CUCV alternators - I'm still confused

I've been reading CUCV Alternator threads for the past two days.

I've found after reading all of this, I am somewhat confused.

First is this from Wiki CUCV:

Dual 100 amp alternators wired in series to make the 24V. Very strong charging system that will handle any load you can toss at it. Changing over to 12V is NOT recommended.

The Passenger side Alternator MUST HAVE a isolated Ground. The Driver side does not. A Autozone Part number for the DRIVER side alternator is DL7157 (also found in a 1975 cady with a V8 engine) This Alternator is 78 AMP and works just fine. You MUST have a Isolated Ground Alternator for the passenger side. ODIRON is the Best place we have found for the replacment alternator.

http://www.steelsoldiers.com/showwiki.php?title=wiki:cucv&highlight=CUCV+Alternator

One question on this post is are the ALTERNATORS wired in series to make 24v? Or is it how the batteries are wired together? I'm a little fuzzy on this one. I have the TM 9-2320-289-34 wiring diagram (rather large and laminated). The generators do appear they are wired in series via the engine wiring harness block, but I could be reading this wrong.


Then there is this on a whats 24v? thread:

The CUCV alternators are 10 times the alternator you will buy at autozone. They are 100amp, but they are the large chassis alternator. They have more robust windings, and such in them. There is a reason they are so expensive.

As far as repairs on your current setup... Any starter/alternator shop will get you back up and running in no time. Truthfully, you will have more problems buying the cheap autozone stuff, than you will sticking with good high quality rebuilds. You are spending a bunch of $ out of worry. If you are that worried, take that $$ and have your current stuff rebuilt at a good shop... You will not have any trouble with it for quite some time.

http://www.steelsoldiers.com/showthread.php?t=28410&highlight=CUCV+Alternator

The thing is, I went out and bought the drivers side alternator from Autozone part number DL7157 after reading the Wiki CUCV - but it sits on my bench new in it's box untouched. I can always attempt to return it.

Now, having said that, I actually believe the second thread. I DO believe the first thread as well. But I have always subscribed to rebuilding 'old things' (or having it done by a company that pretty much is ALL they do - like rebuilding automotive electrical items) over buying some one elses (Autozone for instance) rebuilt item - which was rebuilt god knows where and by whom.

I was planning on having both alternators that are in my truck right now rebuilt properly and then put up on my shelf so I have a good pair of rebuilt military alternators in case this happens again. I am also planning on ordering the passenger side alternator from Mike at OD Iron.

This brings up my final question. In yet a third thread, it has been said that IF THE ALTERNATORS ARE ORIGINAL (that's one I will have to look at to check for myself), they can be swapped side to side.

From the 'Charging System Help' thread:

As long as you have two ORIGINAL MILITARY alt's they are interchangable. GEN2 MUST (READ ABSOLUTELY MUST!!!!) have an isolated ground.

http://www.steelsoldiers.com/showthread.php?t=27413&highlight=CUCV+Alternator&page=2

SO, the question is, IF the two alternators ARE the originals (must be able to verify that for myself), CAN I JUST BUY TWO ALTERNATORS FROM MIKE AT OD IRON to replace the current ones?

I own a 1985 M1009 - that has been converted to 12 volt by it's previous owner, but I'm in the process of putting it back the correct way. Fortunately, I have a 24 volt 1986 M1031 that I can use as a reference - aka 'polish blueprint'.

It APPEARS that the starter has been changed to 12 volt - heavy red cable goes directly to positive side of the firewall connector. It APPEARS that the battery cables have been changed - both positive battery cables go to positive firewall connection and both negative battery cables go to the negative firewall connection.

The NATO slave plug has had the cables cut and removed from the firewall connector.

Past that, other than the fact that one or two wires have been run off of each battery and appear to have been used to power items that are no longer attached to the vehicle (radios and lights come to mind) the only problems I'm having are dash lights not working properly and my Gen 2 light has NEVER worked - though both my U6TL's are and have always held a charge. Plus my volt meter has never worked properly - I've always thought it's because of the electrical system having been changed over to 12 volt.

All of this research started because my drivers side alternator threw a belt. When I replaced it with a used 'backup' belt, it threw the belt a second time. The third belt was new and it happened again. At this point, I need to mention that I suspect the bearings are starting to go out on the drivers side alternator given the alternator squeals upon startup, but the squealing disappears before the engine warms up.

So, I decided to replace both alternators. Hence the research. Hence the confusion after researching this. The deeper I look, the more differences I find.

SO, can I or can I not buy two alternators from Mike at OD Iron and they will BOTH work properly regardless of which side of the truck they are installed on? The cost difference is about $60 above the costs of the Autozone one, so that's not an issue.

I am so confused. Perhaps I've been looking at the trees and need to step back and look at the forest...

Wallew... here is what I would do...

If you want a spare alternator... Buy 1 from Mike at ODI. Have your current 2 rebuilt, and take the Auto-junk one back. Yes, and autozone one will fit in a pinch... but you will probably have to replace it in a year (just went through this on the wifes Suburban).

If you have one good spare CUCV alternator on the shelf and 2 good ones in the truck, you should be good to go!

mike is right.... I have installed (I found the right part number) the Autozone alternator and it works ok. The military units have a lower RPM excite then the autozone part. the autozone alt may flash the charging light from time to time, and is 22 amps lower out put then the one from
WWW.ODiron.com

Mike,
Thx.

I'll return the Autozone one.

