Morris Minor Owners Club

hello , i have a 1964 positive earth moggie and am wondering which is the best way to fit a cigar lighter , i have an illuminated lighter and wonder which is the best place to wire it in to . thanks

Easy enough to fit but as per the post above yours, you will need to change the polarity of your car to negative earthed in order to fit a cigarette lighter socket.

Follow the links in this thread for details of how to change polarity & fit the socket: http://www.mmoc.org.uk/viewtopic.php?f= ... te+lighter

It will be fine positive earth - if all you want to do is light cigs........ But it won't charge a sat nav etc unless -ve earth.

Well even though my car is -ve earth I didn't want a panel fitting lighter socket for my satnav, so I used a socket on flying leads and ran the cable through the back of the drivers cubby box so the socket on its flexible cable just lives in there and I can plug the satnav or tyre pump, phone charger whatever into it. Works fine and doesn't need any brackets or holes you could do the same if you want to leave the car +ve earth and just make sure the lead from the centre electrode in the socket is wired to the +ve supply - just an idea

I also think the general change to -ve earth was to do with electrolytic corrosion by the way, so it would in the long run not be a bad idea to swap

Regarding the Positive / Negative situation relating to corrosion.

Cars were originally fitted with Negative earth systems but it was found that chassis/bodywork corrosion was taking place and it was considered that the problem was not helped by having Negative earth systems so by manufactures changing to a Positive earth system on the majority of cars the corrosion effect was reduced. I believe this change took place in the late 1940's but I am happy to be corrected.

Negative earth systems really only came back into fashion as a result of the need for more electrical power on modern cars. Alternators generate power with a Negative earth and rotate at higher revs which brought its own problems and so as night follows day modern cars now have Negative earth. Yes you can change a dynamo to negative earth if required so as to power new equipment i.e. sat nav but there is little point in doing so other than for the aforementioned point . A dynamo will put out the same power whether it has Negative or Positive grounding. If you do change the polarity make sure that there is a warning sticker regarding the earthing placed somewhere conspicuous so that other people are aware of what has been changed.

Modern cars do not seem to suffer the same effects of corrosion as the old cars so the problems of whether to use Positive or Negative earth in relation to corrosion really does not need to be taken into consideration.

Now here is a thought put a sacrificial diode on the underside of the car as is fitted on boats/ships and maybe the corrosion problem will be resolved. No doubt someone has already done that and any info/feed back gratefully received.

Alternators were only made -ve earth to suit -ve earth cars! Indeed - early 11AC alternators were +ve earth to suit the cars of the day ..... Old cars are ALL +ve earth (unless swapped over by owners) which was the original standard. The -ve earth came in later - and IS to do with reduced electrolytic corrosion of the body... Having a socket wired wrongly and flapping about in the glovebox is all very well - but will come to grief someday............ Make sure it is fused on the non-earth supply line to cope with that.....

make sure that there is a warning sticker regarding the earthing placed somewhere conspicuous so that other people are aware of what has been changed.

It will need to be even bigger and clearer if the car is still positive earth, it's unknown these days except by specialists.
Virtually any modern kit will be knackered instantly, no warnings, just dead, if it shorts or gets the wrong polarity.

My 1935 morris 8 is negative earth from new

Surprising - because I had 3 X Morris 8E and they were ALL +ve earth.

Morris 8 Series 1 1935-1937 were negative earth up until at least 1936 and possibly till the end of Series 1 production.
See 'e' bay item 171064740980 for an under bonnet picture which shows the 1936 Morris 8 Series 1 fitted with negative earth polarity.
The Morris 8E 1938-1948 may well have changed to positive earth polarity somewhere along its production run but have been unable to find a change over date. All under bonnet Morris 8E photographs viewed so far are not clear enough to determine the battery polarity.

cheers for all advice chaps , will have a think about what to do with the cig socket