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100 Amp Alternator in '89 XJ?

The alternator will only generate the current the system actually requires (that's what the regulator is for,) but you should upgrade the mains leads and fusible link. If you were going past 100A, I'd say you definitely want to upgrade the mains leads and fusible link, but AMC was a little more generous with their wiring than Chrysler.

(This is coming from someone who has an alternator tested for 198A running in his 1988...)
 
there is a 120 amp alternator that was a factory option for the xj. i just installed one. it actually tests out to 132 amps. i bought it rebuilt off ebay w/ 1 yr warranty for $60. works great and it bolts right in. autozone sells them also for $150.
 
jeepster_259 said:
there is a 120 amp alternator that was a factory option for the xj. i just installed one. it actually tests out to 132 amps. i bought it rebuilt off ebay w/ 1 yr warranty for $60. works great and it bolts right in. autozone sells them also for $150.
Click to expand...

What year? Alternator manufacturer and style changed for 1990/1991...

1984-1986 used the Delco 12SI internally-regulated unit
1987-1990 was the Delco CS130 internally-regulated.
1991-2001 was the Nippondenso externally-regulated, up to 117A OEM (up to 136A can be made to fit, but the frame size is larger.)
 
Sweetness, i wish the cherokee's alternator was up high instead of down low im sure ill be replacing those quite often. Is there anyway to weather proof my alt from the elements IE mud, deep water, clay, etc.

-PJ-
 
vortex said:
Sweetness, i wish the cherokee's alternator was up high instead of down low im sure ill be replacing those quite often. Is there anyway to weather proof my alt from the elements IE mud, deep water, clay, etc.

-PJ-
Click to expand...

if you dont have or want AC, you can move the alt up to the spot where the condensor is.
 
jeepster_259 said:
i'm not sure what years the 120A was an option for, but it is a nippondenso alternator. go to autozones website and u'll find it.
Click to expand...

Exactly. Meaning it is not a "drop-in" upgrade.

Since there are plenty of upwound CS-130s available, they're easy enough to find.
 
jeepster_259 said:
it is a drop in upgrade for the 120A alternator. it was a factory option. fits w/o any mods.
Click to expand...

To upgrade the ND used 1991-up, yes. For the Delco used 1990 and earlier, no for both of them. If you can fit the 120A ND in place of either Delco (which I'm not arguing - I've not tried,) you still have to make an electrical mod to add the regulator you've removed with the Delco alternator.
 
vortex said:
Sweetness, i wish the cherokee's alternator was up high instead of down low im sure ill be replacing those quite often. Is there anyway to weather proof my alt from the elements IE mud, deep water, clay, etc.

-PJ-
Click to expand...


Here's a hint: If want/don't mind switching to two electric fans, go pick up YJ/TJ/XJ 2.5L alternator/condensor brackets. They'll relocate your alt. RIGHT below the condensor, no extra pulley for the mechanical fan, though, so you'll need to swap to dual electrics.

This works for both renix and HO engines, just make sure you get the brackets from a jeep close in age to yours.

I seem to remember that by going this route, you CAN switch to a ND externally regulated unit on the renix, I think you just have to pull the regulator from a JY wiring harness...

Didn't Chevy's use delco alternators? Just externally regulated?

Just looked at the guy above me's post, hadn't seen that one before... but it doesn't address RENIX brackets as far as I see. Good news though; the 2.5TBI brackets work the same!
 
Last edited:
Mr_Random said:
Here's a hint: If want/don't mind switching to two electric fans, go pick up YJ/TJ/XJ 2.5L alternator/condensor brackets. They'll relocate your alt. RIGHT below the condensor, no extra pulley for the mechanical fan, though, so you'll need to swap to dual electrics.

This works for both renix and HO engines, just make sure you get the brackets from a jeep close in age to yours.

I seem to remember that by going this route, you CAN switch to a ND externally regulated unit on the renix, I think you just have to pull the regulator from a JY wiring harness...

Didn't Chevy's use delco alternators? Just externally regulated?

Just looked at the guy above me's post, hadn't seen that one before... but it doesn't address RENIX brackets as far as I see. Good news though; the 2.5TBI brackets work the same!
Click to expand...

Delco-Remy is essentially a GM brand, but AMC used an awful lot of them (as do hotrodders - it's fairly easy to convert a Delco CS or SI to a "one-wire" setup, and that takes care of that. The regulator is still internal, it just has the sense lead internal to the alternator instead of needing it hooked up from somewhere outside the case.)

It's very common to swap Delco alternators into just about anything - they're pretty robust, and tend to be compact for their output. I've seen them on a lot of industrial equipment as well.

A nice thing about Delcos is that all of the units with a common "frame" or "armature" size use the same internals, with the only real differences being the pully, the mounting ears on the case, and the "clocking" of the rear case (location of the regulator plug relative to the mounting ears.) It's easy to reclock a Delco case - takes about two minutes. Swapping pullys takes about two minutes with an impact, or five without. And, you can always swap in higher-output internals to increase output.

Finding CS130 internals set up to give 140A or so isn't a problem - and, if you don't feel up to it, a shop can do them for you all day long. Going higher takes a bit of doing, but it can be done.

There are two main series of Delco internally-regulated alternators - the SI series (older flat regulator plug w/two 1/4" spade lugs) used until the mid-1980s, and the newer CS series (four-prong Weatherpack regulator plug.) The CS series is being replaced by the AD series - essentially an improved CS, I believe - but I think there are still some CS units making it onto production vehicles. The two-digit number preceding the SI (e.g. 12SI) and three-digit number suffixed to the CS or AD (CS130 or AD244) refers to the physical size of the armature, with higher numbers being physically larger. I know that the CS series is sized in millimetres (CS-130 being a 130m/m OD armature,) but I don't recall how the other two work offhand.
 
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