Positive or Negative ground

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Model T Ford Forum: Forum 2016: Positive or Negative ground
Top of pagePrevious messageNext messageBottom of page Link to this message  By Chester Leighton on Tuesday, November 01, 2016 - 07:56 pm:

A recent thread and a recent assist on a friend's project has raised the question about battery polarity for me again. When I restored my 26, I got three books, black "Model T Ford Service" manual, gold "Model T Ford Owner" and yellow " Henry's Wonderful Model T". Each of the references (except the "yellow" book) shows the battery connection to ground going to the negative battery terminal. A recent posting by Steve Jelf in another thread shows negative ground. However, during the 2015 Mainley T tour a very knowledgeable driver informed me that all model T's were positive ground. Also, a friend recently installed a starter motor on his 1913 runabout and insisted he system was positive ground. My 26 has worked quite well for the last 7K miles with negative ground. Which is it? Did the system change somewhere in the production life of the T?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Tim Lloid on Tuesday, November 01, 2016 - 08:00 pm:

My 26 is negative ground but A models are positive ground.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Tim Wrenn-Monroeville OH on Tuesday, November 01, 2016 - 08:07 pm:

Tim is right, and ALL T's are negative ground unless someone has screwed around with them. I have a model A also, and I wish to God it was negative ground just to keep from messing with my lame brain. But I think I cured that by marking on the trap door to the battery under the floorboard in big yellow letters with a paint pen "POSITIVE GROUND- 6V"!! I already fried one battery charger from this car, don't want to do any more!! :-)


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ron Patterson-Nicholasville, Kentucky on Tuesday, November 01, 2016 - 08:14 pm:

The Model T Ford FA starting and lighting system is Negative ground and, No it never changed during production. .
All Model T Ford's were negative ground!
All Model A Ford's were positive ground.
Both "ORIGINAL" systems will work either way correctly with no damage if you do certain things correctly when converting.
Hence the confusion.
This of course exempts modifications to the original system and then all these bets are off.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Tim Lloid on Tuesday, November 01, 2016 - 08:19 pm:

Tim W.is so right I look at the battery every time after all these years when I put the battery tender on my model A s. Keeps you thinking but its a pain. Tim


Top of pagePrevious messageNext messageBottom of page Link to this message  By charley shaver- liberal,mo. on Tuesday, November 01, 2016 - 09:16 pm:

ford stayed with pos ground tell 56 when they went to 12 v. charley


Top of pagePrevious messageNext messageBottom of page Link to this message  By Norman T. Kling on Tuesday, November 01, 2016 - 09:19 pm:

The T came with negative ground. Some times someone might install an alternator or other equipment which was made to use a positive ground and so they will turn the battery around. If so you will also need to change the cutout if you have a diode type. I'm not sure the starter will work. Someone in the know will answer this. If you use positive ground, will the starter turn backwards? I do know this that if the battery is turned around the ammeter will point to discharge when the generator is charging.
Norm


Top of pagePrevious messageNext messageBottom of page Link to this message  By John F. Regan on Tuesday, November 01, 2016 - 09:30 pm:

High Torque motors typically have a series field winding and thus they will spin the same direction regardless of the polarity of the power applied. The T starter motor is such a series field motor.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Terry Woods, Richmond, Texas on Wednesday, November 02, 2016 - 01:06 am:

T negative. A and some, if not all V8's in the thirties, positive.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Aaron Griffey, Hayward Ca. on Thursday, November 03, 2016 - 10:54 pm:

All Ford V8 cars were positive ground until '56, including cars of the thirties. Same for 6 cylinder cars.
Chrysler cars were Also positive ground including Studebaker and many others.
GM cars were 6 volt negative ground, except Cadillac until '41.
When American cars switched to 12 volts they went negative ground. All U.S. Cars.
When cars went to alternators they all went to negative ground- including foreign cars.
There were 12 volt systems available on Ford trucks as early as '38. They may have been negative ground, I don't know.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Aaron Griffey, Hayward Ca. on Thursday, November 03, 2016 - 11:06 pm:

When you change the polarity of a car the ignition coil should be reversed.
The generator polarity is changed on T or A by using a jumper wire from battery to field for one second. Flash the field. Just go around the cut out.
On cars with voltage regulators you do it by jumping from battery terminal on the regulator to the terminal next to it.
On a Ford that is batt. To field, on a GM it is batt. To arm.
Flashing to the wrong terminal can kill the regulator, maybe the generator too.
When you have a generator rebuilt you should polarize it before starting the engine for in case it has been polarized backwards.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Aaron Griffey, Hayward Ca. on Thursday, November 03, 2016 - 11:07 pm:

When you change the polarity of a car the ignition coil should be reversed.
The generator polarity is changed on T or A by using a jumper wire from battery to field for one second. Flash the field.
On cars with voltage regulators you do it by jumping from battery terminal on the regulator to the terminal next to it.
On a Ford that is batt. To field, on a GM it is batt. To arm.
Flashing to the wrong terminal can kill the regulator, maybe the generator too.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Larry Smith, Lomita, California on Friday, November 04, 2016 - 09:23 am:

Will this topic ever end?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Harold Schwendeman - Sumner,WA on Friday, November 04, 2016 - 02:57 pm:

Larry,....it seems to me that the one that "never ends" is the HCCT/ECCT "debate"!


Top of pagePrevious messageNext messageBottom of page Link to this message  By Zachary Dillinger - Charlotte, MI on Friday, November 04, 2016 - 04:02 pm:

Clearly, the way to bring about the end of the world is to ask the following: Will a HCCT-tested coil setup on a positive ground work better than a distributor on a negative ground system, and can I use detergent multi-weight oil with MMO in the fuel with either?


Top of pagePrevious messageNext messageBottom of page Link to this message  By George John Drobnock on Friday, November 04, 2016 - 04:13 pm:

For that "Old-Timey" racer's edge smell of Castor oil. What is the ratio of castor oil to gasoline?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Gary Blake, Kansas City on Friday, November 04, 2016 - 06:10 pm:

George....That depends on the engine. If you are talking about a 2 stroke-cycle engine then that could range from between 30-1 and 50-1. For a 4 stroke-cycle engine such as a Model T, then much less Castor oil could be used to get that "old Timey" racers edge smell. Try 100-1 and stand behind your car when idling. I suspect you will notice it. The smell is the un-burned Castor oil.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Dave Hjortnaes, Men Falls, WI on Friday, November 04, 2016 - 07:02 pm:

What about modified bitumen roofing tar?


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