Wiring

[Willie dog]

I know this topic has been discussed before but I can't seem to find any of the posts.

What is involved in converting a b model to negative ground? I know I have to reverse the leads on the heater fan and probably the ammeter gauge and fuel gauge.  Any other things to watch for or change?(besides the battery leads and changing the polarity of the generator)

What might be the pros and cons of doing this?

I am considering using a 8 circuit universal harness from EZ wiring or one of the other companies. 

Thanks for any input from you guys.

[HeavyGunner]

 maybe this will help

[h67st]

If you're going to do all that, you should convert to an alternator.

[Willie dog]

5 minutes ago, h67st said:

If you're going to do all that, you should convert to an alternator.

I was hoping to keep it looking original while modernizing it a bit.

[fxfymn]

I'll play the devil's advocate..What do you gain by going to a negative ground? If you want to use a modern electronic device like a cell charger or GPS it's much easier to make a negative ground auxiliary power box. I made mine out of wood to keep it isolated. You can also run most electronics "backwards" by hooking the power side to the chassis and placing the ground to the truck's "power" side as long as you isolate the device from the truck's chassis.

Converting means changing gauges, possibly the starter motor, as well as moving other wires around. I just don't see the great gain for the work involved.

[j hancock]

Some good and bad doing the pos. to neg. swap.

Here is a link to alternators that look like generators that maybe helpful to keep the original appearance.

http://www.jegs.com/p/Powermaster/Powermaster-PowerGEN-Alternators/757123/10002/-1

[Willie dog]

Great info and thoughts. 

My main thought for the conversion is to be able to use an aftermarket, universal wiring harness. I want to make sure I can use such a thing  to replace the original.  I have looked at reproduction factory wiring harnesses but I am having a hard time swallowing the  $1200 to $1600 price tag for them. Call me cheap but I gotta save where I can. 

I'm not much of an electrical engineer, I know just enough to be dangerous. 

[eddeere]

I think you covered everything. Heater motor, fuel gauge, & amp meter . Most starters will turn the correct direction neg. or pos . ground. Just re polarize your generator.   

[41chevy]

No need to replace amp meter, you just swap the wires from side to side, other wise it will read discharge when it is charging. The wiring does not care if it is pos or neg ground the load through it is the same. You are only changing the path to ground not the volts or amperes. Even somebody with a vintage car going from 6 to 12 volt the wiring is not an issue.

  FYI if you leave the pos ground there are Delco positive ground Alternators and  if you want to run LED's there are now Positive Ground LED bulbs for vehicles. Made mainly for the British resto vehicles and available through Foreign auto parts.

Edited November 28, 2017 by 41chevy

[Willie dog]

Thanks everyone for the info and advice.  I'm sure I'm making it harder in my mind than it actually is.  I've re-wired a few projects with the universal harnesses and had no problems. The positive ground issue kinda threw me off a bit.

Still not sure if I should change the ground or not. Any other thoughts?

[HarryS]

When I did the conversion to eliminate the 12/24 series parallel switch I had to change the temp gauge and fuel gauge along with the sending unit. I got the gauges and matching sending unit from Summit Racing. They were SW which fit the holes and looks of the originals. I think I saw somewhere on here that SW made the gauges for Mack. Good Luck.

[Maddog13407]

being a B42 with a401 all you really need is a small Chevy 1 wire alternator also. I converted my B61 over and I don't remember if I ever did anything with the heater and defroster motors. I also used the stock harness as a pattern,replaced all the old wiring with with new wire of the same guage and the old glass fuse panel in the glovebox with a modern one out of a new B model with circuit breakers

[HarryS]

Now that you mention it I didn't change anything with the heater motor. It works fine (so far).

[41chevy]

7 hours ago, Willie dog said:

Thanks everyone for the info and advice.  I'm sure I'm making it harder in my mind than it actually is.  I've re-wired a few projects with the universal harnesses and had no problems. The positive ground issue kinda threw me off a bit.

Still not sure if I should change the ground or not. Any other thoughts?

If it all worked before,and you had no issues, why change it?

[fxfymn]

Wiring a vintage truck is pretty simple to do one wire at a time if you choose to do so. You basically have two options; remove the existing harness and make a new one to match it or pull each wire individually using a container to run the wires through such as asphaltic wire loom.

I solder every connection and use heat shrink to make the connections look like the originals. It is kind of tedious work, but after you master the soldering process it is pretty straight forward. I make up a rack from plywood and conduit to hang the rolls of wire on so you can pull multiple wires at once to make up a loom.

Have you checked with Brillman?  https://brillman.com/ A friend uses him to make harnesses for his restorations by copying the existing harness. I use him for supplies. He had a fire that cost him his wiring loom machines, but I think he has replaced them.

RI wiring has a stock harness http://www.riwire.com/ A bit pricey at $1129.00, but you will always be able to look at the finished product and think to yourself that you did it right instead of wishing that you had. The cost will fade over time, but the less than perfect job will be there every time you get into the truck to remind you that you cut a corner. Just my $.02.

