Battery Cables Help

[snolan1]

Looking for some advice on the length of the PO & Neg cables I assume positive goes to the starter whast the stock location for the negative could someone post pictures.

Info Needed
Neg Length = ? (Connect location)

Pos Length = ? (Connect location) Starter?


THANKS

Steve

[dbrick]

The negative from the factory is a pretty complex piece, but to duplicate the function, run a heavy 4ga cable from the battery to the engine block/smog bracket, then a short wire from there to the alternator ground terminal. Most people add a heavy ground strap from the starter mounting bolt to the frame, I would add a heavy wire, at least 8 gauge, from the engine or frame to the body. The Positive cable goes from the battery to the starter. While you are there, carefully examine the other wiring that goes down to the starter, that harness can get pretty deteriorated over time.
I usually get my battery cable from a marine supply store, higher quality copper and very flexible, BoatUS and WestMarine have online stores.

[sports imports]

The roadster did originally come with a ground wire from starter bolt to frame.

Ross
sports imports

[One Way]

I ran a short 4 GA black ground cable from the starter mounting bolt to the frame. Looks nice and should be much better than the cracking 8 GA ? that was originally on the car. Also used 4 GA on both of the battery posts. Ran those cables through some wire loom which looks real nice and does offer a bit of protection to the cables. Also suggest installing a rubber boot over the positive cable end at the starter solenoid post. The previous posts offer great advice. Fresh wiring and terminals may be needed going down to the starter. My abandoned roadster had that harness hacked and spliced quite badly. Replaced with all new wiring back into the dash. Good luck, John-Lugoff, SC.

[Nissanman]

Found a few pics. of my wiring which may help.

Self resetting circuit breaker mounted at the alternator.
The "A" wire is routed to the breaker.



Ground cable, the red in my case, routed to the engine block and a smaller gauge cable to the ground connection on the chassis.


Negative cable, the black in my case, routed around the rear of the engine to be bolted to the starter solenoid terminal.

There is also a ground strap from the starter mounting bolt head to a threaded hole in the chassis, adjacent the starter.


I used a product called Carbon Grease to lube all the fastener threads.
It excludes moisture, prevents corrosion and is conducting.
Used sparingly it is also ideal for all of the engine bay wiring connectors


I wasn't sure all the instrument cases would ground out properly since everything had been painted, so I made up a daisy chain cable to link them all together and then to ground.

Once I determined the required length of the large cables, I got a local auto parts store to cut and crimp lugs to them.
I made all the smaller cables myself with a smaller hand held cable crimper.

[K1200 GT]

So down under, you all use red for neg/ground and black as positive? As we use black as neg./ground and red for positive. Do you have problems reading our wire diagrams?

Rich

[Datsun.David]

Feel like this should be a quiet PM to you Rich... but, you asked... their toilets actually flush in the opposite direction too because of the centrifugal force of the earth...

That, and early cars were positive ground instead of negative ground. Not sure the cut off, but my 65 410 Wagon is positive ground as well...

So, wiring diagrams for the early cars were the same regardless of your continent, or the direction your toilet flushes...

I kill me.

dw

[Nissanman]

You guys!
At least we drive on the CORRECT side of the road not the RIGHT side

About the water draining the opposite way.
Theoretically, you would be right, but the force in question is so weak it doesn't happen. Only when you get a huge weather system does the rotation of the earth alter the wind direction to be opposite to the Northern Hemisphere, e.g. Hurricanes in the north [CW], Cyclones in the south[ACW].

And yes, my car is a '65 SP310 and does enjoy the many advantages of a positive ground electrical system
However the cable length and positioning is identical

[K1200 GT]

So you ask a simple question and you get a smartass answer. Never thought about the positive ground situation. I have had 54 Ford,54 Chev. 60s English Ford/ MGB in England, have a 67 Saab now but never had a positive ground car. Lived in Port Sudan, Sudan for a year. Been to Vietnam, Thailand, lived on Guam 2 yrs. England for 5 yrs. still no positive ground. So if I have never had one or seen one doesnt mean they dont exist. Always wanted to go to Australia but if you're having plumbing problems? Not sure now.

Rich

[Datsun.David]

Awesome response Rich!

dw

[pebbles]

53 ford was 6v positive ground,,, last year for the flathead v8.

[mraitch]

My 49 MKVI Bentley was positive ground - cost my mechanic a new Pertronics because he forgot.

