Positive earthed..???

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Dougie212
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Positive earthed..???

Post by Dougie212 »

Hi there,

So, bare with me… I’m new to this.

I have a 1958 Morris Minor 1000 that I collected last week.
I was having a little look this morning and noticed the battery terminals were loose. So, tightened them and realised the negative terminal is connected to the main loom of the car and the positive is attached to earth.
I’ve attached a few pics but believe I have an old dynamo fitted still so would this mean that the car is positive earthed?
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Thanks
Duncan
myoldjalopy
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Re: Positive earthed..???

Post by myoldjalopy »

Yes, positive earth - just as it was originally.
Dougie212
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Re: Positive earthed..???

Post by Dougie212 »

Perfect, thankyou ‘myoldjalopy’!
simmitc
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Re: Positive earthed..???

Post by simmitc »

For originality, keep the positive earth. Many people convert to negatives earth so that they can more easily fit modern accessories, but the choice is yours. You'll find plenty of discussion about the choices.
Dougie212
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Re: Positive earthed..???

Post by Dougie212 »

Hi simmitc..

Definitely keeping it original.. my whole thought process when taking on this little project of a car was keep everything as original as possible..
islecastle
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Re: Positive earthed..???

Post by islecastle »

Way back in the 60s, there was a lot of correspondence about positive earth corrosion which is why most manufacturers had changed back to negative earth by the end of the decade.
It's easy to change over either way with no new parts needed apart from battery terminals.
1973 Ford Cortina Mk3
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JOWETTJAVELIN
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Re: Positive earthed..???

Post by JOWETTJAVELIN »

Worth mentioning that the ‘earth’ terminal should be open braid to clearly identify it as such. Your battery cables have been replaced. Originally would have been Lucas ‘helmet’ type.
les
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Re: Positive earthed..???

Post by les »

There is a book called the Original Morris Minor if you’re into originality. I see a few things in your pictures that deviate from original specification, if you don’t mind me saying, of course. :D

oliver90owner
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Re: Positive earthed..???

Post by oliver90owner »

Les is right.

For a start, the battery clamp 9which does not look to be original) should be over the top corner edge of the battery - to prevent movement in the vertical, as well as in the horizontal plane. This is likely due to the wrong battery being installed, with the risk of the battery stay contacting the live battery terminal connector.

I certainly wouldn’t bother about braided earth straps unless they were original and originality was desired. It is a bit difficult (for most of us) to mistake the positive and negative terminal connectors, although it would clearly seem to be needed by some.

Dynamos are not polarity sensitive but do need polarising if they are good, but fail to charge. Coil connections need to be the correct way round, depending on the polarity chosen.

The live lead may be susceptible to chafing, if is actually touching the battery box lip.
myoldjalopy
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Re: Positive earthed..???

Post by myoldjalopy »

Well, the OP has said he would like to keep it "as original as possible". In theory, it would be possible to change every single thing back to the original spec. But I suspect he really means he doesn't want to put in modern seats, wide wheels, servos, disk brakes, lots of added dials and switches, electronic ignition etc. My SII is certainly not original - it has a 948cc engine and gearbox (although the box is a hybrid one that keeps the interior looking original), at some point it had 'period type' flashers fitted although retaining the trafficators as well, 8" front brake drums, the later rear wings etc. Oh, and it had a re-spray about seven years ago. But to the untrained eye, it looks like a genuine, old Morris Minor, not some kind of Frankenstein's monster. In other words, the alterations are pretty discrete and the operating systems are standard. Truly original cars are rather rare now, especially the earlier versions.
Dougie212
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Re: Positive earthed..???

Post by Dougie212 »

Thanks for your replies everyone.

Yes, so this is my first venture into owning a classic car and so yes, I’d like to keep things as original as possible by way I won’t be putting any modern additions in it, more replace tired and worn out parts with used or good quality pattern parts and restoring things to like original fittings that may have been changed - like the battery clamp it now appears.

Out of interest, what in the pictures is different to how they would have been when the car was originally built please?

Thanks

Duncan
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Re: Positive earthed..???

Post by JOWETTJAVELIN »

Image


I have taken this photo from google/Adrian Flux of a restored car, as a good guide for you. And you will see the type of battery cables fitted, with braided earth, that in spite of some people who never get their wires crossed and think they know better than real engineers, is nevertheless a fact that is what the cars originally came with, by and large. Regardless of what some people (wrongly) think, it is established practice that electrical polarities be clearly distinguished from one another.
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geoberni
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Re: Positive earthed..???

Post by geoberni »

Round battery posts are different diameters for POS and NEG posts, and have been for many decades, but exactly when the system started, I don't know.
Posts are something like 17.9mm and 19.5mm, the Positive being the larger one.
That worries me when I see spares suppliers offering pre-assembled cables and they don't state if it's POS or NEG terminal fitted.

The Lucas Cap Connectors were certainly identified as +/- but from when.... I've no idea.

Was it originally a braided cable for the earth? Probably, but they weren't the flat type that are common now, they were round as you can see in JJ's image. If you look very closely, you can see those Lucas connectors are marked + & -.

My car has a solid earth cable looking exactly like yours with the clamps, but it is NEG earth. Those clamps are easy to change over, unlike the soldered Cap type.

As to originality, to be really pedantic, it would have had a battery with exposed Cell Connections, but that's not really a great idea under a bonnet.
It's very easy to short it out with a spanner carelessly place in haste.
They are very expensive too, just for 'originality', 2-3 times as much.
Search for '12v Hard Rubber Classic Car Battery' and you'll see they are £150-£250 each. :o

If you do keep it POS Earth, be very careful if you ever need a Jump Start :roll: :wink:
Basil the 1955 series II

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