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About 6 months ago the 24 volt transformer rectifier on my M915A1’s alternator quit working. Since the only thing 24 volts (other than the military trailer lights) on this truck is the starter, I didn’t worry about it and just put the second set of batteries in the series chain on charge periodically to top them off.
After looking around for a new alternator, I decided to install a Delco 30SI clone with transformer rectifier. The 30SI is a brushless design and has the J180 standard mount that the OE alternator uses. This transformer rectifier unit has a 60 amp automotive rectifier and a 3-phase transformer that uses all stator outputs. The 12-24N transformer rectifier on the OE alternator I took out used a single stator lead with 10 amp maximum output.
The installation is fairly straight forward. Having the truck's air system charged so the fan turns, makes it easier to get the old alternator out and new one back in. The 12-24N transformer on the OE alternator I took out was larger than the alternator body and required a little of finagling to get it out. The new alternator is more streamlined and was easy to get in position. I removed the pulley from the OE alternator and installed it on the new alternator.
When I removed the original alternator, I noticed one of the pivot bolts was loose. Also, I had to remove the pivot bolts to get the belts off. When I installed the new alternator, I found out why. The engine pivot mount interferes with the rear mounting tab on the alternator. I looked at the OE alternator and could see the line where the mounting tab was pressed against the engine mount. Whoever installed the original alternator left the bolt loose so they could get the belts on. I think they either forgot to tighten it, or that would have made the belts too tight.
I didn’t want to fight getting the belts back on so I pulled the alternator back out and ground some relief in the rear mounting tab so it had full rotation. If I was going to do this a lot, I would have used the mill, but the side grinder worked fine and was quick.
When I reinstalled the alternator, the belts went on easy so I think pulling it back out to relive the mounting tab was a good idea. This is a one-wire hookup (two counting the 24 volt wire) so there are no external regulator connections. The wire hook ups are the same as the OE unit I took off.
I started the engine and checked the output voltage. The 12 volt side is 14.0 and the 24 volt side is 28.0, all good, an easy and relatively inexpensive upgrade.
After looking around for a new alternator, I decided to install a Delco 30SI clone with transformer rectifier. The 30SI is a brushless design and has the J180 standard mount that the OE alternator uses. This transformer rectifier unit has a 60 amp automotive rectifier and a 3-phase transformer that uses all stator outputs. The 12-24N transformer rectifier on the OE alternator I took out used a single stator lead with 10 amp maximum output.
The installation is fairly straight forward. Having the truck's air system charged so the fan turns, makes it easier to get the old alternator out and new one back in. The 12-24N transformer on the OE alternator I took out was larger than the alternator body and required a little of finagling to get it out. The new alternator is more streamlined and was easy to get in position. I removed the pulley from the OE alternator and installed it on the new alternator.
When I removed the original alternator, I noticed one of the pivot bolts was loose. Also, I had to remove the pivot bolts to get the belts off. When I installed the new alternator, I found out why. The engine pivot mount interferes with the rear mounting tab on the alternator. I looked at the OE alternator and could see the line where the mounting tab was pressed against the engine mount. Whoever installed the original alternator left the bolt loose so they could get the belts on. I think they either forgot to tighten it, or that would have made the belts too tight.
I didn’t want to fight getting the belts back on so I pulled the alternator back out and ground some relief in the rear mounting tab so it had full rotation. If I was going to do this a lot, I would have used the mill, but the side grinder worked fine and was quick.
When I reinstalled the alternator, the belts went on easy so I think pulling it back out to relive the mounting tab was a good idea. This is a one-wire hookup (two counting the 24 volt wire) so there are no external regulator connections. The wire hook ups are the same as the OE unit I took off.
I started the engine and checked the output voltage. The 12 volt side is 14.0 and the 24 volt side is 28.0, all good, an easy and relatively inexpensive upgrade.
