Hello, I have been attempting to rewire a 1939 1.5 ton truck that was just recently given to me by my father. I have been using a kit I bought from Chevs of the 40's, it is for the original generator. The instructions are sort of vague and I am not sure where I am supposed to connect the big wire from the Ammeter to the generator, this was a fire truck for part of its life and it has what looks like a condenser for a radio on the generator. when I attached the wire to this, the ammeter read discharge even with the key off. There is what also looks like a voltage regulator on the firewall that the instructions do not mention. I have very little experience with wiring and the lack of color coordination or markings on gauges is really hampering my progress. Any help or tips are greatly appreciated.
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1952 Chevrolet 3100, Three on the Tree, 4:11 torque tube Updated to: ‘59 235 w/hydraulic lifters, 12v w/alternator, HEI, PCV and Power front Disc Brakes Project Journals Stovebolt Gallery Forum
I have more questions than answers; 1. Is that a condenser on the generator or a cut out relay? 2. Is your new wiring harness designed for a later voltage regulator (with three contacts for voltage regulator, cut out relay and current regulator, like that shown in the wiring diagram linked above)? Or is it designed for just a cut out relay like you would have for a 1937 truck? 3. Is that a headlight relay in your second picture on the firewall (and not a voltage regulator)? This time period was one of transition from having just a cut out relay (1937) to voltage regulator with cut out (1938) to addition of a current regulator (1941, I think). So, no telling what you truck might have in terms of modifications at this point. You need to figure out what you have on your truck, and what your new harness is designed for. Kent
Normally, one wire on the field terminal and one wire on the armature. With an add-on noise suppression capacitor, add wire to armature terminal. The capacitor body is ground and is grounded through the clamp and body of the generator.
From the picture it looks like one terminal is grounded. Doesn't look right to me.
One way to check if the unknown device is a cut-out or capacitor, remove wires and measure resistance (ohms) with meter. A cut-out will measure 0 resistance. If using a digital meter nearly 0 resistance. A capacitor will measure low resistance (may need an analog voltmeter) as it begins charging (meter deflection or change) and measure high resistance when charged (if the capacitor is not dead).
"Adding CFM to a truck will only help at engine speeds you don't want to use." "I found there was nothing to gain beyond 400 CFM."
Libby, by maintaining all those old electrical parts, you are in for your 19th nervous breakdown. As you can see, it's already getting way too complicated trying to figure out and use parts that are probably burnt out, or will be burnt out, and then not available. Their performance and reliability is lousy. You are going to get really confused, especially if wiring is not your thing.
I don't know your goal as far as originality. I hope it does not include wiring. I can help you and save you a whole lot of trouble if you are willing to go 12V. It's simple and gets rid of all those goofy components and wires. Old wiring techniques/electrical systems are nothing to hang onto. Bad idea.
Also: What is the part number of the harness you bought? What motor is in it now?
I see you are putting in a 1958 235 in your 1946. That is a 12V era motor with a 12V starter. So you must already know about 12V conversion?????????
The 1939 wiring diagram on the Hardy site shows two "components" on/near the generator. Labeled "Field resistance" and "circuit breaker". Also shown in 37 but not 40. Some diagrams show a "Polarity Reversing Switch". All a bunch of clap trap.
Well I stepped in and went right over my head on this topic. Did a little reading on 1937-8-9 Delco generators. 1 post, 2 post and 3 post generators. Come back? Early generators used a cut-out (poster's second picture). Add to this GM rebuilt generators had another part number. My head is starting to hurt. 1939 was a design transition year. 1941 all production goes for WW2. Someone with historical knowledge and experience is needed.
I'm satisfied with the 6 volt system in my 55 1st truck. I can still get the correct parts I need. If you are not going 100% original and want to stay with 6 volts, I would definitely update the generator and regulator to the newer 50's design.
"Adding CFM to a truck will only help at engine speeds you don't want to use." "I found there was nothing to gain beyond 400 CFM."
Libby007 Unless your a purist a 1-wire alternator is a good way to go splice bat. and arm. wires at the regulator change bulbs if not done already,gas gauge resistor,heater motor resistors (takes2 )use your fused heater switch. Only trouble may be alternator kinda hard to prime because of low R.P.M. Use as small an alternator pulley as is practical, ammeter should show charge work good. Bartimos is right get it so you can drive it not work on it all the time !!! oop change coils !!
