Putting a 24 volt alternator into a M37 with the 100 Amp kit.

I have equipped both an M-37 and an M-43 with single wire alternators.  The M37 had a 100 amp kit.  The M43 was easy.

Most competent auto-electric shops can convert the Delco 10S alternator to 24 volt. I live near Fort Hood, Texas, and one of the better local auto-electric shops is run by a knowledgeable retired Motor Sergeant. He is very supportive of military vehicle restoration efforts. He has built single wire alternators for my son and me in 6, 8, and 24 volt versions. He makes them "self-energizing" to support the single wire feature.  This was several years ago.  Now single wire alternators are available "off the shelf" in both 12v and 24v versions. 


The first thing is to remove everything ahead of the ammeter - generator, voltage regulator, and the heavy cables.  The 100 amp kit includes a big diode that is in front of the radiator, and a four belt pulley.  You only need two fan belts.  More on this later...


The most difficult part of the conversion is fabricating a replacement alternator mount.  You can use the old generator mount by adding a small pipe collar as a spacer over a long bolt to mount and locate the alternator. There are "universal" mounts available that are pricey and look like something from my childhood "Erector" set. 

I did my first conversion to a single wire alternator back in 1996 when I converted my WDX to a 12 volt alternator.  Being my first such enterprise, I used a piece of lightweight wide angle iron to the replace the generator mount on the engine block and then I welded on "L" shaped tabs spaced to match the alternator mount. It's the neatest and sturdiest method.  The drawback was that there was no adjustment for aligning the belt pulleys. 

When I did the M37 and the M43, I left the original generator mounting bracket on the engine block and used a sturdy steel strap which I formed into an inverted "U" that fit the existing generator bracket.  The rear of the "U" can be seen in the photo.  Next I made a shorter "U" bracket on which I mounted the alternator. This upper "U" had slotted bolt holes so the upper "U" could be moved to insure the fan belt pulleys were in alignment.  The upper "U" can also be seen.




The 100 amp kit uses four "V" belts which are needed because of the increased load of the 100 amp generator.  You can leave the four belt pulleys in place on the crankshaft and the water pump.  The "V" belts on the four belt set up are narrower and more like standard "V" belts.  I chose to use two belts since they were each smaller than the single "V" belt used in the standard M37 charging system  This required me to buy a two groove pulley.  Some rebuilt alternators may have a single groove pulley, but generally neither new or "off the shelf" rebuilds come with a pulley.  Now that we have both "V" belts and serpentine belts, the buyer always has to make the a choice of pulleys.  New pulleys are pricey. 

The standard charging system on other "M" series Dodges to include the M43 used one belt which was thicker like the "V" belt on my Ford 9N tractor.  This meant I would have to find a "wide" groove pulley for the alternator.  The diameter of the alternator shaft was the same as that on the 24v generator.  The original 24v generator had a long shaft and the pulley has a "snout" to move the pulley out to be in line with the fan belt.  My friend at the generator shop suggested we use the original "wide" grove pulley from the M43's 24v generator by placing it in a lathe chuck and cutting off the "snout" on the backside of the pulley. The large diameter of the old pulley is not an issue since the higher output of the alternator is equal to or greater than the generator's.


To wire in the single wire alternator, run a minimum 10-gauge wire direct from the alternator to the ammeter and then from the ammeter to the battery post on the foot starter switch.

In this photo, the black 10 gauge wire on the left in the picture is coming from ammeter and goes to the battery post on the starter.  The heavy cable from the battery is at the upper right.  The blue wire powers some accessory circuits.

If you have converted to a solenoid, run the wire from the ammeter to the battery post of the solenoid. 

There are expensive conversion kits available, but this is all that is required.