CUCV Alternator Rebuild

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Tow4

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On the way to the Georgia Rally this year my driver side alternator started over charging. I stopped to check it and at idle the charge was normal but the voltage increased as the rpms did getting to 17+ volts. After checking connections I disconnected the B+ wire off the back of the alternator and continued the trip.

After getting home I pulled the alternator off and took it apart. I ordered replacement parts and did a partial rebuild of the alternator. Since the brushes had very little wear I elected not to replace the bearings.

Rebuilding alternators is easy and usually straight forward. This series of GM alternators are easier than many because all the internal connections use fasteners.

The process is as follows:

Remove the 4 case bolts. The rear end casting should pull off with the stator, use a screw driver to loosen the stator from the front casting if necessary. Remove the 3 nuts that attach the stator leads to the rectifier and with a screw driver loosen the stator from the end casting and set it aside.

As you remove the internal components make note of the insulators on the B+ bolt and relay terminal bolt next to it. The 4 8/32 screws that attach the regulator/brush holder assembly and one side of the rectifier have insulating sleeves on the shoulder, Make sure these aren’t damaged. There is an insulator between the rectifier negative heat sink and end casting on the opposite side from the B- bolt. There is an insulating sleeve on the B- bolt that goes between the rectifier negative heat sink and through the end casting. Check these are there and in good condition.

If you elect to replace the bearings, be sure you support the casting near the bearing as you press them out and in so you don’t break the casting.

Assembly is the easy, just be sure the insulators go back where they should.
IMG_20151105_140632_750 copy.jpg

The B- bolt will be a little snug going into the negative heat sink slot. Just tap it in and be sure the insulator is on the bolt as shown.
IMG_20151105_141617_796 copy.jpg

Install the rectifier and lightly snug the 8/32 screw and nut on the B- bolt. Note the wire going under the 8/32 screw. Check to make sure the B- bolt is square with the negative heat sink. You may have to remove the rectifier and tap the bolt sideways to get it to line up correctly with the through hole in the end casting so you don’t cut the insulator when you tighten it down.
IMG_20151105_142524_212 copy.jpg

Place the foam dust shield over the regulator terminals and place the brush holder on the regulator. The heat sink on the regulator goes against the end casting. The brush retaining pin goes through a hole in the back of the end casting and is removed after the alternator is completely assembled.
IMG_20151105_143452_612.jpg

Place the trio over the rectifier terminals and install the relay terminal bolt with insulators and terminal. Attach the resistor, trio terminal, and wire terminal to the regulator as shown. Be careful installing the 3 regulator/brush holder screws so the insulators are not damaged. Install the B+ bolt with insulators, terminal, and self tapping screw into the positive heat sink. Attach capacitor terminal to the positive heat sink using a self tapping screw.
IMG_20151105_145601_392.jpg

Recheck all of the fasteners and make sure all are tight. Install the stator lining up the 3 stator leads with the rectifier terminals and the slots on the outside of the stator with the end casting then tap into the end casting. Install the 3 nuts on the rectifier terminals and tighten. Check the 3 stator leads are not touching the negative heat sink.

Carefully place the end casting assembly over the front casting and rotor assembly so the rotor goes into the end casting bearing. There is a alignment pin on the end casting that goes into a hole on the front casting. Once everything is together, install the 4 case bolts and snug lightly. Spin the pulley to make sure nothing is binding or rubbing. If all is good, tighten the case bolts and pull the brush retaining pin.

Install the alternator in the vehicle, check operation, and you are done.

I’m offering rebuild kits in the classifieds.

http://www.steelsoldiers.com/showthread.php?146702-Delco-Alternator-Rebuild-kits-for-alternator-p-n-1105500
 
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MarcusOReallyus

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Nice write-up!

ASP Wholesale is a great place to get the kits. Good prices, good service. I went with them because Warthog recommended them, and I'm glad I did.

They have the rebuild kit, and also a parts kit which has a bunch of the miscellaneous parts that aren't included in the kit. These aren't usually needed, but when I rebuilt both of mine, I did get one hardware kit, and wound up using a few of the parts. Glad I bought it.
 

Tow4

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Nice write-up!

ASP Wholesale is a great place to get the kits. Good prices, good service. I went with them because Warthog recommended them, and I'm glad I did.

They have the rebuild kit, and also a parts kit which has a bunch of the miscellaneous parts that aren't included in the kit. These aren't usually needed, but when I rebuilt both of mine, I did get one hardware kit, and wound up using a few of the parts. Glad I bought it.
I get my parts the same place they do and will custom build a kit to include only the parts you need.
 

