Starter Solenoid Power Terminals and/or upgrade

[jasonmako]

I'm using the stock style fender mounted starter solenoid. Does it matter which copper terminal I connect to batt or starter - are those two studs batt/load agnostic? I want to move mine to a different location/orientation and I'd like to swap the sides the heavy cables connect to.

Also, in a completely non-stock Bronco is there a better/more modern version of solenoid I should use that is perhaps better suited for modern high torque/high current starters?

'77 Bronco, 408W, MSD EFI/6AL/Distributor, Mean Green Starter

 

[Steve83]

That's a starter RELAY; a solenoid would be ON the starter (the smaller cylinder). There is no difference between the 2 large terminals.

(click this text)


But this style is better, for several reasons:

(click this text)


Modern high-torque starters draw LESS current than the older ones, so a heavier relay is not necessary.

 

[Oldtimer]

Is the "I" terminal wired to one of the large studs, or is it powered by the disc that connects the two large studs when the coil is energized?

 

[DirtDonk]

Good question. I’ve had them apart before but can’t remember how it’s wired internally.

 

[904Bronco]

I - is powered when the relay is closed and the starter is engaged, it should be powered by disc. My Thoughts are - If it was to the studs, since they are not marked and it doesn't matter which one you use, then if it was attached to the stud the Batt is attached to, it would have power full time.

 

[DirtDonk]

I agree it’s probably contacted by the disc.
Don’t see how it could always remain isolated otherwise.

 

[jasonmako]

That's a starter RELAY; a solenoid would be ON the starter (the smaller cylinder). There is no difference between the 2 large terminals.

(click this text)


But this style is better, for several reasons:

(click this text)


Modern high-torque starters draw LESS current than the older ones, so a heavier relay is not necessary.

Cool, so the takeaway is buy one of the pancake style 80s relays. I prefer that form factor/design for my application anyway, so I like that option.
And the batt/load terminals are agnostic which way I wire them.
Thanks!

 

[jasonmako]

That's a starter RELAY; a solenoid would be ON the starter (the smaller cylinder). There is no difference between the 2 large terminals.

(click this text)


But this style is better, for several reasons:

(click this text)


Modern high-torque starters draw LESS current than the older ones, so a heavier relay is not necessary.

I noticed in the bottom left photo of the late-style that the white cylinder states coil & DIODE. If that's the case then it does matter which of the two large terminals the battery connects to as current can only flow in one direction. Unless that diode is on the control circuit.

 

[Oldtimer]

If you dive into Steve's link you will find the diode is connected to the "S" contact (to keep EFI computer's happy).
So the battery / starter studs are agnostic.

The disc does indeed contact "I" terminal in both style relays.

Jason, You may need a pancake style relay with the "I" terminal.

 

[jasonmako]

If you dive into Steve's link you will find the diode is connected to the "S" contact (to keep EFI computer's happy).
So the battery / starter studs are agnostic.

The disc does indeed contact "I" terminal in both style relays.

Jason, You may need a pancake style relay with the "I" terminal.

Oldtimer, Thank you for the clarification that the diode is on the trigger circuit. I have a full MSD setup and custom wiring harness, so I have no need for the I terminal in my configuration.

 

[Steve83]

Is the "I" terminal wired to one of the large studs...?

It's visible in the top right panel of that pic.

...the white cylinder states coil & DIODE. ... Unless that diode is on the control circuit.

Yes, the coil is what triggers the relay - not on either large terminal.