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Unread 04-21-2010, 09:15 PM   #1
TheNewbie
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Alternator upgrade question???

I'm going to be replacing my alternator in the morning. I've read a few threads in the past about a bolt in alternator that can pull more amps. After some searching I found this:
BC4x4.COM four wheel drive, 4x4, offroad and fourwheeling site.


I can get one of these alternators that pulls 136 amps for $149 or the OEM 90amp replacement for $115.

Has anyone done this? Will this fit my 95 2.5? And do I really only have to move over the rubber boot from the old alternator and shift the spacer bushing with some pliers and bolt it right in?

The part number that I called about is 56027913, which I got from that link.


And as always, thanks in advance!

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Unread 04-21-2010, 10:07 PM   #2
sentinal02
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Quote:
Originally Posted by TheNewbie View Post
I'm going to be replacing my alternator in the morning. I've read a few threads in the past about a bolt in alternator that can pull more amps. After some searching I found this:
BC4x4.COM four wheel drive, 4x4, offroad and fourwheeling site.


I can get one of these alternators that pulls 136 amps for $149 or the OEM 90amp replacement for $115.

Has anyone done this? Will this fit my 95 2.5? And do I really only have to move over the rubber boot from the old alternator and shift the spacer bushing with some pliers and bolt it right in?

The part number that I called about is 56027913, which I got from that link.


And as always, thanks in advance!
the other part that's left out in their write up is upgrading your charging wires to accommodate the increased amperage. the stock wiring i believe is 6 ga and is barely adequate for the 90 amp alt. while upgrading the alt by itself won't cause your stock wiring to draw more amperage than it already is, adding things to the jeep like extra lighting, a winch and an amp can all push the amp output of the alt to its maximum. if you try and funnel those extra amps through the stock wiring you'll at the very least blow the two 50 amp maxi's in the PDC and at worst could melt some wires. what you need to do is to upgrade the alt to battery connection somehow (there are a couple different ways to do this) so that it can handle the max output of your upgraded alt. but as far as bolting the 136 version to your 2.5L, it really is pretty much that simple.
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Unread 04-21-2010, 10:28 PM   #3
JeepinInFl
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I'm fixing to do this upgrade also. As far as the wiring goes, the + terminal has 2 cables, one goes to the starter and one goes to the fuse box, then from there to the alternator. Can you bypass the fuse box cable and run it straight from the battery to the alternator with a inline fuse. If so what size fuse ? I am going to use 4ga cable. Also should the ground be upgraded also ? Thanks
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Unread 04-21-2010, 11:00 PM   #4
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Originally Posted by sentinal02 View Post
the other part that's left out in their write up is upgrading your charging wires to accommodate the increased amperage. the stock wiring i believe is 6 ga and is barely adequate for the 90 amp alt. while upgrading the alt by itself won't cause your stock wiring to draw more amperage than it already is, adding things to the jeep like extra lighting, a winch and an amp can all push the amp output of the alt to its maximum. if you try and funnel those extra amps through the stock wiring you'll at the very least blow the two 50 amp maxi's in the PDC and at worst could melt some wires. what you need to do is to upgrade the alt to battery connection somehow (there are a couple different ways to do this) so that it can handle the max output of your upgraded alt. but as far as bolting the 136 version to your 2.5L, it really is pretty much that simple.
I was also looking to do this upgrade in the some-what-near future and was wondering if you could elaborate on this? Are there any cheap (i.e. junkyard) parts that could be adapted, such as maybe out of one of the compatible vehicles?

Thanks,
Mike

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Unread 04-21-2010, 11:09 PM   #5
sentinal02
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Originally Posted by JeepinInFl View Post
I'm fixing to do this upgrade also. As far as the wiring goes, the + terminal has 2 cables, one goes to the starter and one goes to the fuse box, then from there to the alternator. Can you bypass the fuse box cable and run it straight from the battery to the alternator with a inline fuse. If so what size fuse ? I am going to use 4ga cable. Also should the ground be upgraded also ? Thanks
yes, on pretty much all counts. my setup routes the alt's output directly to the battery + terminal via a 150 amp ANL fuse like this one:

StreetWires ANL Fuses Hi-Amp fuses (4 sizes available) at Crutchfield.com

from there, the stock wiring to the PDC powers the main bus just fine and any additional wiring i add gets wired directly to the positive terminal (I may add another fuse block later on). you'll just need to redo the positive cable clamp to accept the new heavy gage wire from the alt, along with the PDC feed and the starter cable. worst case, use a short length of 4 ga off the clamp and terminate all 4 cables with cable lugs (essentially big ring terminals) and then join them all with a single bolt. pack with dielectric grease, tighten it down good, and wrap with electrical and then friction tape (or liquid tape if you prefer. i like the friction as it's less mess).

definitely upgrade the ground cable as well since unless you wire all your additional components to the neg terminal directly, that current will pass through the ground cable too.
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Posi-Loked. Herculined. Optima yellow top. 1" Shackle, 2" BDS. Cragar 397's Aussie front.