Thanks for all the replies, I will respond to what I can right now. The motor is the original 216 on a 6V system. I am going to take that condenser off, it seems like it doesn't belong. All of the gauges worked prior to this but the cloth sheathing was badly degraded I am trying to work with what I have for right now to keep cost down, will probably upgrade to 12v in the future but thats aways off. Here is the item number for my harness from chevs 1865315P 37^39. Looks like the harness is for a cutout but could I put in a voltage regulater off a '46? I figure I would need to add a couple wires. It mentions a field resistance coil on the generator, not sure where that is. Also this harness has no fuses, i will have to splice in some, what size fuse for the ammeter and does it go on the post on the charging side of the gauge or the opposite? I have it on the posi side right now
I appreciate all the help, I don't have very much experience with wiring and this has been the best place to get answers from those who have done it before.
quick update, that box on the firewall is not a voltage regulator, it is indeed the generator cut out, looks like it was moved there because of the condenser.
If your '39 is like my '37 my comments may help. If not, I will probably confuse you even more.
The harness that you have probably requires you to move the generator cut out to the generator where it belongs. The cut out is essentially a diode that prevents current running from the battery to the generator, turning it into an electric motor when the ignition is on but the motor is off or idling. The field resistance will be located on the body of the light switch. This resistance is bypassed when the light switch is pulled to the first stop (used when there is heavy current demand for heater/radio). The next stop of the switch is for parking lights which also bypasses the resistor, as well as the third and final stop for the headlights. If you don't have such a light switch then none of this is true, such as a later generic switch with the normal off/park/headlight stops.
The ammeter should have a fuse on the body of the gauge. This is your only fuse unless you have placed in line fuses for heater, etc.
By modern standards, or even standards of the late 40s, this system seems archaic. You actually have to look at your ammeter when driving and pull the light switch to the first stop if you are doing stop and go driving or using the radio or heater. On the first stop, no lights come on, you are just bypassing the resistor. Also, if you drive for hours at highway speeds, to keep from overcharging the battery you may want to drive with your lights on. I find this rather charming and part of the character of these older vehicles. Kent
Last edited by Lightholder's Dad; 07/15/202112:26 AM. Reason: clarity
The #1 rule in rebuilding/restoring anything complicated is take a lot of good pictures and have it available for reference.
At the top of your instruction sheet it sheet says 1934-38 Chevy or 1936-38 GMC. Things changed in 1939.
The first step "Wire# 1" on your sheet. There is no cut-out on the generator (your picture) because (I think and don't know 100%) your generator is a newer model. If you know for sure that this generator was working properly then I would get the model number off of the oval Delco plate. Search for information on this model and see how it is supposed to be connected. Post what you have learned on this topic. As I was saying previously, a lot of things changed in 1939 and your truck may have had a change to another generator.
Wire #14 on your sheet. Also look at the note below for Wire #14. What headlight switch type do you have? Attached is a diagram of a 1934 Chevy car.
Last edited by buoymaker; 07/15/202112:47 AM.
"Adding CFM to a truck will only help at engine speeds you don't want to use." "I found there was nothing to gain beyond 400 CFM."
Update: I have my ammeter reading right and the instrument lights working now, just not the headlights. I've had to order the terminal blocks for the headlights that go on the splash aprons, I'm thinking its a ground issue, I had to use the sealed beam conversion plugs supplied with the harness, would have been nice if they labled the wires on those! When the parts come in I'll try them, if everything works I'll post more pictures. Just a quick question, I am using the original cut out on the truck, do they typically get warm while in operation? Mine gets pretty warm to the touch after probably 5 or 10 minutes.
It's hard to help you when we don't know which/what generator you have. Attached is some information on a third brush generator.
Sorry I didn't realize I hadn't mentioned the model, its a Delco Remy 1100002 according to the data plate. Also the headlight switch is one of those universal ones that look like the ones from the '47 and on trucks, it seems to work fine. The instrument lights come on just fine, pretty sure the terminal blocks I ordered will help the headlight problem. I appreciate all the help, it can be a pain at times, but bringing these old trucks back to life is a good feeling.
If someone has a Delco Remy Service Manual page for a 1937 Oldsmobile they could share? If, not maybe the attachment will be good enough.
This is what I read: Delco Remy 1100002 is similar to the 936-T. The 1100002 has higher output current ratings. Fixed third brush. External voltage regulated. Oldsmobile used the Delco Remy 5814 (4 terminal) voltage regulator to go with this generator. Generator terminal "A" to regulator terminal "Gen". Generator terminal "F" to regulator terminal "F". Regulator terminal "Ign." to ignition switch. Note: Olds. switch with at least 3 terminals. Regulator terminal "Bat." to ammeter "+"
In the older Chevrolet Master Parts List, the 1100002 is listed as getting a return credit towards a rebuilt generator.
