Who's done a total 24v to 12v conversion?

[SeriesShorty]

Anyone? Just looking for some real world advice as opposed to a few vague threads from over the pond that I've found, and not just "my cousins uncles friend of a friend" or "I heard..." stuff, but actual personal experience with doing this.

Thanks!

[Les Parker]

We have done the engine electrics (dist/coil/plugs wires etc.) but not recently had the need to go the whole way and do the wipers/alternator/starter headlamps etc.

[greenmeanie]

I did it on my 101. THey were built as 12v or 24V so it was a matter of sourcing the 12V parts and swapping them in. Fortunately on these trucks most of the 24V harness is exactly the same as the 12V other than wiring the alternator.

Lets see. New parts were Delco 10SI alternator plus mounting bracket I made, bulbs all round including the instrument panel, wiper motor, starter motor (I think but it has been swapped since so I can't remember), heater motor, horn, flasher/indicator control box, fuses, voltage reducer for the instruments and, of course, the big monster dizzy, plug leads and plugs got swapped for 12V items. Finally I replaced the leads from the now single 12V battery to the starter.

Typically you'll be pulling twice the current for each component so it pays to give your harness the once over but it should be up to the job as is.

If your truck has the military 6 way light switch plus the infrared relay switch and you want halogens then you want to eliminate the infrared relay as it will quickly burn out and then add the commonly discussed relays for your headlights.

Oh, and while your doing all things electrical its a good time to go through the harness cleaning and dielectric greasing all connnections and grounds.

That was about it. It's not really difficult but sourcing all the 12V parts can get expensive.

[SeriesShorty]

Thanks Greenmeanie, that was very helpful.

I've already done the partial conversion for the ignition components using a voltage dropper but as you've probably read I've been having some issues with things not working quite right.

Then last weekend the starter solenoid (and maybe the starter) took a dump so at this point it may be cheaper to just go ahead and finish a 100% conversion. And I'm blowing fuses to the ignition bits at the 12v fuseblock I installed coming directly off the voltage dropper, so that is frustrating. I've also got a burnt up wiring harness going to the right headlight from a bare spot hitting the body. So I've got some serious issues going on already...

Here is a list of what I've already done:

Distributor
Spark Plugs
Plug Wires
Coil

Starters and Alternators are fairly cheap to source. But it's all the other little things that add up. And I fully admit that I am not great with electrical stuff. I'm wondering if my skills are up to completing a conversion because lord knows I'm having difficulty with the half and half set up I've got now. It seems as though a fully 12v or fully 24v is going to be more reliable than my "hybrid". ???

[scatterling]

I've been agonising over the conversion for my rebuild as well. Here is a link to what apparently needs to be changed.
http://www.series123.com/repairs_electrics24v.html

[SeriesShorty]

I saw that list too, it's great. I wonder if Ikes alternator bracket works for these types of conversions, too?

It's driving me crazy making this decision and in the meantime my truck just sits begging me to make up my damn mind! rofl

[scatterling]

Ike's bracket should be fine. I think you've already made your mind up. Just think of all the shiny new parts! :D

[SeriesShorty]

And I do like shiny things...I'm like a cat that way.

Hmmm, and a friend of mine has an old 88" scrapped in his garage. Let me see if I can sweet talk him out of a few gauges and a horn.

So I'd need the pulley off of a 12 volt water pump to swap over to my military water pump. Sounds pretty straight forward there...yank off military pulley and press on civvy pulley. And I've seen a blown 2.25 in friends garage as well.

Then I'll check out Teriann's page again on adding the relays to the headlamps and new wire while I'm at it due to what I affectionately call the "august harness incident leaving me stranded and surrounded by drunks in North St. Louis"...(think early scene in National Lampoons Vacation).

I just had my old 24v solenoid tested and it tested good. So that means my starter is probably the culprit. So Neil, I think you're right...I think my mind IS made up. :)

Now for some sweet talking and offers of chocolate, beer and babysitting in exchange for my friends 12v goodies. :p

[SeriesShorty]

Checking around for alternators right now.

See they are available in 2 groove or 6 groove pulleys...which is needed?

Also see they come in 1 wire hook up, and 3 wire hook up...any tips on which to get?

Thanks again!
Jen

[scatterling]

you only really need the one groove pulley. Found this site
http://www.alternatorparts.com/alternators_gm.htm
Considering the 10 SI and 12 SI are the same dimensionally I would use the 12 and get a 1 wire setup.
When I changed my generator to a 24 volt alternator I bought a 1 wire setup - it's just simpler to install, self exciting and internally regulated.
Ran a wire from the alternator to the solenoid and done! :thumb-up:

[SeriesShorty]

Thanks Niel, great link too!

What bracket did you use to mount it...did you fab your own?

I wonder which side of the engine do most 24v to 12v conversion folks mount the new alternator. Since we don't have a battery in the engine compartment we have all that space on the passenger side (for LHD vehicles). I'm wondering if I could put the 12v alternator in the same place as the generator is now. Seems like a good idea with the exhaust area putting off so much heat.

