Complete rewiring and the recurring 6V vs 12V debate

[Tim Frank]

Over the winter I am going to have to rewire the beast; I ripped down the headliner and inspected the wiring that runs in a channel above the doors, front to back.

The insulation, when touched, simply disintegrated into a powder leaving bare wires (OK, I know...don't touch any more wires... ). It is a fire hazard and I offer that as a heads-up to anyone who might have original wiring.

I will either buy a pre-made harness or make my own, but I would be interested in some opinions on whether 6V or 12 V is the way to stay/go.

Currently it is the 6V +Gnd. system.

What I am most interested in is whether anyone rewired and did not go to 12V and now regrets it....or anyone who went to 12V and now regrets that.

I know that this has been a frequent topic and apologise up front to anyone who is tired of the issue.

Thanks, Tim

[Young Ed]

Tim

I'm happy with the 6v system on my truck and car. I do plan to go 12v on my p23. Now with that said here's my thoughts on your question: wire for 6vs and you can use the harness for 6 or 12. If you wire it for 12 the wiring wouldn't be able to handle 6v. So I say wire for 6 and decide later.

[Tim Frank]

Thanks for the input.

I intend to buy or make a full copy of the existing 6V. harness with equal or larger gauge wire, but I will have decided whether to end up as a 6 or 12 volt system before I start.

[JohnS48plm]

My 6 volt is just fine. Always starts and with a 12 volt inverter I can have a 12 volt radio/cd player. JohnS48plm

[martybose]

I ran my car as a 6 volt for a number of years, after adding a 6V alternator and changing the headlights to 6V 60 watt halogens (needed headlight relays and heavier wiring for that). I finally switched to 12V after giving up on trying to make the stock gas gauge work, but all of the aftermarket ones were 12V.

I rewired my car using a Rhode Island harness, which I highly recommend. I actually specified a number of changes (adding turn signal wiring, eliminating the voltage regulator becuase of a 1 wire GM alternator, incorporating the headlight relay and wire gauge changes, and more) and everything came out exactly as I wanted it. Not cheap; guess it depends on what you think your time is worth to do it yourself!

Marty

[De Soto Frank]

Use the heavier gauge wire, as if you were planning on staying six-volt... as mentioned before, if you or "the next guy" decides to go 12-volt or back to 6-volt, the wiring will be of ample capacity for either path.

Unless you really need modern convenience features such as CD/ Satellite radio, and other goodies that cannot be found in 6-volt versions, there is no need to ditch the MoPar six-volt system.

When they are properly ( even moderately) maintained, they are entirely reliable and sufficient. Twenty-five years of driving 6-volt iron has taught me this... I still don't carry jumper cables ! ( Okay, maybe that's not something to brag about, and makes me a "bad Boy Scout", but I simply haven't needed them for the six-volt cars...)

And, if you have insulation literally falling off the harness, you should plan on rewiring.

Good luck !

De Soto Frank

[bob westphal]

I may as well add my two cents. I rewired my P-15 coupe with wiring that I made up as per the original wiring diagram and kept the positive ground 6V. It works very well. The trick is new wires of at least the same size as original. The lighting, dash included, is bright and easy to see with at night. Starting is fast.

I have used Rhode Island wiring on several cars. On each I had the main power soarse wire that goes to the starter burn up when I started to use the cars. This wire was too small 14Ga. I replaced the wires and everything works fine. The cost for the wiring material I used on my P-15 was about $30 as opposed to R.I. $280 Plus I still have material left over to use on another project.

Bob

[Normspeed]

I rewired mine and kept it 6v it was inexpensive and easy. Just tag everything before removal, and transfer the tags to each new wire as it's made up. I also installed 00 battery cables. The car starts easy and the lights are bright. I installed a 12 volt step up under the dash to power my XM portable satellite radio and other small 12v stuff. Here's a pic of the new harness going in. Once it was in, I covered the wires with black split loom covering.