"Adding CFM to a truck will only help at engine speeds you don't want to use." "I found there was nothing to gain beyond 400 CFM."
If you possibly can, find someone in your area who understands how a 3-brush DC generator works, and pay him twice what he asks to sort out that mess. You'll come out money ahead, as the likely result of the direction you're headed right now is going to end up with a major wiring fire. Asking for advice from most of the people on the stovebolt site is only going to confuse you, as they're far too young to have ever worked with that type of charging system.
If you're going to stay with the 6 volt system and a generator/regulator charging system, at least upgrade to the system with a 2-brush generator and a 3-unit regulator that was used in the early 1950's. In a couple of weeks, I'm headed to east Tennessee to set up that type of system that's been installed as an upgrade to a 1935 Cadillac that's been restored to look brand new. The owner was trying to use the original wiring diagram, which was for a 3-brush generator and a cutout relay.
I have a Delco-Remy service manual from the early 1950's which covers several types of 3-brush charging systems, with wiring diagrams and service procedures. Send me a PM with your email address, and I can send you some copies of the manual pages.
Good luck! Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt! There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway Love your enemies and drive 'em nuts!
If you possibly can, find someone in your area who understands how a 3-brush DC generator works, and pay him twice what he asks to sort out that mess. You'll come out money ahead, as the likely result of the direction you're headed right now is going to end up with a major wiring fire. Asking for advice from most of the people on the stovebolt site is only going to confuse you, as they're far too young to have ever worked with that type of charging system.
If you're going to stay with the 6 volt system and a generator/regulator charging system, at least upgrade to the system with a 2-brush generator and a 3-unit regulator that was used in the early 1950's. In a couple of weeks, I'm headed to east Tennessee to set up that type of system that's been installed as an upgrade to a 1935 Cadillac that's been restored to look brand new. The owner was trying to use the original wiring diagram, which was for a 3-brush generator and a cutout relay.
I have a Delco-Remy service manual from the early 1950's which covers several types of 3-brush charging systems, with wiring diagrams and service procedures. Send me a PM with your email address, and I can send you some copies of the manual pages.
Good luck! Jerry
Sent you a PM, The truck is only going to be used in a short parade in September then will be set aside until I can either get a different generator with a voltage regulator instead of a cut out, or I will convert to 12 Volt.
"Adjustable" third brush generator uses a cut-out. "Fixed" third brush generator uses a matched voltage regulator.
Here it is from vccachat:
The 1938-39 passenger car generator is different from the truck generator. ****The truck used the old 1937 car generator that did not use a voltage control.**** Later there was a Delco Universal generator sold that covered all applications from 1929-39. Its use required different third brush settings and grounding of fields and should not be confused with any of the many generators used from 1929-39. The proper 1938-39 car generator is a 1100004.The universal was a 1100460, later changed to 1100502 in new and 1100503 in rebuilt. These universals are basically a 1939 unit that can be adapted to all applications but not the same as the original 1100004 unit. Among other things it's third brush must be adjusted differently for the various applications and a pully with a fan must be used for the higher settings.
So, the options are:
* To be original, then what's in the truck now is wrong. Need correct generator, cut-out, light switch, etc. * To keep the 1100002, then a Delco Remy 5814 (or equivalent?) is needed. If the generator brushes are worn etc., needs a rebuild. * Update to more modern 6 volt generator and regulator. * Update to more modern 12 volt generator and regulator and do a complete 6 volt to 12 volt conversion. * Update to modern alternator and do a complete 6 volt to 12 volt conversion.
I'm done.
"Adding CFM to a truck will only help at engine speeds you don't want to use." "I found there was nothing to gain beyond 400 CFM."
I'm sending the OP copies of several Delco-Remy service manual pages. Also, there are numerous listings on Ebay for 6 volt cutout relays, at very reasonable prices. Other than normal engine compartment heat, a cutout relay should not get "warm". That probably indicates yours has some dirty points that are causing resistance in the charging circuit and developing some unwanted heat. I'd suggest either wiring the system according to the Delco diagrams with a new cutout, or simply acquiring a 6 volt golf cart battery and running on battery power alone for the one-time parade, using the generator with no wires attached as an idler for the water pump. A golf cart battery will have enough reserve capacity to run the engine for several hours with no charging system, unless a bunch of lights, sirens, etc. are also being operated at the same time. Jerry
Edit: Also on Ebay, there are several 10-SI Delco alternators that have been converted to 6 Volt operation. They're in the $200.00 range, but that makes conversion to alternator charging more or less a "plug and play" situation with very little modification to the rest of the electrical system. No converting of lights, ignition, etc. to 12 volts. Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt! There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway Love your enemies and drive 'em nuts!
