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Old 10-17-2019, 12:21 PM   #21
Bob Bidonde
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Default Re: Rewiring . . . What would you do different?

I will be rewiring my Coupe, so here is what I will repeat and what I will do differently:
>Repeat replacing original headlight connectors with three prong modern connectors;
>Repeat adding extra wire support clips on the frame rails;
>Use a main harness with the integral turn signals;
>Add power terminal strip on the inside of the firewall attached with commercial Velcro to run electrical accessories;
>Reroute the dome light power wire to prevent its being pinched at the A Pillar;
>Use jumper wires to assure grounds of 2 OHMS or less from the battery's ground terminal to the car body, the engine & transmission, the ignition points & condenser body, the spark plug bases, the headlight shells, cowl light shells, tail light shells, dome light shell, the instrument light bracket, the steering column housing, and the horn;
>Repeat using 12V with a negative ground;
>Repeat a battery cutoff switch;

>Add a power panel with USB ports and plug ports, so I can use GPS and charge cell phones.
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Old 10-17-2019, 11:12 PM   #22
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Default Re: Rewiring . . . What would you do different?

I would not suggest using any wire less than 14 gauge on a 6 volt system. I rewired my car and used 10 gauge up to the fuse block, 12 gauge for headlights and wiper motor and 14 gauge elsewhere. Remember with a 50 watt headlamp, the current at 6 volts is more than 8 amps. 10 feet of 12 gauge is about 0.02 ohms, so the voltage drop in the wire alone is nearly 0.2 volts. 16 gauge is about 3 times the resistance per foot which means 0.6 volts is lost. Don't forget there are losses in the switch and the connectors. Nearing 1volt loss is quite a chunk out of the 6 volts total.

If you want to flash indicate the stop lights, you must run the brake lights to the direction indicator switch or else the relay.

I color coded the cables but only used modern wire matching as closely as possible the original Ford plan.

I also added a bakelite 4 fuse box replacement normally used for a Volkswagen Beetle because it looked "period". I mounted it on the firewall next to the central junction box for power distribution after the ammeter to four individual fuses for lights, direction signal, horn and wiper motor.

Wiring is fully loomed: no loose strands anywhere.

Last edited by Penthode; 10-17-2019 at 11:26 PM.
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Old 10-18-2019, 10:02 AM   #23
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Default Re: Rewiring . . . What would you do different?

Certainly nothing wrong with heavier wire size, but it has diminishing returns. As Penthode points out, the major loss is in switch contacts and connectors. Which makes a case for converting to 12 volts. Since 12v components use half the current of 6v, the voltage drop across the same network is also half, which produces only 1/2 x 1/2 = 1/4 the power loss.
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Old 10-18-2019, 04:09 PM   #24
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Default Re: Rewiring . . . What would you do different?

I don’t recommend complete rewiring a car unless you have had some schooling in basic electricity, wiring and Ohms law..

Crimping versus soldering needs to be COMPLETELY understood. Both are good and there are
places where each will excel. If crimping is to be even considered, a PROPER tool is required. This is a complete closure type where once started the tool can not be opened unless is is compressed to the maximum before it will release. This is the point where metal migration takes place. A requirement for a proper crimp. Crimping is preferred over soldering for people with limited soldering experience.
A good looking solder joint mechanically is not necessarily a good one electrically.

Wire gauges need to be understood for proper current flow to the various appliances. Too small and the appliance will not operate properly and there will be risk of fire. Too big and the cost will go up and there will be mechanical problems like getting the wires through tight spaces and around corners.
Following the factory wire sizes for a given appliance is a good rule of thumb.

In cases where there is room and you are not restoring original, it is a good plan on vintage cars, to run a separate ground wire to each appliance so you don’t rely on rusty frame joints for a ground. All grounds can be brought back to a common centrally located terminal strip and the main ground made close to or at the battery. The ground wires should be the same size as the hot wires.
A fairly common way to handle the hot wires going out is a terminal strip located at some convenient place with one side all hot and the other side for the individual circuits. If you use circuit breakers they can be mounted directly on the strip.
Each hot wire should have an appropriate fuse of circuit breaker.

Over the years I have wired a couple hundred cars from scratch and I prefer Mil Spec Teflon covered wire for safety reasons. It has a very high flash point and it is usually silver plated for better conductivity and corrosion resistance. It is also cheaper if you get it from the many surplus stores around the country.
I use the small number band tape on each end for circuit ID.
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Old 10-19-2019, 01:54 PM   #25
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Default Re: Rewiring . . . What would you do different?

I start off by using a wiring harness built to factory specs by Sacramento Vintage Ford. I also alter this by wiring straight thru the headlight sockets so that they are terminated in the radiator shell. At the same time I run a dedicated ground that terminates at the battery for the headlights.

For additional circuits I have added, I use 14 gauge color coded wire.

I have a separate terminal fuse block, 6 circuits are switched with the ignition and 6 are on all the time. (see picture)

For all the terminations, I use a crimp tool, utilizing bullet type connectors everywhere except those that terminate at the fuse block.
Attached Images
File Type: jpg Fuse Block.jpg (5.4 KB, 35 views)
File Type: jpg Bullet Connectors & Tool.jpg (46.2 KB, 10 views)
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