92 YJ 4.0L Ax-15 231
5" springs, 1" shackle 31's or 35's depending on my mood
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Unread 04-21-2010, 11:21 PM   #6
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OP - your 1995 YJ will have the Nippondenso alternator. If you pillage around here, you should be able to find a "potential donor list" (Status: UNVERIFIED. Be sure to compare with OEM!) that will allow you to find possible parts up to 160A.

And yes, and especially if you plan to make effective use of your uprated alterantor, a wiring upgrade is essential. Bear in mind that OEM wiring is "just enough" for OEM parts, and is typically designed around a 40% or so duty cycle at full alternator output. If you're going to significantly increase the output (your 1995YJ 242ci should have either a 78A [std] or 90A [opt] alternator) and you want to make use of that increased output more than, say, 20-25% of the time, larger wiring is a must. That, and the OEM circuit protection just won't be enough to run the full output through - so that needs to be uprated as well (and fusible links are such a pain to deal with...)

AMC spec'd a 6AWG for mains. ChryCo used 8AWG (slightly smaller) instead. One thing I did like about AMC - they tended to overbuild...

I can help you with your wiring upgrade - but I'll need measurements (no-one's ordered for a YJ yet, so I don't know how long to make which wires, or what rings go on the ends.)

Identifiable Mains:
- Battery to Starter Motor
- Battery to Power Distribution Centre
- Battery to Engine Block
- Battery to Chassis
- Alternator to Power Distribution Centres (either up through the bottom and by way of two MAXI50 fuses, or by way of a section of fusible link wire to an M8 stud on the PDC.)
and you may have:
- Battery or Engine Block to Frame
- Engine assembly to chassis (common on the XJ and MJ.)

When upgrading the ND alternator, you may run into the frame size on the new alternator being a bit larger than on the unit you're replacing. Easy - just grind away the mounting slightly so that you can get the alternator in. You don't need to get much clearance, if you can slip a bit of paper in, you're good (the usual test I advise is a bookmark - it's light cardstock, so it's stiff enough to handle, but it's light cardstock, so it's not too large of a gage. I think bookmarks are about .015-.020" thick, which is plenty.)

Select the fuse according to the alternator you're going to use - if you're in between ratings, take the very next rating higher. For instance, if you mount a 136A unit in place, you'll be between ratings for the ANL fuses (..., 125A, 130A, 150A, ...) so you'll use the 150A.

If you get your alternator from a proper shop (one that does rewinds,) have them throw it on the bench and check actual max output - it can vary by as much as -5/+10% from rated (your 136A piece would have an actual max output of 129.2-149.6A.) The 150A fuse will still cover you, and it's easier to find a 150 than a 140 (I've seen ANL140 fuses, but they're scarce.)

I know ChryCo decided to run a pair of MAXI fuses in parallel inside the earlier PDC, but I can't help but think that this is a stupid idea. Something about it just rubs me the wrong way - a fuse, properly, should be a bottleneck for current. It's a safety device! Therefore, there should only be one of them in a given place in the circuit, not two that think they're one. This is why I use ANL fuses instead - that, and I can get them in ratings 60-600A (gets a little dicey and fairly spendy to find them past 300-350A, tho... 200A and down can be done in my sleep.) However, I do not and cannot recommend that the OEM circuit protection be simply eliminated. Every vehicle I've worked on (which means vehicles made back to about 1950 or so) has had some variety of fuse protection in the alternator/generator output circuit - and it's typically been a section of fusible link wire (using actual fuses thee is a fairly recent idea.) We have to assume that Engineering won that argument with Accounting for a reason - whether or not Legal helped Engineering (engineers and beancounters are always at loggerheads - it's amazing the number of purely stupid engineering and design decisions come out of accounting.)

Oh - the thumb rule for return cables is "Same size as the supply cable or one size higher. NEVER SMALLER."
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Unread 04-21-2010, 11:36 PM   #7
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Thanks everyone! Sounds good.

I have been reading about upgrading my wiring system, but haven't decided which method to use yet. But I don't plan on actually increasing my load yet. SO I think I can wait until I have an increased load. But towards the end of the summer I hope to have some aux. lights and a winch. So since my alternator went out I'll just upgrade now.


5-90, when you say "return cables" do you mean the ground?
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Unread 04-22-2010, 06:05 PM   #8
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Well, I got the new 136 amp alternator in there this morning. It was just as easy as changing the alternator to an OEM replacement. I read about having to change the rubber boot on the back of the alternator to the origional one that goes in the propper direction, but the back of this alternator and the mounting points were identical to what I had in there already. The only differences were the size of the housing and the pulley.

The housing was maybe 10% larger, but bolted in just fine, and the pully on the OEM alternator had 6 grooves and the new one had 7. But I put the belt in the 6 grooves closest to the alternator and it lines up perfectly.

I could tell that there was a lot more resistence on the engine when I first drove it, but once the battery got charged up it was running the same as always.


