M925A2 Delco Style Alternator

Tinstar

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Going to a higher amp alternator has made my battery's healthier.
Charges them faster and with less heat.
Another SS member mentioned the same earlier in the thread and it's true.

Truck sat for almost two days and when I turned the battery switch on, the voltmeter was in the green. Engine off.
Not in the yellow as usual.

Man I wish I did this upgrade years ago.
IMG_5693.jpg
Brand New Delco-Remy 33si 100A Alternator
Plus the correct factory Cummins Alternator bracket
 
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74M35A2

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He's so excited, he meant to say alternator bracket. He can now now shut the truck down in any switch order withour an over-volt occurence, which otherwise typically damages the PCB, ABS module, and CTIS controller. This alternator is also not scared to charge low batteries at an idle, an otherwise suicide assignment for stock units.

I have one more of these alternators left, if anybody did not get a good Christmas present, take care of yourself. I have it on sale. Genuine Delco 100 amp brushless 24v 33Si. Not Chinese. It is designed for 1 million miles of usage.
 
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infidel got me

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I've been telling people to throw the govt. alternators in the dumpster since I went to the dark side. I have run this set-up on both my 5 tons and my Humvee with no problems to report. Unless you have to have a military alt. for museum or show purposes, I would ditch the stock wire smoker, electronic eating pos. You save a ton of money-- can be found at local parts store-- and reliable as a buck pocket knife. Thanks to 74m for turning me to the dark side years ago!
 

Tinstar

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He's so excited, he meant to say alternator bracket. He can now now shut the truck down in any switch order withour an over-volt occurence, which otherwise typically damages the PCB, ABS module, and CTIS controller. This alternator is also not scared to charge low batteries at an idle, an otherwise suicide assignment for stock units.

I have one more of these alternators left, if anybody did not get a good Christmas present, take care of yourself. I have it on sale. Genuine Delco 100 amp brushless 24v 33Si. Not Chinese. It is designed for 1 million miles of usage.
Perfect.
When stock alternator smoked (literally) it took out my ABS Module and PCB.
Didn't know about CTIS
Now I know why it's been acting up.
Still works but acting weird.

Now in market for new CTIS controller.
 

vvwilkins

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Team,
Building upon the great information in this thread I just completed the alternator swap in my new-2-me M923A2. Thought I'd provide some details & dimensions required for fabrication to help others via some pics. Hope it helps others. As noted, this is in reference to a M939A2 series truck. I bought the alternator locally from Car-Go in La Habra CA. They also sell on eBay. added a pic of the ad too. Works great. Spacer-LowerBolt.jpg
ThreadChaser.jpgAlt-Brackets-Mount-Dim.jpgAlt-Comp-Notes.jpgCar-Go Alt-ebay-add.jpgAlt-Mnt-2.jpgAlt-Serp2.jpgAlt-Rear-1.jpg
 

tkgvz

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Old thread but I got a new question. Will the pulley from the original alternator work on the delco? I’m thinkig about converting mine. The old one is not charging. It will charge sometimes after a few whacks from a rubber mallet. Thanks.
 

porkysplace

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Old thread but I got a new question. Will the pulley from the original alternator work on the delco? I’m thinkig about converting mine. The old one is not charging. It will charge sometimes after a few whacks from a rubber mallet. Thanks.
PM 74M35A2
If you decide to go to a Delco unless your looking at chinese knockoffs.
 

74M35A2

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They are not the same shaft diameter, plus the stock pulley is junk. Stock shaft diameter is smaller than civilian, stock shaft is keyed which is obsolete and not durable. Most all common civilian heavy truck alternators use a 7/8” shaft diameter, which is 0.875”, including the Delco’s and clones. Modern pulleys spun out of solid bar stock can be had on eBay in double v groove or serpentine 8 groove for about $13 delivered. They are tremendously durable. Some will show a keyway groove in them, you can ignore this and use it regardless. Zap it on tight with an impact and you’re golden. Use a flanged lock nut, or a conventional hex nut with a lock washer. Both methods are mass production common. Make sure your fan clears when rotating, some need a spacer. Stock pulley is not worth machining out, and definently don’t drill it out by hand, it will be all sorts of wonky. A lot of enthusists here want their truck all original, yet have had pulley failures, so your stock pulley may be worth a few dollars if it removes cleanly from the shaft.
 
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jamestiede

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Not only all of what 74M35A2 said is correct..... A smaller diameter pulley is recommended so it will charge at idle. I also changed out the regulator to produce 27.9 volts. Because I don't the truck down the highway for hours it needed to charge more for shorter runs. alternatorparts.com.
 
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74M35A2

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Not only all of what 74M35A2 said is correct..... A smaller diameter pulley is recommended so it will charge at idle. I also changed out the regulator to produce 27.9 volts. Because I don't the truck down the highway for hours it needed to charge more for shorter runs. alternatorparts.com.
Which part is incorrect? Also your alternator should have been adjustable, and not required a regulator change to vary the target voltage set-point. This would be a good case of "Read the TM", I would support.

CARMAN: I am really not selling alternators anymore unless somebody wants something high end such as brushless or high output, as the price on the Delco clones has fallen through the floor and is about $84 right now for a brand new one with new pulley, delivered to your door, with one year warranty.
 
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CARMAN

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Which part is incorrect? Also your alternator should have been adjustable, and not required a regulator change to vary the target voltage set-point. This would be a good case of "Read the TM", I would support.

CARMAN: I am really not selling alternators anymore unless somebody wants something high end such as brushless or high output, as the price on the Delco clones has fallen through the floor and is about $84 right now for a brand new one with new pulley, delivered to your door, with one year warranty.
Got it. Just trying to keep it local!
 
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