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CUCV alternators - I'm still confused

gmjunky87

gmjunky87

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okay, I bought a DL7157 alternator at auto zone (on the left in picture), I have a dumb question, where is the post for the ground? and do you need it? I have the gen 1 alternator out (on right in picture)
 

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trukhead

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gmjunky87 said:
okay, I bought a DL7157 alternator at auto zone (on the left in picture), I have a dumb question, where is the post for the ground? and do you need it? I have the gen 1 alternator out (on right in picture)
Click to expand...
One on left does not look like an isolated ground alternator.
The black looking bolt towards the center looks to be a ground attachment but it is screwed directly into the case making this alternator a chassis ground alternator.

I do believe one alternator on the drivers side on the CUCV grounds directly to the block via a wire from the Isolated ground terminal. You must observe and check this to confirm for your self. If this is confirmed you should be able to use a chassis ground alternator in that location only. The passenger alternator has the ground going into the series portion of the charging circuit to create the 0 to 12 volt side of the 24 volt system. (The isolated ground wire connects to the positive of the battery that is chassis grounded).
Look at the wiring diagram in the TM untill you understand what you are seeing and can find the wires under the hood.
I am telling you this from memory and it is your responsibility to confirm this for you self before connecting wires.
 
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Warthog

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The reason you do not have a ground post on the DL7157 unit is because it is NOT an isolated ground alternator. It uses the housing as the ground. that is why you CAN NOT use the unit on the passenger side.

No need for the ground wire. Just don't throw it away as you may need it in the future if you reinstall the isolated ground unit.
 
gmjunky87

gmjunky87

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ok I'll just tape up the ground wires and zip tie they out of the way. after reading some other post's that's what I figured but just wanted to make sure. Thanks!
 
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Hollywood1980

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Guys I know this is an old one but my drivers side alt has just gone do you have any new recommendations of where to buy a new one? Ps I'm in the UK so will need to get it shipped over here as well.

Russ
 
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Rvitko

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They are pretty easy to rebuild, my advice is to rebuild what you have. Aspwholesale has a kit to do it. What I don't like about a new one is that they are not real ac delco but a clone and I believe the frame is inferior and the windings seem less durable. Outside of a good standard driver set, access to a press to press the bearings out and in and a bit of emery cloth for the contacts, you will also need to make a support for the frame so it isn't damaged from pressing the bearings, I used a very heavy walled cardboard tube but pvc pipe works as well. If you want to go new, there are many listings on eBay. For the driver side, isolated ground is not necessary, but if you want it to be right, after assembly be sure no terminals have continuity with the frame and during assembly be sure all the insulating washers are in place. A tip here from my screw up, pull the wire that holds the brushes in before testing, I didn't and was pulling my hair out trying to figure out why I had continuity between the brush terminals and the frame. Technically for the driver side you can use a Cadillac 27si alternator, non isolated ground. I personally prefer both are isolated ground so in a pinch, I could buy the non isolated and swap my driver side to passenger since you won't likely find isolated ground units readily available.
 
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shiner13

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rockspider said:
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...)
Click to expand...

Thanks for all the great info on SS. The thoughtful responses on this site are much of the reason i have been able to own and enjoy these trucks. First time for me to post on here. After wading through all of the different threads on alternators, I'm hoping to get some updated help on my current situation. I just got home with an M1028 i purchased through an auction on eBay. It is in extremely good shape overall and very low miles, but has already been having electrical issues. My first M1008 had been converted to a 12V system previously, so this is my first time figuring out the 24V system.

My head is spinning a bit from the info overload after reading all the posts today, so was hoping for some concise help to these questions:

1) Do both of the alternators need to be rated as 24V units?
- When I try looking up the part numbers given in all the threads, they take me to 12V alternators, and most of the model numbers given are discontinued and not available. Everything under the hood looks new/clean. I tried to get model/# info off my existing alts. Gen2 i could not find any stamped info on the case anywhere. Gen1 has DelcoRemy 1105500 12V stamped in it. I looked at rebuild kits, but I'm not even sure the newish looking alternators I have a the correct ones for a 24V truck.

2) Does anyone know of good, currently available alternators that would work? I'd rather avoid the autozone type versions.
- I would love to find something 150A, as I have some additional lighting/winch etc in future plans. From what I could tell, The AC Delco 27SIs were replaced by the 28SI models. I did find some 24V/100 amp versions of this one, but they were $410+... I'm hoping to convert my 1008 back to 24V also, so I might be looking for 4x good alternators. That would definitely be out of budget.

I'm sure I will be asking for more help as I actually try to diagnose the full problem, but I will wait and post more details after I have had the chance to run through the TM diagnostics and previously posted answers.

Thank you!
 
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shiner13

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As an update, I found some alternators online, but it was the part number listed in the TMs for the M1010 (4629JA) not the number listed for the rest of the CUCVs (1105500). Prestolite Military High Output Alternators - NSN:2920-01-131-4932 - 28V 100A

Will these work? I doubt it now that I realize I haven't seen any posts about it. I mistakenly thought that the 4629JA was the part # for the Gen2 and that 1105500 was the part# for the Gen1. Thought they were different since all of the posts about the aftermarket ones made a distinction between the two. Finally realized I was reading the TM wrong.
 
richingalveston

richingalveston

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no that is a 24v alt. you need a 12. The way the cucv system works it it produces 12v in the first alt and then puts that into the second where it comes out at 24. Alternators are the same as batteries. you put them in series and they double the voltage.

however to put two alternators in series, the second has to have an isolated ground. which means it actually has no ground so thus it can take 12volts and turn it into 24.

you need a 12v isolated ground on the passenger side and a 12 alt on drivers side which does not have to be isolated ground but can be. If it is then you have to add a wire to ground it.

;
 
MarcusOReallyus

MarcusOReallyus

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Yep. Think of them like two flashlight batteries stacked in your flashlight. If you connect the negative of BOTH of them to the flashlight body (ground), you'd have a dead short.
 
cucvrus

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I will assume that you are wanting alternator parts? Excuse me for my ignorance of your terms. I do not know what a rotor is in an alternator.
[COLOR=rgba(0, 0, 0, 0.870588)]Leidy Repair
Website
Directions




[COLOR=#878787 !important]Auto Electrical Service[/COLOR]



[/COLOR]

Address: 2427 S 5th Ave, Lebanon, PA 17042


Phone: (717) 949-2905


Hours: [COLOR=#212121 !important]Open today · 7:30AM–5:30PM
I have had great success using this vendor for all my CUCV and HMMWV electrical parts. Nothing really special about a CUCV alternator except the isolated ground. Good Luck. I hope that helps you out.






[/COLOR]​
 
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addinquir

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You do not know what a rotor is for an alternator?
I am just curious, what brought you to this SS web site and especially this page?
I am just curious.
The rotor is the rotating magnetic field that induces a current in the stator windings.
If you have difficulty with this info, I recommend going to YouTube and searching for HOW AN ALTERNATOR WORKS.
This way, ypu can get up to speed and get more out of these discussions.
 
cucvrus

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No I just never paid attention to the operational parts of an alternator. I just remove them and drop them off and pick them up when they are repaired/rebuilt. I am sure I could rebuild one if I had the desire. But I let well enough alone and give that work to someone else. I was amazed at the tools and equipment that was used at a fully equipped electrical shop. Not something I want to learn. That is where money of mine is well spent. So far I have not had any issues with my rebuilds from Leid. They just keep going. When I think of rotors I go for brake rotors. But you learn something new everyday. I will keep that in mind if I ever need to use that information. But Leidy will have what you want. Have a great day.
 
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