I did the GM alt. swap about a year ago I think, and found the case size to be smaller than anticipated. The space between the ears of the alt. was much narrower than described in the write-up. I needed to grind about 3/8" off each ear, and it sounds like more people are running into this. It seems like some of the older 7157's I have seen in the yards had a larger case.

 

Has anyone bought a 100 amp GM 7157 somewhere recently that didn't require the major grind? Autozone apparently carries the smaller one. Or does anyone know why some alts with the same part # and application would be different sizes? What's the dealio? I would rather replace this one with one that matches the write-up instead of modifying my alt. bracket, and I am sure other members considering the swap would too.

 

Bump...so nothing huh? I guess it's a bracket mod. then. It will be more adaptable anyway.

Check out Summit. They have a 100 amper on sale right now for about 67 dollars + shipping. It's a part number 7157 large body, available in any color you want, as long as it's black!!!!

 

I only point it out because it's a pretty smoking deal, and it ends in late April.

Thanks 3eyedwagon. So there's a large body designation, I hadn't seen that before in my searches. That's what I was lookin' fer.

I just installed an alt out of an 83' Caddillac Brougham Elegance.

It appeared to be a 7157 although it seemed a bit big.

I looked it over for any stickers or part numbers and all I got was a

manufacturer number :-\

It is a large case alt rated to, I believe 80 amps.

I had to add another plate to my current bracket and shave off some of the

metal on the inside of the bracket to make it fit.

I'll post pics as soon as I remember to take them

 

Twitch

I had to take a ton off of my 100 amp GM alt as well. Must be a smaller case.

 

I'm thinking if it ever needs replacing I should be a good guy and NOT take it in for the core. That could really mess with some poor guy that gets it (if it makes it past the rebuilders) after me trying to put it in his pickup or something.

 

Scoobyclimbs did his after seeing mine and just fabbed up a new mount. He thought ahead about the core thing.

I'll proly do the same on the next one.

I did mine it took some grinding. spend the 8 dollars for a Habor freight 3 inch cut off tool. I bought mine off ebay for 49.99 shipped. I figured if it was junk that it would at least cover what I would have to pay for core.

you can see it mounted here.

 

 

I was even able to use the factory belt.

I will be doing this mod on my wagon some time in the future too.

Is this mod possible on a Forester?

I belive a mod would be necessary for a forester.

What year is your forester?

If you check at NAPA or CSK/O'Reilys or Autozone, they should be able to

get you a higher amp alternator that won't require any modifications.

Not to mention the forester has a serpentine belt, so you would have to do a

pulley swap on the alternator.

Just ask questions at your local parts store, they should be knowledgeable

enough about the new stuff, that they could get you a proper alternator.

 

Twitch

I'm OK with mods,really want something with more AMP's than stock.

Will check into it.

 

Thanks.

Just curious, has anyone tried the 1 wire GM internal alternator? It seems like it would be an easier swap without having to worry about all the rewiring or anything, and its about the same size..