[scatterling]

I bought a bracket kit from Robert Davis and my alternator is mounted in the stock Series position on the lower section below the intake manifold.
It would be easy to mount it where the generator is now - maybe with some modification Ike's kit will work. Also, if you browse the alternator site, they have various brackets (cheap!) which might work with a little tweaking.

[greenmeanie]

For the 10 vs 12SI debate I would simply figure out roughly what your electrical demands are and go for the cheapest unit that meets them. A 63A 10SI should meet the demands of most series trucks. Avoid going for any of the high output 10SI as they generaly push the unit too hard temperature wise, especially if you mount it anywhere near the manifolds. A dual groove pully is a good idea for anything approaching 100A.

As for 1 wire vs 3 wire hook up here is a good webiste that explains the advantages of a 3 wire among other good electric upgrades.
Linky (http://madelectrical.com/electrical-tech.shtml)

[SeriesShorty]

Thanks GM!

I had time to take a peek at my truck again the other day and I'm trying to figure out why the series123 conversion parts list claims you need to swap the water pump pulley/fan. Seems like I'd be able to use my stock military set up for those. :confused:

[jac04]

Thanks GM!

I had time to take a peek at my truck again the other day and I'm trying to figure out why the series123 conversion parts list claims you need to swap the water pump pulley/fan. Seems like I'd be able to use my stock military set up for those. :confused:

The center diameter of the military double pulley is larger than its civilian counterpart. This diameter is used to center the pulley on the water pump flange, so it needs to be correct. I found this out when trying to install my military double pulley on a civilian water pump.

[Mudtub]

I made a simple u bracket and mounted it on the right side of the motor where there are four holes foe the old gen. I went to napa and found a belt. It was very easy with no batt in the way.

[kevkon]

I have a question regarding the alternator (Lucas 43 amp) wiring on a SIII. Why do some schematics show one brown wire from the alterator to solonoid while others show two? Was it a matter of using 2 lighter gauge wires?

[jac04]

^^ I was just looking at that myself, funny. My wiring diagram only shows one brown wire, but I have two.
The two brown wires connect to different terminals on the alternator. The larger brown wire should be for the alternator output to the positive side of the solenoid. The small brown wire should be for the alternator "sense" terminal to the positive side of the solenoid. The brown & yellow wire goes to the ignition warning light.

[kevkon]

I know, my SIII has only one from the alt to solonoid. Just wondering if that's correct or a PO changed it.

[kevkon]

So should there be two or one ?

[Les Parker]

Factory wiring for the Lucas Alternator has 3 wires connected to the back of the alternator.

[Nium]

Factory wiring for the Lucas Alternator has 3 wires connected to the back of the alternator.

So one wire is for the Charge warning light, one is for the charging the battery, so what's the third (attached to S post on alternator, I think) for exciting alternator? If it is an exciting wire can't the charge wire just be jumped to the S post from the "+" post on the alternator and do away with the third wire?

[SeriesShorty]

Heck, and mine is even more different since it was a radio truck. I've got a whole bundle of wires going into my stock 90amp generator! It's making my head hurt thinking about it. I leave for vacation tomorrow in the Disco so poor Series is gonna have to wait his turn.

[jac04]

So one wire is for the Charge warning light, one is for the charging the battery, so what's the third (attached to S post on alternator, I think) for exciting alternator? If it is an exciting wire can't the charge wire just be jumped to the S post from the "+" post on the alternator and do away with the third wire?
You could do that, but the 'sense' wire is best connected directly to the positive side of the battery.

[kevkon]

I'm curious, why run two wires to the + batt ( solenoid)? Mine has one 10 ga. What gauge are the 2 wires?

[greenmeanie]

You could do that, but the 'sense' wire is best connected directly to the positive side of the battery.

The sense wire is best connected to the main load point of the harness and not the battery. Read the previously posted link for the detail.

I won't guarrantee this is the naswer but if your truck has been converted to a higher amp alternator then adding a second wire to the existing harness to make up current carrying capacity is a common trick rather than replacing them entirely with a single heavier gauge piece.

[jac04]

The sense wire is best connected to the main load point of the harness and not the battery. Read the previously posted link for the detail.
Yup, sorry for the error. My sense wire is hooked up at the + connection at the solenoid.

[SeriesShorty]

Here are some pics of what I am working with since the FFR trucks seem to be quite a bit different.

http://s233.photobucket.com/albums/ee284/sailorjennie6/Pics%20for%20Conversion/

Attached is the stock wiring diagram that shows all the wiring to the generator and generator/shunt panel. Scratching my head with what to do to hook up an alternator since I've got all these extra wires.

I'm back from vacation and figured I'd pick back up on this before it gets too cold to do much.

[scatterling]

I removed all of the wiring for the gen. and shunt panel. My alternator is the single wire kind - so all I had to run was a wire from the alt. to the solenoid.