hmmwv mod

Hello everyone.
I have a 1987 M998 with the 6.2 in it and 60 amp alternator. V-belts
I replaced the batteries with optima group 34 red tops.

I have a Niehoff 100 amp dual voltage alternator that am wanting to install. NSN:2920014070532


I realize that this topic may have been covered in the past, but with the flood of new hmmwv owners this seems like a logical mod that many of those owners may want to make happen.


I have a few questions:

1. What will need to be changed for me to use this alternator in my truck? are the mounts the same? would the old V-belt pulley from the 60 amp alternator work on this one?

2. I would like to put some sort of a radio in the truck with small speakers. My initial thoughts were to use a radio shelf and build something to hold a radio and a couple of speakers.
What would I need to make this happen with the dual voltage alternator? Would I need another 12V battery?

3. What kinds of radios? and speakers does anyone recommend?

Thank you,
Corey

I prefer the marine style radios with a waterproof remote head. Depending on the alternator the 12v feed can go on the first battery positive. The LMTV's are setup this way. You would have to look at the mounting and see how it is. I have 200a alt brackets that may work if your original one does not. Pioneer makes enclosed speakers its a 5 1/2 and 2 tweeters they work well in the mil trucks you can strap them to the crossbars or put them over back wheelwells.

You will need a steel 100 amp bracket, and a different pulley, and some hardware.
I have the pulley and bracket available.

I would assume that the bracket and pulley would also work on a 6.5 down the road if I swap the motor out, providing it has the V-belt setup?

04mustang said:

I would assume that the bracket and pulley would also work on a 6.5 down the road if I swap the motor out, providing it has the V-belt setup?

Click to expand...

Yes...the V belt 6.5 has same mounting points.

Heres a random thought....

What would be wrong with just running the 12v side of the niehoff directly to a radio setup for power? that way I wouldn't be connected to the 24v circuit at all and when the truck is off the radio is off and cant be used.

04mustang said:

Heres a random thought....

What would be wrong with just running the 12v side of the niehoff directly to a radio setup for power? that way I wouldn't be connected to the 24v circuit at all and when the truck is off the radio is off and cant be used.

Click to expand...

you can run the 12v tap off the alternator to the rear battery, then tap off that battery for your constant 12volts, this way you will alway have 12v power to a power strip on the radio tray. This is how all hmmwv's are wired from the factory running the 4L80E, the TCM is 12volts and terminates on the rear battery, but it would suck that battery down first, even though it is being charged with 24volts, the draw isn't equal, so the 14v tap is for all intents...a rear battery charger.
also remember, the MWO calls for the 14v tap to be grounded to the screw on the alternator and the 14v is not used...I still don't know why this is called for...but only is done on trucks that don't have 4L80E trans.
the 100,200 and 400 amp are replacements for the no longer used 60amp. The 60amp more then sufficient for the basic truck...is was upgraded due to the heavier loads placed on the electrical due to all the gadgets that got installed like blue force tracker, radios, gps etc...