Wiper Conversion from Vacuum to 12V

[Gene F]

I got caught in the rain again with my 57 Ford a couple of weeks ago. I use Rainex, but there is still nothing like having good wipers when those big fat raindrops are coming down. My vacuum wipers work, but they are still lees than adequate. I can't see spending $110 on another vacuum wiper motor, just to end up with the same thing. The vacuum assist on the fuel pump, to me does very little. So I ordered the kit to convert the system over to 12V.

I have the switch installed, and the motor hung. Now the question, where to pick up the 12V?

I thought I'd just get my manual out, and see where the optional 12V systems in 1957s picked up the power, and go from that same point. Guess what, evidently all 1957 Fords came with vacuum wipers. So do I try to cut the wires going into the plug at the back of the ignition switch, and pick up my ACC wire there, or do I go out the the ACC side of the starter solenoid?

I considered a 6A fuse holder as quickly as I can pick up my power (meaning near), but also considered a 6A circuit breaker. I'm pretty sure I can order the breaker over at NAPA. I'm thinking I'm going to lean towards the fuse. Mfg says fuse is OK, and breakers while resetting, (may) have different trip charactaristics. I'm always reluctant asking someone behind the parts counter technical questions about parts, unless they are so complex that it makes them pick up the telephone and call product engineering at the manufacturer. Evwen then, you don't know who they are talking to, perhpas it's there technicals Q&A people in some far off place.

I am more interested in getting it right, as opposed to saving time, or a few bucks on electrical goodies. So advice on where to pick up the 12V power feed? Mayber hacking into the original wiring harness isn't such a good idea. It's 1957 harness, but you'd never know it. No one has been under there hacking it up, it's never even had a radio change.

[dmsfrr]

I'd tend go with a circuit breaker for the automatic resetting if nothing else. Who wants to be trying to change an under-dash fuse on the side of the road in the rain.

There is no plug in the wiring for the ignition switch, or ACC terminal on the starter solenoid and you don't need to cut any wires.
Just add another wire (with a crimp-on ring terminal) onto the ACC terminal stud of the ignition switch.
.

[KULTULZ]

MY SUGGESTION

Unless you want a dedicated resto appearance, I would source the power supply straight from the BAT with a relay and proper inline blade fuse.

The diagram below shows a HDL power source routing. The wiper motor would be similar . Have the fuse @ the wiper motor connection for easy service. This method will reduce additional AMP draw on the switch(es).

If you want to see how FORD did it, you will need a 59 FORD ELECTRICAL MANUAL.

[Gene F]

Ya think I need a relay for a max of 6 amps? I'm guessing normal current draw to be abt 1/2 of that.

[KULTULZ]

Originally Posted by Gene F

Ya think I need a relay for a max of 6 amps? I'm guessing normal current draw to be abt 1/2 of that.

What AMP draw does the kit vendor state?

Here's a tutorial on relays- http://www.gtsparkplugs.com/intro-au...ve-relays.html

You might also think about a fusible link rather than an inline fuse mounted @ the starter solenoid. Fairly easy to change and prevents an electrical fire if the feed wire shorts out on the body somewhere.

[bobss396]

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I have the Newport electric wiper motor on my car, no relay. I wired it into the wiper wire off my harness. But a wire off the ACC terminal on the ignition switch would be fine, you could fuse it if you wanted to.

[dmsfrr]

Maybe I'm OCD...
Two reasons I'd wire power to the new wiper motor from an ACC terminal, not Bat terminal...

1. Chances are you won't need the wipers if the car isn't switched on or running.
2. When the ignition key switch is Off, so is the power to (most of) the wiring. There's less chance of an unattended meltdown when the car is parked or put away.

I'm not sure how old the wiring harness in your car is, or if you have wiring hungry rodents in your area but, I disconnect a battery cable before I walk out sight of my '55. Ok not OCD, I must be paranoid.

[bobss396]

The ACC position is the safe option. My OG wiring was so bad, I yanked it all out and went with a new harness. The old one had lamp wire in it, no fuse box. Just inline fuse holders all over.

[KULTULZ]

Originally Posted by dmsfrr

Maybe I'm OCD...

Two reasons I'd wire power to the new wiper motor from an ACC terminal, not Bat terminal...

1. Chances are you won't need the wipers if the car isn't switched on or running.

2. When the ignition key switch is Off, so is the power to (most of) the wiring. There's less chance of an unattended meltdown when the car is parked or put away.

The wiper motor (wiper switch) is keyed through the IGN SW (ACC). It then opens the relay which then supplies BAT VOLT directly to the WM. It allows wiper operation without bringing the AMP draw through the cabin. The WM supply circuit is protected by a fuse/fusible link @ the BAT so there is no chance of a short/fire.

As you add circuitry to an older car, ELECTRICAL the components are not able to handle additional AMP draw as they were not designed for it.

[dmsfrr]

Originally Posted by KULTULZ

. . .
As you add circuitry to an older car, ELECTRICAL the components are not able to handle additional AMP draw as they were not designed for it.

True enough. But if just one add-on doesn't draw too much current you're usually ok. A new wiper motor should draw less current than an oem power seat or window motor, which wouldn't be running at the same time as the wipers. (is that a good excuse?)

But more add-ons than that or for 'safety first', a relay using a 'Battery' power terminal is the way to go.
My OT 4x4 truck has added fog & driving lights powered from relays with individual fuses at the Bat connections. And if my '55 Bird ends up with extra lights in the front bumper guards, they'll be on a relay too.
.

[KULTULZ]

Equate the idea to the horn relay mounted in the engine compartment. Why introduce such heavy additional AMP to the switches?

[paul2748]

For my 54 Ford (converted to 12 V), I just wired the wiper wire to the ignition switch. I don't have hardly any non oem additions to the switch other than the wipers. NO PROBLEMS. And I have used the wipers a number of times.


Unless you have a number of other items other than the oem stuff wired to the switch, the addition of the wipers should not be a problem

[Gene F]

The car was built in 1957 without a fuse box (panel), that's the way Ford made them. Like stated above, inline fuse holders every where. That comment about the power seat is right, my power seat has a 20A fuse, and that baby sure takes some juice. You can see the headlamps pull down when ya flip that switch.


My wiring harness is nice. I think I'm gonna bring a fused wire off the ignition switched side of the solenoid.