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Converting From Generator to Alternator

Katavic918

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This morning around 4:30 while out with the dog I smelled the faint but unmistakable smell of electrical burning. I walked by the deuce and caught a strong whiff. I disconnected the batteries and started looking in the cab and under the hood. Yup, you guessed it, stupid Generator. Lucky it didn't burn the truck down. I had a previous incident with the generator on my HMMWV which had done it's best to try and catch fire while I was driving about 2 weeks ago. So after I converted that to an alternator I purchased another one to eventually change the deuce over as well. Eventually came sooner than I expected. I was pretty simple using 1-1/4" x 1/4" bar stock, some grade 8 bolts, and a spacer. Anyway, here are the results.

DSC_1188.jpgDSC_1189.jpgDSC_1193.jpgDSC_1197.jpg
 

Katavic918

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Delco 21-si. Also, you'll need one of these "2 groove diesel truck alternator pulley 3-1/8 dia. 7/8 bore"

Edit: Also I should probably note that the clearance between the fan and shaft nut is only about a quarter of an inch. You can maximize this distance by loosening the stock generator bracket and holding it back while re tightening the bolts.
 
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77 AMG

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Question. Why not mount the alternator BEHIND the adjustment bracket, so that you have more space between the fan and pulley? Space the pulley forward, and the nut/shaft would be farther away from the fan, yes? Is the mounting ear next to the engine block not able to be mount like that? My Gen. is either on the way out or is out, as the amp gauge is reading low.
 

Katavic918

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Correct. The lower ear has to be mounted the way it is therefore the upper ear has to be on that side of the adjustment bracket. I'm not really worried about the clearance because A, the fan doesn't flex and B, even if it did flex it would move away from the nut since it is pulling air not pushing it. In the event that the fan blade did contact the nut (maybe if the water pump bearings started to go bad) it would be with the side of the fan blade that is raked away from the nut. In other words the blade would skip over the nut and not cut into it. There is a company that makes a similar kit to this and they specifically say that the nut for their alternator will be close to the fan. I'm not sure how close they mean but if it's worth noting then my guess is it's pretty close.

Edit: Also, the pulley wouldn't be lined up.
 
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77 AMG

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Ah, okay. My truck isn't home yet, otherwise, I would have gone out and looked at it for a better picture of the how/why. Thanks.
 

vampeel

New member
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Everett, wa
I am curious the switch between generator to alternator affect anything?
And how to wire in this new alternator? Is it positive to positive of battery and ground to frame, and just skip the regulator on the truck?

Sent from my SM-G930U using Tapatalk
 

dmetalmiki

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London England
Nice modification. And of course (refers to the last question) The unit is 'Self Regulating',?.
So quite easy to wire in.
Switch.
Alternator. (Exciter wire).
Battery.
 

frank8003

In Memorial
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My original 1969 M352A generator needed adjustment, all froze up. I fixed all that + took it to generator shop where they hooked up my $800 generator wrong and let out all the smoke.

Went and bought a replacement, went right in, zero problems, Low cost, Happy.
Alternator test and adjust M35A2.jpgIMG_2794.jpgIMG_2800.jpg
 

Katavic918

Active member
523
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Location
Maryland
I am curious the switch between generator to alternator affect anything?
And how to wire in this new alternator? Is it positive to positive of battery and ground to frame, and just skip the regulator on the truck?

Sent from my SM-G930U using Tapatalk
If you use the 21si alternator, then it is just positive to positive and negative to negative. The exiter wire is not used on this particular alternator. It will not affect anything and it is self regulated at 27.4 volts.

Edit: I should also add that if you are using a battery disconnect for your battery negative you must not turn off your batterys while the engine is running. This will damage the alternator.
 
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frank8003

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What kind of alt is that?
It is from Wolverinetech..............
It was not $239 when I bought it but it is now. The kit is complete. It is one wire.
I took and refurbished to almost new all the grounds and connections.
The alternator failed in six months and they sent new diodes for free and I fixed it.
Highly recommended.

Just goto
http://www.wolverinetechnologiesllc.com/AlternatorKitM35M54.html

or if you want to do special stuff try this
http://www.wolverinetechnologiesllc.com/12vaddonkit.html
 

74M35A2

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Livonia, MI
Alternator itself can be had for $69 new (not rebuilt), delivered, with 1 year warranty. They are not really Delco, but instead Chinese Delco clones. Quality seems to be fine though. Wolverine's kit includes all the attachment bolts/nuts/washers/spacers to make it work without 100 trips to the hardware store, but I think his reputation is taking a beating here lately. Not sure.
 
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Subaugusta710

New member
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4
3
Location
Lake Wylie SC
This morning around 4:30 while out with the dog I smelled the faint but unmistakable smell of electrical burning. I walked by the deuce and caught a strong whiff. I disconnected the batteries and started looking in the cab and under the hood. Yup, you guessed it, stupid Generator. Lucky it didn't burn the truck down. I had a previous incident with the generator on my HMMWV which had done it's best to try and catch fire while I was driving about 2 weeks ago. So after I converted that to an alternator I purchased another one to eventually change the deuce over as well. Eventually came sooner than I expected. I was pretty simple using 1-1/4" x 1/4" bar stock, some grade 8 bolts, and a spacer. Anyway, here are the results.

View attachment 744558View attachment 744559View attachment 744560View attachment 744561
Hi- nice work. I’m thinking of converting my M998. Do you have any photos or a write-up for that? Thanks
 

Katavic918

Active member
523
54
28
Location
Maryland
Hi- nice work. I’m thinking of converting my M998. Do you have any photos or a write-up for that? Thanks
Pretty simple. The only issues were getting the belt/pulley to line up and kicking the bottom of the alternator out so it doesn't hit the oem bracket. I've seen other write ups where they cut the bracket to make it fit, but I didn't want to do that. The last picture is from the m35a2 just to show the wiring. Just positive and ground. Any other wires are not used. I want to say that you'll need 62" belts but I would measure after you get everything installed to make sure. Also I must note, with this alternator, I must be connected to the batteries while running or it will fry itself. In other words, if you have a battery disconnect switch, don't turn it off while the engine is running. Good luck.
 

Attachments

dReed39

Member
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Hinesville, GA
Pretty simple. The only issues were getting the belt/pulley to line up and kicking the bottom of the alternator out so it doesn't hit the oem bracket. I've seen other write ups where they cut the bracket to make it fit, but I didn't want to do that. The last picture is from the m35a2 just to show the wiring. Just positive and ground. Any other wires are not used. I want to say that you'll need 62" belts but I would measure after you get everything installed to make sure. Also I must note, with this alternator, I must be connected to the batteries while running or it will fry itself. In other words, if you have a battery disconnect switch, don't turn it off while the engine is running. Good luck.
Awesome works, man! Nice
My uncle got this incoming M998 project we'll work on after we finished installing the brake kit and dually wheels on the current Superduty project. We're going to get a new alt for the M998.
 

Holub9097

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Virginia
My generator seems to be going out or just doesn’t have the juice to keep up with what I’ve added on. I was curious though, does the 200 amp HMMWV alternator fit?
 
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