Starter Wiring, Why doesn't my car look like all the others?!? Options

[Spoke]

Found this schematic for the Ford relay conversion.

[Superhawk996]

How much current does the original solenoid draw actually?

25A at ambient temperature.

[Superhawk996]

In response to OP original question - you’re going to have to trace the wire. There are no OEM stock wires exiting directly out of that area of the bulkhead. Some one did a “custom” job.

[chmillman]

How much current does the original solenoid draw actually?

25A at ambient temperature.

The solenoid or the starter...??? I can't imagine the solenoid taking 25A...

[Superhawk996]

The solenoid or the starter...??? I can't imagine the solenoid taking 25A...

Solenoid

I’ve measured it with an accurate shunt resistor.

There is a reason the yellow solenoid wire is large (4.0mm^2 area) which is approx an 11 AWG size.

[chmillman]

I’ve measured it with an accurate shunt resistor.

There is a reason the yellow solenoid wire is large (4.0mm^2 area) which is approx an 11 AWG size.

OK, interesting, learned something here. I went and looked at the 914 manual and I see that the 'solenoid' is not only actuating the relay contacts in this case, but also pushing the starter drive shaft to engage the flywheel. Which I guess could explain the large current draw.



And, it actually says it could draw up to 35 amps...



This instead of the typical inertial Bendix mechanism that is used for example on my '57 Ford T-Bird - there the 'solenoid' just is a relay to switch the starter motor current. It's actually the exact same one you're proposing to mount on the 914 - the design hasn't changed from the '50's... I looked and it draws 'only' 8-10 amps. That's still a fair current draw for a relay, but it's electromechanical (not solid state) and according to my T-Bird manual designed to switch up to 500 amps.

So, if I understood correctly, you're using this Ford solenoid as a relay to switch current to the 914 'solenoid' - as that still needs to function in order to engage the drive gear - you're not bypassing it altogether. So you're switching ~25-35A with a solenoid built to handle 500... and which still draws 8-10A. Not better to use a solid-state diode-protected 50A relay - which draws a fraction of an amp instead?

[emerygt350]

The amperage is only part of the issue. The Bosch solenoid is 12v and sensitive to it. The Ford solenoid hasn't changed since before your thunderbird and it only needs 6v. So as the wiring gets old and the distance traveled starts hurting it, the Ford doesn't care.

[Superhawk996]

The amperage is only part of the issue. The Bosch solenoid is 12v and sensitive to it. The Ford solenoid hasn't changed since before your thunderbird and it only needs 6v. So as the wiring gets old and the distance traveled starts hurting it, the Ford doesn't care.

This whole Rube Goldberg extra solenoid thing has become a religion just like oil.

I get what you’re saying but the simple fact is Ohms law always prevails.

To the point chmlman made, there are far better modern solid state choices than a Ford solenoid if the concern is low voltage and minimal current draw across the ignition switch.

If there is 6v on the yellow solenoid wire (ever) there are far deeper issues that need to be addressed before adding more complexity and wiring to the system. (IMG:style_emoticons/default/stirthepot.gif)

[chmillman]

If there is 6v on the yellow solenoid wire (ever) there are far deeper issues that need to be addressed before adding more complexity and wiring to the system. (IMG:style_emoticons/default/stirthepot.gif)

Yeah, that was pretty much what I was going to reply... (IMG:style_emoticons/default/beerchug.gif)

That being said, I do now see the real usefulness of a relay (whatever kind you choose) to unload the ignition switch contacts. I had no idea the solenoid itself draws 25A or more...

Going to be one of my near future projects, I think I will go with a solid-state unit installed in the engine bay. Maybe 3D print a neat enclosure. Have to see where it could go.

[emerygt350]

Many of us went from intermittent no start (as in the solenoid would not even clic), to works every time with that solenoid. With no other changes.

[chmillman]

Many of us went from intermittent no start (as in the solenoid would not even clic), to works every time with that solenoid. With no other changes.

Yes, but any kind of relay would probably produce the same result in that case. Simply a remedy to get full battery voltage directly to the existing solenoid instead of going through the car wiring system up to the ignition switch, through the switch contacts and back out to the solenoid - where there obviously is some resistance at one or more points in that long path that is causing loss of votage/current. That's all your Ford solenoid does.

[emerygt350]

Many of us went from intermittent no start (as in the solenoid would not even clic), to works every time with that solenoid. With no other changes.

Yes, but any kind of relay would probably produce the same result in that case. Simply a remedy to get full battery voltage directly to the existing solenoid instead of going through the car wiring system up to the ignition switch, through the switch contacts and back out to the solenoid - where there obviously is some resistance at one or more points in that long path that is causing loss of votage/current. That's all your Ford solenoid does.

And it is built like a tank and 8 dollars if you have to buy it at all. I used the old one off my mustang.

[914werke]