[teardrop puller]

I am in the process of re-wiring my P18 right now. I bought mult-circuit fuse pannel from the "Bay". Used relays for the lights, fuel pump, horn, and an extra. I just used the wiring diagram from serrvice manual as a guide. Lots of terminal strips and wires joined at the strips.

So far I have powered up lots of circuits and no smoke yet. Let's hope there will be no smoke.

I am going to be very happy with the wires, the old ones instulation curmbled right off.

kai

[FMSPEED49]

I've been looking at the 12vot step ups, so they are enough to handle a cd player eh?

BTW i rewired and stayed 6v just based on it lasted 57 years, figure it works well enough.

[Guest rockabillybassman]

The stock wiring in my P26 crumbled to the touch too, so I tore the whole lot out and rewired for 12v neg. I added in a flasher circuit, also a fuse box and light and horn relays. For the wipers I got a 10/20 amp dropper, and for the fuel guage an electronics friend built a little dropper, but it's not too accurate, so I might replace it with a Runtz from Night Prowlers. The 6v horns and starter work fine on 12v, but I installed a 12v gen, reg, and coil with a resistor. I used heavy wiring so I could go back to 6v, but I think hell will freeze over before that happens!

[Normspeed]

Here's the one I used. Well made, operates flawlessly. It will handle a 6 amp 12 volt load. Converts 6v pos ground to 12 v neg ground.

http://www.pressenter.com/~cmeyer/

[blueskies]

I decided to rewire for 12v when I did my '50.

While there is nothing wrong with a properly maintained 6v system, my thinking is that if you are replacing the whole system anyway, might as well make it 12v so that you can take advantage of using a fuse block and the ability to run 12v accessories. Unless, of course, you are a purist and are shooting for a factory correct resto.

My generator was original to the car, as were my headlights, misc bulbs, and wiring. All of the wiring was losing it's insulation, so a total rewire was in order. I've had old wires catch fire several times in the past in my '53 chevy truck before it's rewire, and didn't want to go there... Many of the bulbs were burned out, including one of the bull's eye headlights.

I decided since I wanted the car to be completely reliable for long trips, I didn't want to rely on the old generator, so I needed a new or rebuilt one. The cost of a factory correct wiring harness is about double the cost of the EZ-Wiring harness I bought. So, since I had to replace nearly the entire system anyway, there was no reason for me to spend more for a 6v system and be unable to use a cell phone charger or converted radio (without spending even more for a converter). The only electric guage in the car is the fuel guage, and it works just fine with a Runtz 12-6 volt electronic reducer that prevents surges, for $19.

I'm also running a GM HEI, which is only available for 12v - systems. The advantage of a new 12v wiring harness is that you also get a fuse block. Mine has 21 circuits, lots of fuses to prevent meltdowns when something goes wrong... When I did my truck years ago, I did it one wire at a time, and the result was a rats nest of wires that are mostly the same color and are unlabled. The new wiring harnesses have the wires labled every 6" so you know what they are for no matter where you find them in the car.

I'm happy with my 12v conversion, I'd do it again.

Pete

[Normspeed]

Pete, I've seen those E Z harnesses. They sure look well put together. I like the idea of the wires being marked at intervals.

[Tim Frank]

As always in here, great feedback and common sense.

Thanks for all of it!

And if there is anyone in the group with original wiring they have not checked recently....preferably in one or more of the closed in areas, I think there are enough stories in this thread to suggest that it may be time.

[Tim Frank]

Pete,

How are the EZ Harnesses supplied?

Can you specify wire gauges and are the wires all the same length, which you then cut down as required and add the appropriate connectors?

I looked at the complete reproduction units, but with a D25-C they aren't sure that they can do an exact match. I thought of ordering a P-15 harness and doing whatever hopefully minor mods would be required.

I asked in the forum a while ago if anyone knew whether the P-15 harness was the same as the D25-C, but there was mixed response.

At that point Ifound a few sources of components to do your own complete custom harness...many colours and gauges, good range of multi-pin connectors etc.

So I may do that instead.

The EZ harness is worth investigating.

