Full Size Jeep Network

I'm having one hell of a time here trying to get the alternator to fit. It looks like the previous owner tried to do something to make another alternator fit, or not sure what's going on.

The two alternators I tried from parts stores that said they were exact matches, did not fit.

After doing some digging, I found that the alternator that is in the jeep now is a Delco-Remy 15SI rated at 105A- I don't think that was stock.
The problem is when I tried to fit in the other 10SI units the hole wouldn't line up with the adjustment bracket.

Some pictures:

First off, is the the stock bracket?




Here's what it looks like installed:








And here are the two alternators side by side:



Here's the fitment I'm having trouble with:



Here it fits the 15SI fine:

stock alternator for an 82 i believe was either 63 or 75 amps. I beliee it was 63

Later Grand wagoneers 86+ like my 90 stock was actually 90Amps. As for brackets i dunno sorry cant help on that one.

I'd look for a shop to rebuild the 15si. Not sure where you are but there used to be a shop on Valmont, just outside Boulder. Or, you could always rebuild it yourself. I've heard that's possible, anyway.

KJ Ryu wrote:I'd look for a shop to rebuild the 15si. Not sure where you are but there used to be a shop on Valmont, just outside Boulder. Or, you could always rebuild it yourself. I've heard that's possible, anyway.

+1. Be sure to remove or disable the ammeter if you use a larger-than-stock alternator. The ammeter wiring is dicey after 35 years, even with the stock alternator. You don't want a dash fire. I'd also say that the 10 ga charge wire through the bulkhead connector (!) and back is seriously undersized for a 100A alternator.

What's wrong with this alternator; ie why do you want to replace it? These GM modular alternators are very easy to rebuild. You can get a kit on eBay, or pick the individual parts from RockAuto or your parts store. To refresh the electronics, replace the brushes, regulator, diode trio, and rectifier bridge. You can slso replace the ebarings if you wish. Few rebuild them because the complete alternator is so cheap from the McParts store.

Ammeter has been bypassed, and when I put the/a new alternator in, I am adding a lead from alternator output to starter solenoid.

Is the alternator and bracket setup I have a stock unit? All parts stores say 10SI and I've never even heard of the 15si before this one.
I'm also asking because the alternator does not line up exactly with the crank and water pump pulley - it's a bit angled. So I'm not sure if PO messed with setup to try and fit an alternator he had lying around in there.

I don't think I'll be rebuilding this one, maybe one day as a fun project, but it's just not appealing right now when I can buy a new alternator for $40.

My '82 has a 10SI. I don't think the 12SI or 15SI even existed in that era.

If I remember, I'll take a look under the hood of my truck tomorrow when it's light.

Is it possible to put a spacer behind the bracket on the motor end and mount to the other side of the tab on the alternator? The bracket "looks" right but is obviously too large... maybe... I have two "mostly stock 360s in my garage. One has a bracket very much like yours. The other looks like the one you need.

Yea mine on my 90 looks like one in your first pic

Thanks for the pics!
That's reassuring for me, I guess I have "a" stock alternator bracket then, maybe not stock to my vehicle, but stock from a later model grand wagoneer. I looked up parts for a 90 GW FSJ and some catalogs list a 15SI as an option (15SI has a 150 mm case opposed to 140mm for the 10 and 12 si).
My bracket looks very similar with those ears at the end and the same little divot/kink too. I'm never sure anymore with this vehicle and can't trust anything the PO did, and I don't have another vehicle to reference and don't have prior knowledge like I do with the 4.0L.

I'll be looking for a 9:00 15SI alternator then, or maybe I will do some rebuilding of my own.

It's also easy to clock these modular GM alternators. Just use a toothpick to hold the brushes back (there is a hole in the case for this), and you can clock to whatever rotation you want.

montanablueSJ wrote:Thanks for the pics!
That's reassuring for me, I guess I have "a" stock alternator bracket then, maybe not stock to my vehicle, but stock from a later model grand wagoneer. I looked up parts for a 90 GW FSJ and some catalogs list a 15SI as an option (15SI has a 150 mm case opposed to 140mm for the 10 and 12 si).
My bracket looks very similar with those ears at the end and the same little divot/kink too. I'm never sure anymore with this vehicle and can't trust anything the PO did, and I don't have another vehicle to reference and don't have prior knowledge like I do with the 4.0L.

I'll be looking for a 9:00 15SI alternator then, or maybe I will do some rebuilding of my own.

Just make the bracket bigger man.. Get a drill bit and open the bracket bigger to fit the bolt .. Thats what id do.. Like 95% confident itd work itll just take time to make the whole thing bigger

I'm 95% confident that ^^^ will result in a trip to the ER to separate metal from human. Die grinder or dremel would be a better tool for that job.

KJ Ryu wrote:I'm 95% confident that ^^^ will result in a trip to the ER to separate metal from human. Die grinder or dremel would be a better tool for that job.

Well if you have a table clamp or vice it wouldnt lol but yes dremel if you want lol. Same thing though just make the bracket openeing bigger to fit the alternator bolt