and already have a better sound system. Now im wondering also, that circuit breaker would allow you to cut feed to the alt, correct? Just wondering because I could see that being a plus in the drag racing world

primetime5.0

I bought an alternator from a 95 mustang

Justin Burgess

the 3g upgrade is a easy fix. got my alt out of a 94/95 mustang. Youll have 2 power lines coming from your old alt, their spliced into one line.cut that line back till you only have 1 wire, then cut the alt bracket so the 3g will fit, angle grinder is what i used. splice in your new line, bolt it up, and your done. took me about a hour for the whole job. i also have underdrives on mine and have had no problems with bigger pulley on it.

stdyhand

I did my 3g and it works fine, but for some reason my stock voltage gauge doesn't always work. I start the car and it runs fine but I can drive down the road and the the voltage will just suddenly start working. I never had this problem until after I started using the 3G.

projectresto83

If you are asking what could be the cause then post your own thread in the tech section..

stdyhand

No it was a statement, not a question.

projectresto83

Just sayin....don't need newbies highjacking threads....