Location for a cutoff switch and starter draw

[Dennis_Brown]

The 23 coupe I recently acquired had a cut off switch under the driver's seat that had failed from a load when the plastic base melted, it is also going to be a pain having to lift the seat or reach into the trunk to get to it to operate it .
I have a good quality switch to replace it but was thinking about putting it behind the left splash apron on a bracket attached to the frame. I may have to get on a knee to reach under to get to it, but it would be high enough to be in a fairly dry area.
Any comments appreciated.
I am also putting a 6 volt starter solenoid on it using the foot switch to trip it. Reworking some battery cables as the starter does not turn the engine over very fast. I put a woven strap from the frame to the hogshead and no change.
One question I have on cables and draw. The cable from the battery to the solenoid appears to be a 1-0 size. The cable from the switch to the starter is just over 2 feet long and smaller than 1-0 in size.. could my starter problem be located there. The ground cables are 1-0 in size.

[Humblej]

The original 6v Ford starting system works great when everything is in specs. My advice is to yank out all that new stuff and return to original...no cut off switch, no solenoid, no local auto parts battery cables. If your 100 year old starter still turns slow like a tractor with a dead battery your starter needs a rebuild, if your starter has never been rebuilt it needs a rebuild, if your starter was repaired by a previous owner it needs a rebuild, and by rebuild I mean buy one from a reputable model T starter/generator rebuilder.

[TXGOAT2]

The ENTIRE starter motor circuit must consist of quality, heavy gauge material, and all ground points must be clean and tight. Any weak link will degrade performance of the entire system. That's true whether the system is original Ford or an improved system.

A cheap or undersized battery is no bargain,, and neither are cheap or undersized cables, switches, et cetera.

[DanTreace]

For 6v starting, the battery to switch and switch to starter cables must be 0 gauge or known too as 1/O gauge , they are appx 1/2 inch thick. Don’t use premade 12 volt cables you will have problems starting. The ground cable preferably should be a woven strap.

Have tested or new battery, have all cable contact points cleaned to bare metal, esp. all grounds.

Remove the cut-off, it’s just a trouble maker. A solenoid is optional, mounted satisfactorily , (use O cables ) and frame mount the solenoid for it to be grounded.

For best safety, add a fuse to the yellow wire from the switch 6v hot terminal, mounted in line near the switch, but mounted in line near the terminal block is easy access, for disconnecting 6v hot to the chassis when working on dash, lamps, or other 6v items on the T. The fuse will save the T from rare but can happen shorts to the wiring, which will smoke wires and start fires.

[Craig Leach]

Hi Dennis,
I put mine on the ground cable @ the frame. Use a good switch like a Cole Hersey that has a positive detent. Yes hard to get to but shuts of
everything.
Craig.

[TXGOAT2]

Starter draw should be 200 amps or less. Electric starters typically have a duty cycle of 10 to 15 seconds. Don't grind the starter for more than 10 seconds. Less is better. If the engine won't start in under 10 seconds of cranking, stop cranking and find out why. The starter should rest for a minute or two between consecutive starting attempts. A well charged battery of adequate size is essential to good starter performance and long starter life.

[JohnH]

starter_current.jpg (60.17 KiB) Viewed 329 times

[TXGOAT2]

Not clear what the test consisted of.

[J1MGOLDEN]

That Master Switch came in real handy for me once.

Sometimes, I would put my feet back and kick the starter switch.

I kicked it once too often and the rivet on top came lose to let the switch engage when the part came lose.

That engaged the starter, while I was driving at about 35 MPH.

It was easy to kick that master switch in front of the seat riser and shut the starter down.

Then, I just had to take the wire off, and hand crank the car the rest of the day.

[J1MGOLDEN]

Dan, I did not make any friends when I got a copy of the original blueprint from the Ford Archives in Michigan and posted the information. 0 Gauge, AKA 1/0 Gauge, was what was on that blueprint.

When the Model A first came out, it was upgraded to 00 Gauge, AKA 2/0 Gauge and about a year later the specification was changed back to 0 Gauge, AKA 1/0 Gauge.

[big2bird]

1/0 is fine for 6' of cable.

[big2bird]

OIP-3.jpeg (60.31 KiB) Viewed 136 times

[DanTreace]

by J1MGOLDEN » Sun Oct 12, 2025 10:57 am

Dan, I did not make any friends when I got a copy of the original blueprint from the Ford Archives in Michigan and posted the information. 0 Gauge, AKA 1/0 Gauge, was what was on that blueprint.

Jim


Oops, my mistake! I messed up and posted 2/0 or 3/4" thick.....wrong. (Just edited that post to correct it).

You have the factory info, so the cables should be 1/0.


I checked an old Ford battery negative ground cable, Part # 5049B, Factory No. T-1890B that I pulled off a '23 chassis. This cable was used from 1919 to 1923, then Ford went to a ground solid flat strap (woven can be used too)..... This cable is 9 15/16" long, and I measure the OD as .500". The inside wires ID measure .0419".

For ref, modern 1/0 is called to as .035"-.038" ID, and OD of 0.500"

Lang's vendor version of battery cable to starter footswitch.

[henryford2]

what is the value if a "woven" battery ground cable?

[DanTreace]

what is the value if a "woven" battery ground cable?

From a mfg. source:

Ground straps are braided by interlacing multiple strands of flexible wire. Braiding creates a structure that is thicker and stronger than non-interlaced wires and that will resist twisting under load. Compared to a battery cable, a ground strap braid provides greater resistance to breaking. During manufacturing, flat electrical braids that started as tubular braids are flattened with a pressure roller for increased surface area.

The flat braided cable in a ground strap is made of tinned copper wires that improves electrical conductivity and corrosion resistance.

For the twisting the Model T chassis does the ground between the battery and frame benefits with a flexible woven strap that is more easily placed by bending the twists and turns needed to fit from the frame to the top of the battery post.

Once read that electrical theory held the negative electrons flowed ‘over the connector surfaces’ , if true, then a wide woven strap would assist!