Then purchase two from OD Iron Mike. I'm funny about having a full set of extra's. I even have a full set of fan belts, yet instead of using them, I go buy new ones to replace the new ones I have as backup. Until I get those new ones to replace my backups, I don't use them.

Having one on the shelf is OK. Having 2 properly rebuilt ones on the shelf is where I live...

I even have two spares and rotate SIX tires on my M1009. Go figure.

So, I guess I will order two and they will both work on either side.

thx.

I'm resurrecting this old thread 'cause I need some extra infos.

One of my alts is dead beyond repair, the guy at the repair shop said the rotors windings are gone, broken somewhere inside.

The other alt is still working but shows signs of age, has been rebuilt abt 2 years ago and from then I have to rev engine a little bit at starting to turn off the gen light.

This said, I think the best insurance is buying a set of two new alts.
Reading here, I have been on Odiron website and they have 2 alts listed, #321744 (100A) and #321744-150A.
It would be nice to upgrade to the 150A one, but from the website description it's not clear if the 150A has insulated ground or not (maybe not and can be used only for gen1 ??)
Anybody knows if the 150A version has insulated ground and can be used for both alts?
I want to keep both alts identical for emergency swapping purpose (been there, done that...)

yes the 150 can be used on both sides.

so who has pics, and specs on their alternators?

I sell them, and have offered to help before, i have a line on new, not reman units, and there are a ton of diffrent models available, we just need to be sure which unit we are looking for

If we had the military part number form the alternator that could be switched and used on either side i could get a bunch of them for you guys easily

321744 or the OE #:[FONT=Futura Lt BT, Arial, Helvetica, sans-serif]1105500[/FONT]

good info in this thread.....I had both original alternators rebuilt recently in my 1008...are they side specific when wiring in series?

black06 said:

good info in this thread.....I had both original alternators rebuilt recently in my 1008...are they side specific when wiring in series?

Click to expand...

They are identical, the left side puts out about 14 volts and charges the front battery and it also sends 14 volts to the isolated ground lug on the right alternator which then adds another 14 volts and it outputs about 28 volts to the rear battery - I may be wrong but I think that 28 volts charges both batterys since they are in series??

ok thanks....I had marked them with a grease pen but they came back spray painted and I just wanted to make sure.

Thanks for 'reviving' this thread.

I FINALLY have returned my M1009 to it's 24v configuration. All sorts of things started working properly again. Like the Gen 2 light NOW comes on (then goes off after it starts). Like my 24 volt gauge is NOW working and I KNOW I'm charging both batteries properly, as it sits firmly in the green


If you are driving any CUCV and it's been converted to 12 volts, seriously consider putting it BACK to 24 volts. It's not cheap by any means, but my truck just seems to RUN better than it did as a 12 volt truck.

It even starts way easier than when it was 12 volts. And it is nice to have the 24 volt gauge working.

Thanks again to Mike at ODIron for the two new alternators. And yes, I even swapped them from side to side, to see if it would cause any problems. They work fine, regardless of which side they reside on.

Also, I was talking with Mike and he said the cap that was on the Gen 2 side was not necessary at all. So I got another cap to replace the one that had a broken wire. But when I swapped them from side to side, I did as Mike suggested and just did not install it at all. Everything works exactly as it should.

THANK YOU MIKE...

Now, all I gotta do is come up with the $$$ to pay for a tranny rebuild on an M1028a3 dually that is currently sitting in PA. Ah the vagaries of MV ownership.

Well, I can get new units, cheap, found them, i will know after I talk to my guy on tuesday, I just need to be sure they are correct, new, not reman

Here is my dual Alt on my 1986 M1028A2 5.9L Cummins TH475 Lomax NP205
& yes 24V starter top alt 160Amp SI22 Delco around 200.00 at freightliner.
Bottom is still ICL 100amp delco cucv std.
Hers Photo's 9 day converson & was sick with the crud from Kuwait.
When all Fails Grab a bigger hammer.

Here is Dual alt on M1028A2 cummins

I scraped across this thread and had to give it a good reviving kick. A lot of useful info here.

That's why we always say to search. There is a ton of information already addressed.

Thanks for reviving it again.

Great Info. Thanks for brining it back up. I have an original military alt that failed a test at Autozone. I'm going to take it somewhere local (hopefully) to get it rebuilt. What is a fair price to pay to get it rebuilt? I have no idea whats wrong with it.

bigjmcconnell said:

Great Info. Thanks for brining it back up. I have an original military alt that failed a test at Autozone. I'm going to take it somewhere local (hopefully) to get it rebuilt. What is a fair price to pay to get it rebuilt? I have no idea whats wrong with it.

Click to expand...

A fair price for an alternator rebuild is around $85. I have seen them from $50 to $165. Depends on the shop and what they are replacing.

You can buy the kit and rebuild it yourself for less than $50. This includes all the internal electricals and bearings. The TM 9-2320-289-34 Tech Manual covers the rebuild step buy step with pictures.

http://www.aspwholesale.com/index.php?act=viewProd&productId=5137

http://www.steelsoldiers.com/cucv/54292-cucv-alternator-symptoms-diagnosis-fix.html

Warthog said:

A fair price for an alternator rebuild is around $85. I have seen them from $50 to $165. Depends on the shop and what they are replacing.

You can buy the kit and rebuild it yourself for less than $50. This includes all the internal electricals and bearings. The TM 9-2320-289-34 Tech Manual covers the rebuild step buy step with pictures.

Click to expand...

Thanks. I really don't need an alt but since I have an extra maybe it would be a good idea to have a working spare instead of a NON-working spare