Another thing to consider is using marine power outlets (cigarette lighters). They are plastic and can be wired to power a modern accessory no matter the ground without running a wire all the way back to the battery. https://www.amazon.com/gp/product/B00RJVJJCI/ref=oh_aui_search_detailpage?ie=UTF8&psc=1

[Willie dog]

Thanks everyone for the great info. It's always good to get different opinions and experiences from different sources. That's why I like this group so much. No one judges anyone or bashes anyone's posts.

 Unlike some of the antique cars for sale groups I belong to on Facebook. UGH!  Don't even get me started on that.

[Hobert62]

My opinion is I didn't trust 55 year old wiring with brittle insulation and decades of hack jobs.   I cut every wire out of the truck and started new.  I started with  a 14 circuit universal street rod kit from ebay.  I have 3 circuits not currently used, i plan on one for a radio and 1 for elec wipers.   I put  2 of the marine power plugs in fxfymn mentioned.  They came in a panel on ebay, but I threw that away. Their plastic with a big plastic nut on the back to secure(just drilled a hole). 1 is a USB plug other is cigaret style.   I think have 5 circuits I ran through relays also.  High & low beam, trailer lights, and 2 for tractor lights.    I like the alternator idea also, but I know where your coming from on the look.  On our 2 johndeere's  I still have the generators because they are right out in the open and an alternator looks way out of place. The farmall is hid under the hood so that got changed.  

[Willie dog]

2 hours ago, Hobert62 said:

My opinion is I didn't trust 55 year old wiring with brittle insulation and decades of hack jobs.   I cut every wire out of the truck and started new.  I started with  a 14 circuit universal street rod kit from ebay.  I have 3 circuits not currently used, i plan on one for a radio and 1 for elec wipers.   I put  2 of the marine power plugs in fxfymn mentioned.  They came in a panel on ebay, but I threw that away. Their plastic with a big plastic nut on the back to secure(just drilled a hole). 1 is a USB plug other is cigaret style.   I think have 5 circuits I ran through relays also.  High & low beam, trailer lights, and 2 for tractor lights.    I like the alternator idea also, but I know where your coming from on the look.  On our 2 johndeere's  I still have the generators because they are right out in the open and an alternator looks way out of place. The farmall is hid under the hood so that got changed.  

Beautiful.  That is exactly what I plan to do. New wiring harness, looks original while modernizing it.  I may even incorporate the old original fuse panel to appear stock original......make it so it will flip down and have the new fuse panel behind it. Open the glove box and you can see the old panel, behind it is the new one.

[Freightrain]

You can have the generator repolarized and run it with neg ground.  That way you keep the originality you like.

http://fergusontractors.org/nfs/wp-content/uploads/technical-articles/Polarizing-a-Generator.pdf

[steelman]

The voltage will not change.  It will remain the voltage it was wound to.  Polarizing changes the ground and positive connections, not voltage. 

[41chevy]

21 hours ago, Willie dog said:

Beautiful.  That is exactly what I plan to do. New wiring harness, looks original while modernizing it.  I may even incorporate the old original fuse panel to appear stock original......make it so it will flip down and have the new fuse panel behind it. Open the glove box and you can see the old panel, behind it is the new one.

I used these people to have a "secret" alternator on our 1941 Chevy,has the Stock OEM look, but is a Alternator internally. One wire hook up too, the others were for show only. 

 

https://www.gener-nator.com/details.htm

Edited November 30, 2017 by 41chevy

[Freightrain]

1 hour ago, steelman said:

The voltage will not change.  It will remain the voltage it was wound to.  Polarizing changes the ground and positive connections, not voltage. 

I realize he is not changing voltage(I just used that link to show it can be done), but you can make your positive ground generator into a negative ground and continue to use it on the truck.

[fxfymn]

Quote

My opinion is I didn't trust 55 year old wiring with brittle insulation and decades of hack jobs

When I first bought the 52 I removed a five gallon bucket full of wiring and everything still worked. Apparently the answer to any electrical problem for the Richmond City shops was to run a new circuit and just leave the old wiring in place. Talk about a rats nest.

Took the old girl to a local Christmas parade yesterday and the turn signals didn't work. I'll get to that sometime this winter as I won't take her out again until next spring.

I had something occur in my travel trailer that is applicable to truck wiring as well. The battery was not charging, so I replaced the old transformer based charger with a new electronic version and all seemed well. The next time I used it the battery was dead again so I assumed I had a loose or broken wire between the battery and the charger. I had 12 volts at the battery and 13.6 at the charger, so I started measuring the voltage along the wiring and much to my surprise I had high voltage on one side of a circuit breaker and low on the other. The circuit breaker still allowed current flow, but apparently the contacts had become pitted over the years which made it a resistor. I replaced the breaker and now the battery is receiving the voltage it should. Something to keep in mind if lights are dim or other low voltage gremlins appear.

Edited December 3, 2017 by fxfymn