Last question...does anyone know where I could get a copy of the wiring diagram for a 1948 P-15 to use as a guide?

Rgds,

Tim

[Tim Frank]

Thanks for the info. BTW (and very OT)...I thought that the All Blacks looked great against the Poms two weeks ago, although I thought the hosts did get robbed on that first non-try.

Rgds,

Tim

[Guest rockabillybassman]

Hey Tim, (very OT!) you are a man of impeccable taste, with a fine eye for a well-crafted game! Being a kiwi, the All Blacks are obviously my heroes, and I truly believe that this time they're on track to win the World Cup.

[greg g]

So what songs do you fellows sing in the third half????

[Brendan D25]

Tim, I have a shop manual for the D25 and it shows the wiring diagram as being for both the D25 and the P15. I don't have the means to send you a copy online but I could probably could get it photocopied and mail it to you. I must have been away when you were looking for this info before. I was gone pretty well all of Oct. Brendan.

[blueskies]

Pete, I've seen those E Z harnesses. They sure look well put together. I like the idea of the wires being marked at intervals.

Norm- Most of the aftermarket wiring kits like this have the wires labled every few inches. Most of them also have the wires color coded. When I bought my EZ Wiring harness, they didn't offer the colored wire version. A few months later, they came out with the color version for the same price. At first, I wished that I could trade, but now that it's done, I kinda like the all black wires because they sort of dissappear visually.

Pete,

How are the EZ Harnesses supplied?

Can you specify wire gauges and are the wires all the same length, which you then cut down as required and add the appropriate connectors?

Rgds,

Tim

Tim- The EZ harness is a universal type kit, they have several different versions with different numbers of circuits for differnet needs. Mine is a 21 circuit fuse block. I bought this so that I would have room for expansion in the future if I ever decided to to things like an electric fan, or AC, power windows, whatever. The wire guages are based on the loads for various circuits. The main power feed, headlights, etc. are heavier guage wires.

One thing I liked about the EZ kit is that all the wires are already connected to the fuse block. Which to me, means that there is half the chance that I would screw up a connection and have something fail. All I had to do was mount the fuse block, and start pulling the wires where they were supposed to go. The wires are grouped in bundles, for the dash section, rear section, front section, steering column section, etc. to make it a bit easier to figure out. The wires are long enough to reach wherever they are supposed to go, and are cut to fit.

One caveat with the EZ kit, the instruction manual is nearly worthless for some sections, and dismal for the rest. The diagrams are crude hand drawn pictographs, and it's hard to differentiate the diagram for a V8 engine and the diagram for the fuse block... The charging system and turn signal sections were so lousy that I finally downloaded the Painless Wiring manual PDF from the Painless website to figure it out. The EZ kit is designed for the guy chevy 350, chevy tilt column, and chevy one wire alternator. Of course, I didn't have any of these things, and I did a three wire mopar alternator with an external regulator. Once I got my head around it, it wasn't too difficult.

Go to the chassis section of my website, www.50plymouth.com, for more info on my setup.

Pete

[Guest Dave Claussen]

Has anyone used the Painless harness? Are the instructions better quality than the EZ wire system? I have looked at both at great length and have not been able to make a decision one way or the other. I'm not an electrical genius, so I'm looking for the most user friendly system out there. Thanks, Dave

[blueskies]

Has anyone used the Painless harness? Are the instructions better quality than the EZ wire system? I have looked at both at great length and have not been able to make a decision one way or the other. I'm not an electrical genius, so I'm looking for the most user friendly system out there. Thanks, Dave

Dave-

The Painless instructions are available as a free pdf download on their website. You can download them and check them out. Their instructions are a manual that is 20+ pages. The EZ instructions, by contrast, are I think 4 or 5 pages... Clearly the weak part of the EZ product.

I bought the EZ harness because of the price. At the time, it was the least expensive one that I could find. It wasn't really that difficult, even with the lousy instructions. And, as I mentioned above, you can use the free Painless instructions as a suppliment.

Pete