WantACherokee

I think the alt in my '91 Laredo has a bad bearing... I have been doing some searching trying to see if an upgrade is available and it looks like a I can use a 136 amp alt from a ZJ with the 5.2L V8. Is this correct? What needs to be done to make it work? I've read some grinding on the bracket may be needed, that is not a big deal but I am more concerned with the wiring. I assume it should be upgraded to handle the additional output.

As far as I can tell from a quick glance it looks like the XJ alt just uses ring terminals on the power wires, should be pretty easy to get some 4 gauge cable and replace those with? I haven't pulled the positive cable to see where it leads, so I hope whatever it connects to on the chassis side is also a ring terminal or something that will allow it to be easily replaced?

93gc40

The ZJ alternator will work. You will need to lightly grind the mounts on the Alt and you might have to swap over the connectors.

WantACherokee

Cool, sounds like it should be an easy and worthwhile mod.

5-90

The ZJ/WJ/Durango alternator will indeed work - and you need to modify the mounting as noted.

Note that only the first couple of years used the M4 studs for the field coil terminii, later alternators used a two-wire plug (I'm working on a source for that as a conversion part.)

The mains wiring is easy enough - you'll also need a fuse kit for the alternator output lead (it's fused from the factory.) Click the link in my sig, I make kits that have been well-received.

jronald

For the 93 Grand 5.2lt
http://www.excelauto.com/
Offers a drop in replacement at 130 amps.

Ron

WantACherokee

Can someone tell me what exactly needs to be done as far as the wiring though? Won't I need to upgrade that since the larger alt puts out more power? I upgraded the alt in my Mustang and I had to run a larger power wire direct to the battery. Maybe someone has done a writeup on the XJ alternator upgrade?

freegdr

google has write ups on it every where

5-90

Upgrading the alternator itself is generally simple - as long as the connexions on the back are the same (later ND units used a two-cavity plug instead of the two M4 studs,) you will probably just need to grind the mounting area to make it fit. (The higher-output alternator usually has a larger frame size, all you need is enough room for the alternator plus a sheet of paper - about 1/4" usually serves. DO NOT GRIND THE ALTERNATOR CASE.)

Wiring? Click the link in my sig, I can help you with that.

WantACherokee

So I've been searching Google for over an hour now and also read your site 5-90, I see you sell some awesome battery cables, but I still haven't found a clear answer to my question. I understand the wiring needs to be upgraded... but what I still don't know is how, as in where to connect the larger positive wire I know I'll need, and whether or not to reconnect the factory wiring.

When I upgraded the alt in my Mustang I simply ran a 4 gauge wire from the alt + terminal to the battery + terminal (with an appropriately sized fuse in line of course), and left the tiny factory positive wire unconnected. Very simple. Can I do the same in my XJ?

When trying to trace the main positive lead on my XJ's alternator it very quickly disappears into a wire loom and I do not know where it ends.

5-90

Most of the leads will sort themselves out when you see them. The headache will be the alternator output lead.

The new lead will run to the PDC via a fuse block (you do want to put a fuse in - that circuit is fused from the factory...) but it can be difficult to figure out what's going on. The moulded rubber block on the back of the alternator isn't a bit help - so let me clarify things a bit:

- The B+ output stud on the alternator is the one with the black surround - usually has a "fence" around it. The two terminals with the common grey plastic surround are for the field coils. You don't want to mess with these.

- The B+ lead gets cut from the moulded rubber block. Cut it flush (as much as possible) and seal the cut end with something (I suggest the use of Plasti-Dip or similar, applied with an acid brush. You want to seal off the cut wire so you don't get corrosion in anything.)

- You mount the fuse block somewhere convenient (usually the fenderwell at the battery,) the lead from the B+ post on the alternator runs to it. The other side of the fuse would run to the PDC stud where the battery cable attaches, which will be fine. (For OBD-II vehicles, you have an additional stud on the PDC where the alternator lead goes, this can be determined by the one that has the smaller-gage wire on it. The fusible link is 10AWG, the B+ lead is 6AWG. You can run the fuse output to either stud at that point.)

- If you have the OBD-I PDC with the pair of MAXI fuses labelled "Generator," you can remove these after you've installed the new lead and fuse kit. In fact, I recommend it - this will de-energise the small Buss bar that the alternator connects to in that case (it comes up through a funky quick-connect lead into the bottom of the PDC instead of to a stud. Once you've fused the new lead, you can run it to the stud on the front - electrically speaking, it's the same connexion.)

Make sense now?