Restoring the '48 Special Deluxe

[morrias]

Hello all,

 

My father just retired last year and has finally started working on his 1948 Plymouth Special Deluxe sedan.  He bought the car in Oregon back in the early 70's when he was in college.  It's been sitting in their garage pretty much since then.  I actually learned how to drive stick on it before getting my first car.  I've been going over to his place the last few weekend as it needs some love to get things up and running again.  It looks like most of the wiring in the engine bay is shot, the insulation is crumlbing and the copper looks pretty bad.

 

Does anyone have any good schematics of the wiring, and what are the gauges of wire used?  It looks like most things are 8 - 14 gauge from what I can tell.  We're probably just going to start with modern wire, but maybe we should consider getting some of the older cloth covered wire if it is easy to find.

 

Should be a fun project, I look forward to seeing the old gal up and running again.  It's in pretty good shape with the original interior, I'll have to get some pics up.  I love electrical work, so I'm going to enjoy making it function again.

 

Thanks!

[MarcDeSoto]

If you are planning to stick to the 6 volt battery, which I recommend, be sure you use the same gauge wire as original.  If you don't want to pay for a new wiring harness as I did, there are some articles out there on how to make your own harness using the same cloth covered wire.  Of course that would cost more than going with modern plastic covered wire.  There is an article on this subject in the Nov.-Dec. 2014 issue of Old Cars "Guide to Auto Restoration". 

[BobT-47P15]

Here's a P15 wiring diagram, but it does not give wire gauges.  I think gauges are listed on the 49 and up diagrams.

 

You guys need to get a Repair Manual and Parts Manual for the car.......can usually be found on eBay.

Those answer many (but not all) questions.

 

Have fun and enjoy your project to get it shaped up again.

 

[Young Ed]

Here's a P15 wiring diagram, but it does not give wire gauges.  I think gauges are listed on the 49 and up diagrams.

 

You guys need to get a Repair Manual and Parts Manual for the car.......can usually be found on eBay.

Those answer many (but not all) questions.

 

Have fun and enjoy your project to get it shaped up again.

 

 

Yup the 46-54 shop manual has all the wiring diagrams and for some reason only the p15 one doesn't have the gauges listed. I used my old intact but worn harness this diagram and the p18 one for sizes to rewire my car. I also upgraded anything that was 16 to 14 to try and help the lights be a little brighter and to save on wire sizes to buy.

[morrias]

Thank you very much, I'll have to grab one of those manuals.

 

I ended up buying a bunch of 14 gauge, so it looks like that should work for most of the wires under the hood.  The wierd thing is that the newer 14gauge looks thinner than the original 16 gauge.

 

Hoping I can get enough of the wiring done to attempt a start today!

[DonaldSmith]

The new wire insulations are so much better than the old ones.  I understand that the wire was braided with a fabric covering to strengthen the insulation of the time, plus adding color-coding to the wire.   So the new insulated wire is much thinner overall for the same wire gauge.  

 

I re-wired my car with the new wire, and then bought some fabric-covered for the engine compartment, for show.  Installation of the fabric-colored wire is an ongoing project, and is somewhere on my to-do list.

 

There are several threads on this forum about rewiring.  Good luck finding them.      

[soth122003]

I did my rewire under the hood and the parking/brake lights to the back. While the P-15 wiring diagram did not have the wire sizes, others have posted a generic Chrystler wiring schematic that had the wire sizes and I went by that, mostly. 10 gage for headlights, generator, voltage regulator and 12-14 gage for running lights, instruments and peripherals. A lot of it was matching the old wire sizes. Basically the larger the current load the larger the wire.

 

Joe

[morrias]

Thanks, got the coil and generator all wired up today.  It is kinda trying to start, but having some issues.  Time for a carb rebuild!

[greg g]

You may also consider repowering the brake light switch. Currently it is powered through the main fuse mounted on the headlamp switch. It can sometimes cause failed fuse issues, and that fuse controls all the lights on the car. It is a simple matter to run a dedicated line through an online fuse (20 amp should do) to replace the stock power lead. Power the new line from the battery side large post of the starter solenoid directly to the in terminal on the switch. You can abandon the old line in place after taping it off. This change will make the brake lamp brighter and keep the headlamps from dimming when the brakes are on.

As far as wire size is concerned remember that current flow and good grounds are the two things the 6V systems like to keep everything up to snuff. Consider also adding a ground strap from the body to the frame or engine.

Edited February 2, 2015 by greg g

[MarcDeSoto]

Sounds like a "sound" idea Greg.  I think I'll try that on my 48 DeSoto too. 

[soth122003]

Dedicated the brake wire as well. Used an inline 15amp fuse and it's still working great.

[_shel_ny]

Some wiring diagrams in the "resources" section.

 

Should be downloadable.

 

http://p15-d24.com/files/category/1-reference-information/

 

 

You may also want to consider modifications to make all 3 red lights in the rear function as brake lights.

Original set up is the center high light is the only brake light.

Some socket changes (to dual contact) may be necessary if you do not currently have signal lights.

This can be searched here. It has been covered a few times.

Edited February 3, 2015 by shel_ny

[jeffsunzeri]

A word of caution:

 

Be very careful in selecting the wire for your re-wire job. You may know about this if you are electrically savvy, but just in case it's worth repeating.

 

You need to select wiring not just on gauge size, but number of strands as well.

The type of wire and insulation is also very important.

All 14 gauges are not equal in all respects. The AWG size refers only to the equivalent of a solid wire.

For stranded wire, a second number indicates the number of strands, such as 14/7 which would indicate 14 gauge made up of 7 strands.

Count the number of strands of the wire you will be replacing.

When purchasing new wire, try to use just one supplier and use a comparable strand count as OEM.

 

Cheap wire typically has cheap insulation.

Aircraft grade wire is meant for aircraft installations, not automotive. Although of higher quality insulation and wire, it is not meant for the automotive environment, especially where flexing is required.

Gauge is assumed to be AWG sizing. Much imported wire is not sized to AWG sizes, and is approximated.

 

Before undertaking a re-wire job I like to have all the wiring on hand and from the same supplier so I don't run out of one size or color, and have to source from a second supplier.

Buy the best terminals you can afford and use the best expensive crimping tool available.

 

Just my personal preference, but do not leave the color coded blue/red/yellow plastic visible on the connectors. Cover them with black shrink tubing for a professional job. Nothing shouts "AMATEUR" louder than a bunch of red and blue crimp connectors under the hood.

[Dave72dt]

With a little tug, you can pull those red, yellow and blue collars off, solder or crimp the connections and then heat shrink, no bulky insulators under the shrink tubing.

Edited February 3, 2015 by Dave72dt

[Frank Elder]

People sink thousands into engines, interior work, and paint/bright work........but they wont spend the extra 20 dollars it takes to heat shrink all their connections......that just boggles my mind. Not to mention It just looks like $tuff....

[48ply1stcar]

I did basicly what Young Ed did.  I used modern wire, the color code from the P15 diagram, and the wire guage information from the P-18 diagram.

 

Then I just replaced one wire at a time.  Frank is right, I must have been a hurry that week.