2deuce

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I had about 8 alternators to rebuild recently and found out 4 of them had bad rotors. They had shorts. I figured that they were toast, but held onto them with the hope there was a fix for this that I was missing, because when the rotor is bad it is too expensive to replace. Otherwise the others usually had bad regulators. The regulators couldn't be tested, I just put a new one in. I have never had a triple diode burn out that I can remember. I only replaced the part that was bad and cleaned the rest.
 

Tow4

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I had about 8 alternators to rebuild recently and found out 4 of them had bad rotors. They had shorts. I figured that they were toast, but held onto them with the hope there was a fix for this that I was missing, because when the rotor is bad it is too expensive to replace. Otherwise the others usually had bad regulators. The regulators couldn't be tested, I just put a new one in. I have never had a triple diode burn out that I can remember. I only replaced the part that was bad and cleaned the rest.
Rotors are not that expensive, send me a PM if you are interested in replacing them.
 

Indyharleyguy

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Hi if there were a HEMP would these internal parts be fried? I was told this is the only electronic part on the M1009 and would be good to have a spare in a Faraday cage?
 

Warthog

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Reread the forum rules. No EMP decisions are allowed

Besides it has no connection to rebuilding an alternator.
 

sawbonz

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hello . im new here and am helping Vets here in my area n GA . im working on a CUCV M1008 PU . the alternator . ( pass side ) is shorted out. wire burned off. question . i see a isolated grounded ALT. on the drivers side . and am told i need a dif alt for the Passenger side.. 27 pi 100 ? where can i get one and is it rebuildable ? thank u


i was not able to server with those who served .
so i server those who have brian w smith
 

Warthog

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On a stock CUCV you have to have an isolated ground alternator on the passenger side. From the factory GM install the same alternator on both sides.

If you need to get it running right now you can move the drivers side to the passenger side and install a regular alternator on the drives side. You can get an alternator for a 75 Cadilac. The part number is in the FAQ thread or the Wiki.

DO NOT use you old alternator as a core. Keep it and rebuild it for less than $50.
 

Tow4

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Once you disassemble the failed alternator you can look at the pictures above and determine if all the insulators, terminals etc. are there and their condition. If you need anything other than what's in the rebuild kit I can supply it.

Here is the link to the classified thread on the rebuild kit.

http://www.steelsoldiers.com/showthread.php?t=146702
 
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Tanaga

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I'm rebuilding a M1028 passenger side alternator and my kit has a different part than the parts kit. Should I use the old part or do you think it's okay to use the replacement part? See picture. New part on bottom.
image.jpg
Also my alternator has a little white box with wires coming out both sides that sits on top of the rectifier and the alternator in the write up doesn't have this. What is it? I should say that my truck came with the 12 volt conversion from DNR so this is the only alternator.

image.jpg
Also my alternator didn't have this thing (see 3rd pic) but the kit and the write up alternator did.
image.jpg
 
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Tow4

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I'm not familiar with the parts you have. The regulator with the wire attached to the threaded post is not the OE for the stock unit. That is usually used in one wire conversions. It's hard to say without knowing the model number.

The resistor in your third picture is not used in all delco alternators, but has been in the CUCV ones I've seen. You can reuse it.
 

Tanaga

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Sorry Tow4, I don't know what all these parts are called. I'm going to guess that my alternator is not stock. It now looks like the one shown in your write up except I left that white thing in the 2nd picture. Hopefully it isn't going to fry anything.

One more question: My alternator had a cover over the 2 flat blades on the regulator so there was just a ground wire and a red wire connected to the back. The 2 blade plug is still on the harness so I can plug it in if I remove the plug. Should I? Is this why my original regulator had a wire attached? Keep in mind that this has been converted to 12volts, don't know if that matters or not.

Thanks
 
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Warthog

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Your alternator has been converted to a single wire self exciting unit. Many hotrodders use them. I have never worked one one. I would take it to a shop so I didn't burn something up.
 

Tanaga

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Well I think I just converted it back, didn't I? There's just that unknown small white box that's left. See upper right in picture. This picture was taken before I did the parts swap.

image.jpg
 
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Tow4

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The square box in the top right can be removed.

Make sure you have all the parts shown and hooked up as shown in my guide in the first post. I don't see a relay terminal in your last picture.

Make sure you have all the insulators and insulated screws. The unit must be isolated ground to use on the passenger side with the stock 24 volt system.
 

Tanaga

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That white square box is a ceramic resistor. Anyone know what it does? Never mind I figured it out. Thanks.
image.jpgimage.jpg
 
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