Positive/negative ground 1930 Hudson

4Hud

I am replacing the battery in my recently acquired 1930 Hudson but I don't have any info. It was hooked up as negative ground. I am guessing that is correct.
Our 1936 and up Hudsons are positive ground and the wiring diagram for 1926 shows negative ground. When did the changeover take place? Thanks. Bob.

Geoff

Definitely negative ground for 1930. Change to positive ground was 1934.
Geoff

4Hud

As we say here in Canada, "Thanks eh".

hudsontech

4Hud there are several 1930 manuals in the online library in the Manual file. And several good itmes in the 1930-1939 Reference sheet file.

See URL below for the library.

Hudsonly,
Alex Burr
Memphis, TN

[Deleted User]

Out of curiosity, why did they change from neg to pos gound? And why are most manufacturers using neg ground today? What are the reason for using pos ground and vice versa?

hudsontech

If I remember right electrical theory at one time said that current flowed to the negative terminal. For some reason that changed at some time in the 30's saying actually current flowed to the positive terminal to ground. Not being an electrical engineer what do I know. In electron theory it flows from negative to positive but Benjamin Franklin thought that it flowed from positive to negative, and, of course, old Ben was never wrong.

Hudsonly,
Alex Burr
Memphis, TN

Geoff

Positive or negative ground - reasons for, opens up a whole can of worms, with various theories and arguments for and against both systems, such as chemical reaction between terminals, electron flow versus current flow, rust potential, etc. etc. What it boils down to is it doesn't really matter much except for certain polarity sensitive components such as radio and voltage regulators. Most regulators fitted to Hudsons from 1934 on were positive ground only, and have dis-similar metals in the voltage coil points, and if fitted with the battery reversed will eventually burn out the armature point in the regulator. And of course the radios are polarity sensitive as well, so will not work if battery reversed. Coils also must have negative and positive low-tension terminals connected correctly, with the positive terminal connected to the distributor on a positive ground system. Contrary to popular mis-conception, the starter motor and gauges will not go backwards if the battery is reversed, but the ammeter, if fitted will read the wrong way. After around 1957 all automotive systems were negative ground, to fit in with all other appliances and electronics.
Geoff

[Deleted User]

Another question!
My 39 was converted to 12v neg ground. And as i want my car like it was original (i dont care about that the car will be harder to start and lights will not be as good, i want it to be like the car was built and meant to be at the time) i have heard from some people that the starter will need some work for the conversion from 6vpos to 12v neg, but some people say that nothing has to be done. I think that noone has done anything to my starter. My concern is that i do not know if anything has been done, or if i have to do somethink with the starter with the conversion. Are there more things i need to tripplecheck with the conversion? I know that most parts are not polarity sensitive, and those who are i just need to think a bit more when connecting.

bob ward

When cars are converted from 6V to 12V sometimes the starter is rewound for 12V and sometimes they are left as 6V. A quick way to tell what you have is to connect the starter to 6V and see if it will turn the engine over.