Replacement generator cut-out options

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Model T Ford Forum: Forum 2018: Replacement generator cut-out options
Top of pagePrevious messageNext messageBottom of page Link to this message  By John Chady on Monday, June 25, 2018 - 10:34 pm:

Why can't I find a Model T 6V positive ground replacement cut-out? They are all listed as negative ground. There are some Model A positive ground cut outs listed, would those work for my 24 T?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Steve Hughes, Raymond, NE on Monday, June 25, 2018 - 10:49 pm:

We just had another thread on this same subject. Model Ts are negative ground cars. That is how they came from the factory. Instead of looking for a non-standard positive ground cut-out, just turn the battery around and connect the negative terminal to ground.

If you insist on keeping the car positive ground, the standard Model T cut-out doesn't care if the car is connected positive or negative ground.


Top of pagePrevious messageNext messageBottom of page Link to this message  By John Chady on Monday, June 25, 2018 - 11:06 pm:

I was told the car was positive ground, but may have been bad info. I have had the battery hooked up positive ground since I've owned it. Fried 2 batteries, melted the cut-out, lost my magneto. Could all this have been caused by reversed polarity?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Aaron Griffey, Hayward Ca. on Monday, June 25, 2018 - 11:37 pm:

The cut out is a switch that turns on when the generator is charging and off when it ainít.
It does not give a ratís butt if the electricity is negative ground or positive ground.
Just put the battery in, connect the cables , polarize the generator and run the car.
Next we will have guys telling us they canít find any negative ground light bulbs.how about some negative ground battery water?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Garnet on Tuesday, June 26, 2018 - 12:48 am:

A good starting point would be to verify your wiring John. The only way to kill the internal magneto is by very high heat ... or by wrongly applying dc current to the magneto terminal on the transmission cover. Loose wires on the ignition switch can also cause this when an errant magneto wire touches a battery terminal or vicey versey. Incorrect wiring can cause it too. Regarding the fried batteries, were they boiled dry or did they just go dead. More clues are needed.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mark Gregush Portland Oregon on Tuesday, June 26, 2018 - 01:20 am:

All Fords from 1928 to the introduction of 12 volt system were positive ground. The standard mechanical cutout does not care what way the terminals of the battery are connected. Now it's a diode or more fancy type, yes then it need to be made for positive ground. Snyder's carries positive ground types in the Model A section.


Top of pagePrevious messageNext messageBottom of page Link to this message  By kep on Tuesday, June 26, 2018 - 03:20 am:

Only diode types have a polarity.
Sounds like your ignition switch might be in need of attention.


Top of pagePrevious messageNext messageBottom of page Link to this message  By John Chady on Tuesday, June 26, 2018 - 04:21 am:

Thanks for the advice Aaron. If it didn't matter, then the suppliers should list them as such. It would stop questions like mine.

Batteries were still full of water, I did not check acidity? But it seems one cell was dying, I could only get 60% charge with my charger on both batteries. One battery only lasted 3 days of driving. Now after disconnecting the cutout and generator, the new battery has lasted a week and fully charges.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Martin Vowell, Sylmar, CA on Tuesday, June 26, 2018 - 04:25 am:

The Model A cut out is the same as the Model T cut out...what you use for ground makes no difference to the cut out it works regardless which polarity you use. But your T should be negative ground, not positive ground and if you've got it grounded the other way round, that may be why you're having problems...not with the cut out, but with the generator.


Top of pagePrevious messageNext messageBottom of page Link to this message  By John F. Regan on Tuesday, June 26, 2018 - 10:48 am:

Martin:

Most of the common cutouts for sale now for T or A are DIODE type and they DO CARE whether the car is positive ground or negative ground in order to work right. The car battery polarity MUST match the cutout polarity if the cutout is a diode type. Now the older Mechanical cutouts used for T and A were NOT polarity sensitive and can be interchanged between positive ground and negative ground systems with no regard for polarity issue.


Top of pagePrevious messageNext messageBottom of page Link to this message  By John Chady on Tuesday, June 26, 2018 - 10:54 am:

So, how do I know if my car is positive or negative ground?


Top of pagePrevious messageNext messageBottom of page Link to this message  By John F. Regan on Tuesday, June 26, 2018 - 11:04 am:

Look at the battery connections and see which post is connected to the car frame or motor block. If the negative post is connected to the frame or engine block then that is a negative ground installation.


Top of pagePrevious messageNext messageBottom of page Link to this message  By John Chady on Tuesday, June 26, 2018 - 12:07 pm:

Ok, I know that but how do I know which way the battery should be hooked up. To prevent damage to the generator.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Hal Davis-SE Georgia on Tuesday, June 26, 2018 - 12:18 pm:

Hook it up negative ground. Flash the generator. Without starting the car, turn on the headlights and see which way the ammeter goes. If it goes positive, swap the position of the two wires on the back. You are now in business providing none of your components are faulty.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mark Gregush Portland Oregon on Tuesday, June 26, 2018 - 12:22 pm:

ALL Model T's from the factory were negative ground, All Ford's from 1928 to introduction of 12 volt system were positive ground. Not knowing what cutout/regulator you have installed or what has been done to the car we can only suggest what should be. It would not be a first to have a T with positive ground nor would it be a first to have later cars with negative ground. What is assumed in the catalogs is things are as they came from the factory and what might be common knowledge for many might not be for others.

As was said; cars with mechanical cutouts (having points, original style) do not care what ground is used.

Cars with diode or something like Fun Project regulator has to be matched to what it they were made for, positive or negative ground.

Chances are the person that told you it was positive ground only worked with later 6 volt cars and assumed that ALL Ford cars were positive ground. Not all that uncommon to happen.

Is your wiring in good shape or is it a tangle of wires? Do you have a copy of a wiring diagram, there are a number of good ones on the web? Sounds like there are other issues here, maybe not related to +/- ground.


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