Thanks again for answering all my noob questions!
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1995 YJ 2.5 - 4” RC lift - 1" MML - 33's - flat fenders front - TJ flares rear -Raptor lined exterior - Herc'd interior - DIY front bumper & winch plate - 136 amp alternator mod - 4.0 TB swap

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I've got a shotgun, a rifle and a four wheel drive...
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Unread 04-22-2010, 07:00 PM   #9
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Quote:
Originally Posted by TheNewbie View Post
Thanks everyone! Sounds good.

I have been reading about upgrading my wiring system, but haven't decided which method to use yet. But I don't plan on actually increasing my load yet. SO I think I can wait until I have an increased load. But towards the end of the summer I hope to have some aux. lights and a winch. So since my alternator went out I'll just upgrade now.


5-90, when you say "return cables" do you mean the ground?
Correct. Electrically speaking, there's a difference between "return" and "ground" - "return" is the "cold" side of the power source (battery, generator, whatever) and "ground" (A/K/A "earth") is a safety lead back to the chassis or earth ground, and a chassis ground isn't necessarily a return.

Take a power tool for instance - if it's got a three-prong plug, it has "hot" (sometimes "phase",) "return" (sometimes "cold" or "phase return",) and "ground" (sometimes "earth") leads.

The hot and return leads are what powers the motor in the tool, and are sometimes connected using a rheostat for a speed control. The earth lead will be connected to the tool case - since earth is invariably a "zero potential" lead, you're not going to get shocked by it. Since the earth conductor (in a properly-wired system) is going to have considerably less reisistance than you, a wiring fault to the chassis will be bled off to earth via the wire - instead of via you.

Every electrical wire can be reduced to "hot," "return," or "earth," - there are just variations on "hot" leads: "switched hot," "modified hot," "variable hot," and the like (if it's run through a sensor, a switch, a relay, there are various triggers in parallel, ...)

I shan't go into colour-coding, since that's a whole treatise on its own!

In an automotive context, "ground" and "return" are effectively interchangeable terms - but automotive electrics is far from the only electrical work I've ever done, and sometimes the language slips across.
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Unread 04-22-2010, 07:33 PM   #10
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Newbie did ya do you upgrade the cables also ?
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Unread 04-22-2010, 09:14 PM   #11
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Originally Posted by JeepinInFl View Post
Newbie did ya do you upgrade the cables also ?
Not yet since I don't actually have any additional electrical draw (yet). I did this since I plan on adding a winch and getting some nice off road lights soon, and since I had to replace it anyway i figured why not spend the extra $30 now instead of replacing the whole thing downthe road.

I'll probably upgrade the wiring in the next couple weeks. But since there's no way I'll draw more than 90 amps with everything running all at once I think I can go 2 weeks.

But please correct me if I'm wrong.
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Unread 04-22-2010, 11:59 PM   #12
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I think you'll be ok. I'm doing the upgrade tomorrow and have a few accessories so I'm doing the cable also. Going to go with 4ga and lugs plus one 150a anl inline fuse.
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Unread 04-23-2010, 10:25 AM   #13
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Picked my 136 amp, slightly used, alternator up this morning. I'm running all new cable, custom built 1/0 welding cable, crimped lugs along with some 6 AWG. all new grounds, etc. I was only changing my valve cover gasket but I read this thread and got inspired. Might as well freshen up the starter while I,m in there I guess.
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Unread 04-23-2010, 01:31 PM   #14
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Originally Posted by TheNewbie View Post
But please correct me if I'm wrong.
you should be ok, but watch out if you drain the battery down somehow and then start the jeep. the voltage reg will see the dead battery as a drain on the system and push the alt to full output to compensate. your maxi's should blow before you toast the wires (that's what they're there for) but if you start blowing fuses all of a sudden that could be why.
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RIP: '88 YJ 2.5L Ax-5 NP231
Posi-Loked. Herculined. Optima yellow top. 1" Shackle, 2" BDS. Cragar 397's Aussie front.

92 YJ 4.0L Ax-15 231
5" springs, 1" shackle 31's or 35's depending on my mood
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Unread 04-23-2010, 01:33 PM   #15
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Originally Posted by QuantumYJ View Post
Picked my 136 amp, slightly used, alternator up this morning. I'm running all new cable, custom built 1/0 welding cable, crimped lugs along with some 6 AWG. all new grounds, etc. I was only changing my valve cover gasket but I read this thread and got inspired. Might as well freshen up the starter while I,m in there I guess.
1/0 is a bit of overkill for a 136 amps, but it can't hurt anything if you've got access to it cheap. i custom built mine from 2 ga on my 88 and never had any trouble with it.
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RIP: '88 YJ 2.5L Ax-5 NP231
Posi-Loked. Herculined. Optima yellow top. 1" Shackle, 2" BDS. Cragar 397's Aussie front.

92 YJ 4.0L Ax-15 231
5" springs, 1" shackle 31's or 35's depending on my mood
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