FWIW - from the Internet
I have long wondered why my 1937 MG has positive earth whilst my 1936 Bentley has negative earth. Many cars constructed before about 1950 were positive earth with later cars reverting to negative earth. The following is a Lucas reply to a similar question regarding positive and negative earth put in 1966.


“Electrical equipment will only function with current flow which requires a return path for the current that has passed through the component. Originally most vehicle manufacturers utilised either a special wire or the chassis for a return path. To distinguish between the two wiring systems, the type that used special wire return was designated ‘insulated return or I.R’. and the chassis return as ‘earth return or E.R’.

Earth return would be dangerous where high voltages are used, but earth return is quite safe for low voltages between 6 and 12 volts, but any leakage between wiring and chassis causes corrosion at the leaky point.

Pre-war insulating material was usually basically wood, rubber, ebonite, glass or later bakelite. All but glass had tendencies to exhibit minute leakage, which over a period of time encouraged corrosion of the terminals. Battery connections were most prone to corrosion because of the added effect of the acid. Earth return is only effective if the battery has one terminal connected to the chassis, and for certain chemical reasons less corrosion occurs if the positive earth terminal is earthed.

It was because of the advantages of earth return that by about 1935 nearly all manufacturers were using this system and to reduce corrosion the positive battery terminal was earthed. An additional advantage
of positive earth was that a sparking plug sparks better with the earth electrode positive.

Since the war, plastic insulation has been used extensively, and because of this the leakage current no longer prevails. As there is no leakage to bother about, it does not matter which battery terminal is earthed from a corrosion point of view. Sparking plugs still operate more effectively with a positive earth electrode but now that ignition coils can be made which reverse the earthing potential of the power flowing through them, it is possible to use a negative earth battery and still obtain positive earth high tension. In theory the last few facts are a little more complicated than stated but in practice the effects are still the same.

Post war negative earthing has many factors in its favour, and the most predominant are given below: -
Television interference is easier to suppress with negative earth, and of course this was no bother before the war. Electrical equipment is now being used as standard in more cars additional to the radio (probably
the first electronic devise used in a British car)

It is characteristic of all electrical apparatus, as opposed to electric, to be polarity conscious, that is affected by which supply terminal is earthed. If a transistor is connected the wrong way round it will be immediately irreparably damaged. Universal negative earthling would ensure
that all power supplies to electronic gear were to the same earth and therefore reversed connections impossible. Electrical components like bulbs etc are not affected by which terminal is earthed, therefore these can be unchanged and universal in their application.

To help avoid any confusion which may arise in the difficult in-between changeover period, when vehicles of both types of earthing are produced, components are being marked + and -. To consider an ignition coil, for instance with positive earth,+ is earth, so this is for distributor contacts and – is live, so this is the ignition feed. The same coil when used with negative earthing would be earth at – and so this is for the contact breaker, and live at +, making this the ignition feed.

Thus to summarise, Positive earth gives a better spark and less corrosion when insulators leak current. Negative earth interference is easier to suppress and electronic components are less likely damaged”.

Written By David Berry

[dbrick]

The roadster did originally come with a ground wire from starter bolt to frame.

Ross
sports imports

Makes sense that they would, but I don't recall any of the cars I've had having one. Maybe people left them off when replacing the starter?

I had a 53 Ford, 6v Pos ground so the Pos terminal of the 6v battery was grounded, as it was from the factory and all stock electrical system.
I don't remember if it came with it or if my friends and I dreamed it up, but believe it or not it had a 12 volt Neg ground radio in the dash with a 12 v battery in the trunk. A wire ran from the Pos terminal of the 12v battery to the radio only and the radio chassis and the neg terminal of the 12v battery were grounded. You had to charge the 12v battery every week or so, but it all worked just fine. I guess the current found whatever return path it needed?

I wish I had a photo, that was one UGLY car, a feeble and badly done attempt at a lead sled. I was desperate for a car to drive, swapped him my unfinished 41 Plymouth Gasser coupe for it. In retrospect, bad trade, but it got me around for a year.

[Nissanman]

Talking of radios, I wanted to fit one to my SP310 for completeness.
I remembered I had one in storage that I removed from my P510 years ago.
Your actual AM push button wireless
I also remembered that it had a polarising plug on the case to switch it from positive ground to negative ground and vice versa.
VOILA! problem solvered!
It isn't installed yet but it is the right size for the console cut out and will do just fine!
Probably will never listen to it though


1953 Ford Crestline Victoria

[sports imports]

The threaded hole in the top of the frame near the starter is where the factory location of the ground strap is attached.

Ross
sports imports