Voltadrop


IHC in the early to mid-fifties.

Rusty Driver
Rusty Driver

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Location: Salem, Orygun

Post Thu Feb 01, 2018 1:05 am

Voltadrop

Got busy with the wiring the other day. Found the usual problems: frayed cloth wiring, cracked insulation, black electrical tape over bare wire, bad crimping. Just about everything including wires just hanging. The voltage regulator (generator) labeled positive ground only, but the truck, 56 S, is 12 volt negative ground. Proably the start of the PO"s electrical problems. I was stumped by the Columbia Vol-ta-drop bolted to the firewall. It had no wires coming to it, or leading from it to a device that would indicate what it was used for. My best guess is IHC wanted to continue to use low voltage guages even after converting their trucks to 12 volt. I suppose it may have something to do with a radio, but there's no radio in the truck. I checked the MT-97 wiring diagrams and none show a voltage reducer. I don't have the S manuals.

I was wondering if anybody had seen one of these gizmos on their truck and know where the wires go.

000_0003_2.JPG
8 volt Columbia vol-ta-drop

Golden Jubilee
Golden Jubilee

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Post Thu Feb 01, 2018 8:01 am

Re: Voltadrop

Voltage regulators "back in the day" had the point material optimized for one polarity or the other, but will function on either, they will just last longer on the one they were designed for. Most replacements today are for either, as they just don't sell enough for two regulators for each application based on polarity.
'56 was right around when the voltage STD was changed. I doubt the resistor was a factory install, IHC was using 12 volt for the export market back in the 40's and may be earlier. Either someone had a 6 volt item they wanted to use, or the truck was built 6 volt and someone changed it and needed to feed 6 volt to something.

Golden Jubilee
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Post Thu Feb 01, 2018 11:04 am

Re: Voltadrop

I think we've determined that the IHC V-8 models during these years were the first to get 12V, while the same year 6 cylinders were 6V until...1957? 1958? Then everything was 12V.
The only reason Volt A Drop was put on the truck was that it got converted from 6v to 12v.
Some people have had really good experiences with Volt A Drop. They were sold everywhere you bought car parts for the longest time.
IHC and its King Seeley electricals may not be a good candidate, though.
My take on 12v conversion:
If wiring is scary you have to replace all of it. Or hope you don't go up in smoke.
Use a integral regulator alternator. Saves about three miles of wire and any number of external connections.
Replace bulbs, of course.
Starter will live.
Heater blower motor can be replaced with a 12v replacement. Or update entire HVAC system. Or use a voltage drop for the blower motor.
Windshield wiper motor--just put the 12v one in.
A great time to wire in a high quality, low pressure electric fuel pump near the fuel tank(s).
Internet sells high-quality electronic voltage reducers for gauges.
Just my humble friggin' opinion.

Rusty Driver
Rusty Driver

Posts: 160

Joined: Sun Mar 30, 2014 5:19 pm

Location: Salem, Orygun

Post Sat Feb 03, 2018 12:41 pm

Re: Voltadrop

Found a couple of dash light bulbs that might give some clues. The GE 57 bulb is a 14 volt bulb. The GE 51 bulb is a 7.5 volt bulb, looks like it is fed by a device bolted to the back of the instrument cluster that easily could be a voltage reducer just for the dash lights.
Still stumped by that positive ground voltage regulator, and that big firewall resistor. I had thought IHC went to 12 volt, negative ground with the '56 trucks, but might not be the case. I'm thinking of hooking up a 6 volt flashlight battery and see if that moves the guages. Just hoping to not fry the guages ( if they're not fried already)

Golden Jubilee
Golden Jubilee

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Location: Lyman, IA

Post Sat Feb 03, 2018 1:55 pm

Re: Voltadrop

I don't understand your "stumped" by a + ground voltage regulator? On a truck with no "electronics" of any kind, I.E. no radio, permanent magnet motor or alternator, polarity doesn't matter, everything will function normally on either polarity. Someone like went from 6 volt + ground and went with 12 volt + ground. If it was done early in the game, there was no set std for polarity and they saw no reason to change polarity, it would require changing the ammeter wires around. It was simple to leave the polarity as it was. Don't over think it. 12 volt + ground was still being used in many heavy trucks well into the 70's.
Someone comes along years later and puts the battery in - ground, (may be even you) and there you are, + ground regulator and - ground truck.
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Golden Jubilee
Golden Jubilee

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Location: Wichita, Kansas

Post Sat Feb 03, 2018 8:11 pm

Re: Voltadrop

IH used the 6 volt gauge set on some 12 volt trucks with a factory voltage reducer just for the gauges. Maybe you have one of those?
viewtopic.php?f=8&t=3135&p=21590

Dean
Lifelong Kansan
Grew up with red paint
Moved off the farm 33 years ago.

Rusty Driver
Rusty Driver

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Joined: Sun Mar 30, 2014 5:19 pm

Location: Salem, Orygun

Post Sun Feb 04, 2018 12:50 pm

Re: Voltadrop

dean466 wrote:IH used the 6 volt gauge set on some 12 volt trucks with a factory voltage reducer just for the gauges. Maybe you have one of those?
viewtopic.php?f=8&t=3135&p=21590

Dean


This is the best explanation for why that voltage reducer is there. Hoping I can confirm the guages are 6 Or 12 before rewiring. There's enough wrong with the wiring to not trust any of it. E-pay has plenty of voltage reducers, not too expensive and probably worth the money to protect the guages.

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