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View Full Version : Alternator upgrade...90 amp to 136 amp


ArizonaXJ
08-27-2007, 05:15 PM
OKay, here we go. I'm reinventing the wheel again but, WTH?

So, a few months ago I decided that I HAD to get more juice in the old Cherokee's electrical system.
Hundred watt off-road lights, winch, electric fan, etc. was starting to takes it toll. Now, I did some research here and on other websites about how to do this. The one thing that I wanted (needed to really) to stay away from was 1. A really expensive after market alternator and 2. An inexpensive but nightmare to wire up alternator.
That left me trying to find something within the Chrysler/Jeep/Dodge line up.

Well, I found it......

You can go to Autozone and get Part number 13387. It is a 136 amp alternator for a 97/98 ZJ (Grand Cherokee) with the 5.2 liter engine.
I am sure that Checker or any other parts store will have this but I am not sure what the part number will be.
The cost for this alternator is $149.99 + tax and a $90.00 core charge. They will accept your puny 90 amp as the core. This is the lifetime warranty one. Also, if you know of someone with a military I.D. card, take them with you. Checker and Autozone does give military discounts!!!:D

Now, as was stated in other alternator swaps along this line, the 136 amp one does have a slightly wider pulley. This is no problem to worry about. Just make sure that when you install the belt that you set is as far back on the pulley as possible. That 1-1.5 mm extra does not interfere with anything or even come close.

The wiring is straight forward. It goes on just your old 90 amp one. No differences.

The one and only catch to all of this and it was NOT mentioned in any of the articles that I read was the alternator mounting bracket itself. It is TOO SMALL to hold the 136 amp unit.

You will need to take an angle grinder to it so that it will fit around the 136 amp unit. What you will need to do is remove the entire bracket form the vehicle. Set one of the alternator bolts into the alternator and the bracket as if you were installing it in the vehicle. Once you do this, you will see how much material that you need to take off from the bracket. It will hit the side of the alternator's housing until you get enough material removed from it. When you have enough material removed, all of the bolts will line up and go in without hitting or binding anything. Once you have enough clearance for the 136 amp unit, bolt it in just like you would any other unit into the vehicle.

Now, I know there are other ways to approach this but this was by far the easiest and most economical way that I found.

Since I didn't take any pictures of my work when I did it. I made a couple of drawings to sort of aid in my explanation and attached as a word doc.

***One word of warning**** WHEN REMOVING MATERIAL FROM THE BRACKET, DO NOT, DO NOT TAKE ANY MORE OFF THEN NEEDED TO CLEAR THE NEW ALTERNATOR!!!! YOU ARE WEAKENING IT AS IS BUT NOT TO THE POINT OF REALLY HAVING TO WORRY ABOUT IT. REMOVING MORE MATERIAL THEN REQUIRED IS ASKING FOR BREAKAGE.

With all of this being said. I will gladly help anybody out with this project. It doesn't take too long to do. The big pain in the butt is gradually removing the material away from the bracket.

Tom Schenk
08-27-2007, 07:02 PM
I didn't have any mounting issues with mine. Did yours not have that slidy sleeve thing at the mount?

ArizonaXJ
08-27-2007, 07:44 PM
I had the thingy but I needed to remove material from the bracket due to the larger girth of the new 136 amp alternator.

GRUNT
08-27-2007, 07:57 PM
Hmmmm, does anyone know the differences in the brackets?
XJ had an XJ and had to cut it....
Tom has a.. WHich one did you use Tom? CJ or WJ?
I have a YJ myself and would be very interested in this!

Tom Schenk
08-28-2007, 01:17 AM
Mine was a TJ, but, I put one in a buddy's 2.5L YJ without modification apart from the black boot in the back.

YJunk
08-28-2007, 08:58 AM
I might give this a try this weekend... I've got some super bright light now that came with a warning "do not leave lights on if vehichle is at an idle"... thinking a bigger altenator is probably a good thing.

ecamp55
08-28-2007, 03:05 PM
Hmmmmmmm, I wonder what it would take to do this with my CJ????

Wayco
08-28-2007, 03:16 PM
So I guess that this will work on a TJ without modding the bracket, but a XJ needs a little grinding? I'm planning on adding a few lights, this might be a good mod. for Hyjak too.

AZG23
08-28-2007, 04:36 PM
Id look for a Jeep/Dodge FACTORY solution...I believe there was a minivan that had one that works...

Ive had real crappy luck with Checker/Autozone alternators....went thru 6 of them in one vehicle before giving up and getting a factory alternator and never had an issue after that. It worked perfectly until I sold it 2 years later.

...one Autozone alt went within a week...several within a few days. I even installed one and it instantly failed.....now this wasnt on a Jeep...but still...Ill never put another Checker/Autozone electrical part on any of my vehicles...

Just my 2 cents...would suck to get broke on the trail

Tom Schenk
08-29-2007, 12:34 AM
Hmmmmmmm, I wonder what it would take to do this with my CJ????

Careful...IIRC the CJ voltage is regulated at the alt. whereas the XJ, YJ, TJ voltage is regulated at the computer. Of course I may be completely wrong but maybe right too. I'd ask a guru before trying. :)

ademster
08-29-2007, 11:14 AM
I have a cj with a 89 XJ 4.0

would this work>?

Tom Schenk
08-29-2007, 11:41 AM
maybe? :)

GRUNT
08-29-2007, 11:49 PM
Cool, will be doing this with my YJ then. Thanks Tom, Semper Fi!

ecamp55
08-30-2007, 05:15 AM
Careful...IIRC the CJ voltage is regulated at the alt. whereas the XJ, YJ, TJ voltage is regulated at the computer. Of course I may be completely wrong but maybe right too. I'd ask a guru before trying. :)

You're right, I don't have a computer in my 74

ArizonaXJ
08-30-2007, 05:33 PM
The biggest difference to worry about aside from the slight size difference is the difference between internal and external voltage regulators. Unfortunately, I do not know what all is and what isn't internally regulated.

As for what was posted about Autozone/Checker parts vs. Dealer parts; I must say that I have had this problem before. However, that was on my 68 Mustang. No one, not Pep-boys, NAPA, Checker, Autozone, etc. carried a starter for 1968 Mustang with a 302 with C4 auto. They all listed the part number for a 302 with a standard tranny. I contacted the dealership for part number confirmation and then picked parts store's brains.....When I tried to tell them that the starter they were selling was incorrect for automatic they all said,"well, thats what the computer says it takes"......now you all know why I ask for the "oldest guy in the shop" when I go for parts or am experimenting.

All I can say is that the information that I gave you is accurate as I have, to include part number from Autozone. I verified alternator wiring, shape, color, pulley size, etc. before I tried to install it. As I said, everything went together just find except for that the 136 amp one cause me to have to "dish out" the alternator bracket a little. For what it is worth, I compared the wife's 89 XJ and our 05 TJ to my 92 XJ and I will be doing the same to both soon. Identical alternators except for size (girth).
This will probably wait though until I get back form "across the pond" in a few weeks.