horsefeathers 15 #1 Posted April 14, 2011 I was talkin' with some buddys and the topic of positive ground systems came up! Many years ago I had a Triumph chopper w/ positive ground system. Soo... How does a positive ground differ from a negitive ground?? How does it work? Doesn't relate to tractors... but intersting! HORSEFEATHERS! Share this post Link to post Share on other sites
rmaynard 14,865 #2 Posted April 14, 2011 I had a friend with a Triumph TR3 back in the late 1960's. It had been brought over from England. When he got it here, the first thing that I noticed was that it had the (+) battery terminal hooked to ground. We asked a local "foreign car" dealer about it, and he said that in England, where the humidity is constantly higher, they would wire cars with a (+) ground to prevent corrosion of the electrical system. I don't know how this works with DC motors such as a starter, as I always thought that reversing the polarity made them run backwards. :thumbs: Share this post Link to post Share on other sites
pfrederi 17,129 #3 Posted April 14, 2011 Most all farm tractors up until the late 50s used positive ground. Many cars used it also up to the 50s. To convert you had to reverse the wires on the coil and depending on your charging system change the voltage regulator and flash (polorarize) the generator. Didn't have to do anything to the starter motors. Share this post Link to post Share on other sites
mavfreak 11 #4 Posted April 14, 2011 I worked on a couple of MG's with the positive ground. rmaynard is right as far as I know cause I heard the same thing. I think all the motors are wound for the way they ground. As far as working on them. Well IT SUCKS! Positive ground lucas wiring makes you want to jump off a bridge, at least it did for me. Share this post Link to post Share on other sites
pfrederi 17,129 #5 Posted April 14, 2011 The corrosion thing may be part of it. Positive ground actually makes more sense to me as the electrons flow out of the negative terminal to the switch then to the load then to the frame of the vehicle and back to the positive terminal. (at least I think that is how it works)...Where is SOI :thumbs: Share this post Link to post Share on other sites
Save Old Iron 1,563 #6 Posted April 14, 2011 Sorry guys, I just got back from the dedication in my honor at the Guggenheim in Manhattan. The exhibit is "SOI on the Half Shell" and I encourage anyone in town to check it out. Our views on what is better for man and machine tend to change over the years. About the time positive ground lost all favor in the automotive world, this ad was in its heyday "T" zone indeed! T for tracheotomy maybe ! Better to bet your lunch money on something a little more consistent. Elements on the right side of the chart love to steal and use other elements electrons - CL and O (chloride and oxygen) Elements on the left side love to "give up" their electrons. LI (lithium, as in hi capacity lithium ion battery) is very "trusty" and allows other elements to use its electrons. So as you move to the right of the chart, metals get less "trusty". So less trusty - less rusty. Fe is iron and Al is aluminum - so you start to get the whole position versus "rust potential". My point here is regardless of positive or negative grounds in England or Africa, Oxygen combines with Iron and steals electrons from the metal element (pits the metal). Water droplets tend to concentrate oxygen molecules in "spots" on the surface of the metal and promote increased oxidation activity in these "spots". If positive ground were a good thing and more effective than paint and plating, we would still be using it. So, giving up electrons - pitting - like points pitting - like spark plug electrode pitting, does erode metal also. Some folks back in the early days noticed negative side metal contacts eroded less than their positive counterparts. Both in points and spark plugs. To make the center electrode of a spark plug last longer, the threads of the spark plug where made positive in respect to the center electrode. So positive threads on the plug = positive connection to the engine block and viola - positive ground was born. When spark plugs and points only lasted 10,000 miles, there may have been some perceived advantage to positive ground. With current spark plug technology and no points in ignition systems - no need for positive ground. From the corrosion aspect - positive ground falls way short of the protection given by galvanized metal and modern day paints. Share this post Link to post Share on other sites
chazm 412 #7 Posted April 15, 2011 I must say SOI, you are one SASOB Is there no end to your wealth of knowledge... or squirrels :D Share this post Link to post Share on other sites
Horse-Drawn 1 #8 Posted April 16, 2011 WOW... Nice lecture on Positive Ground. Much better than my dad's when I asked him 25 yrs ago. "It's crap & things didn't last very long" was his version of it. LOVE the squirrels! They just became the background on my laptop! ...Can't wait until the wife (squirrel lover & protector of all things furry & cute) finds it :D Share this post Link to post Share on other sites
