oldodge41 Posted March 8, 2020 Report Share Posted March 8, 2020 What is the difference between a 6 volt positive ground regulator and a 6 volt negative ground regulator? I know the difference between positive and negative ground. I just can't think of the reason why the voltage regulator on these old cars would care. I plan to replace mine this spring when I go back to 6 volt from 8 volt and I came across some marked positive ground and some marked negative ground. As to why the switch back to 6 volts from 8 volts? I went to 8 volts some years ago due to some pretty poor wiring and connections. A few years ago I rewired the car and it has worked great. My 8 volt battery has gone kaput, no shame it is pretty old, so I wish to replace with a high CCA 6 volt. When I adjusted my current voltage regulator to support the 8 volt battery I remember thinking "I should probably replace this thing", but I can't remember why. I think my memory went south with the 8 volt battery.... LOL. Anyway I plan to have a new one on hand when I start to adjust the old one in case I remember when I get it open. Neither of these are the one I bought, they are just for illustrative purposes. Quote Link to comment Share on other sites More sharing options...
Doug&Deb Posted March 8, 2020 Report Share Posted March 8, 2020 I don’t think it matters whether positive or negative ground. I believe you have to polarize the regulator before installing. Of course it’s been awhile since I changed one so my memory may be wrong 1 Quote Link to comment Share on other sites More sharing options...
soth122003 Posted March 8, 2020 Report Share Posted March 8, 2020 It has to do with the way the rectifier is wired in the voltage regulator. If you have a motors manual 1935-1953 it is explained in detail on page 51. Joe Lee 1 Quote Link to comment Share on other sites More sharing options...
oldodge41 Posted March 8, 2020 Author Report Share Posted March 8, 2020 Hey, Joe Lee, I do have a Motors Manual that covers my car. Never thought to look there for an explanation. Will do. Thanks........... Quote Link to comment Share on other sites More sharing options...
50mech Posted March 9, 2020 Report Share Posted March 9, 2020 (edited) As I understand it, and I could be wrong as I vaguely grasp the circuitry but... In short ,the generator actually gets polarized , not the voltage regulator ( even though it's done there) . It cares because the relative polarity of the shunt windings in the VR must must be correct with the field in the generator. Shunt windings are grounded to the body of the VR. So basically...shunts are wound or wired the wrong direction on a mismatch....I think. Edited March 9, 2020 by 50mech 1 Quote Link to comment Share on other sites More sharing options...
oldodge41 Posted March 9, 2020 Author Report Share Posted March 9, 2020 Here is what I found on another forum. Back in the day they would switch material on the stationary and moving contacts depending on the polarity. I think they would be interchangeable as far as functionality but service life should be longer on one with correct polarity. "QUALITY mechanical voltage regulators from years ago were often polarity-sensitive, but with the "one size fits all cheaply-made reproductions" probably not so likely anymore, unless specifically noted by the manufacturer. What makes a quality MECHANICAL/vibrating point voltage regulator polarity-sensitive is that they used different materials for the (+) and (-) contacts that were best-suited for that specific use, for long life with minimum metal transfer and pitting. That is the only component of a traditional MECHANICAL VR that is affected by polarity, and even the style with a specific recommended polarity will work on the opposite polarity, but contact life will be shorter." 1 Quote Link to comment Share on other sites More sharing options...
soth122003 Posted March 9, 2020 Report Share Posted March 9, 2020 On 3/8/2020 at 10:24 AM, soth122003 said: It has to do with the way the rectifier is wired in the voltage regulator. If you have a motors manual 1935-1953 it is explained in detail on page 51. 1 Quote Link to comment Share on other sites More sharing options...
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