Negative Earth Conversion

The conversion is simple enough, appreciate feedback from those who have done this, specifically areas of concern or problem and anything to be specifically wary of

Malc

Be wary of youyourself or someone else subsequently connecting the battery the old way.

I appreciate the original post didn't pose this question, but I am wondering what is the point of converting to negative ground? Specifically, what problem does it solve?

Stephen Hill
Victoria, BC

Easier to run LED lighting if you want to.

there are other ways around that nowadays and LED headlights are not the best IMHO

I converted mine for the ability to use standard LEDs in blinkers. Only down side is that the red wires are now all negative.

"Negative Earth Conversion" sounds like a religious cult to me.
Are they alt right or alt left? Or is it determined by which side the shifter is on.
Ride On
Dave

The only advantage I can think of is the ability to use aftermarket electronics that are designed to use a chassis ground for the negative side of the circuits. The usual alternative for using such devices in a positive ground vehicle is to isolate the chassis of the device from the vehicle chassis, and then connect the vehicle chassis to the hot (positive) side of the device, and the vehicle hot lead (negative) to the chassis of the device. A bit of a pita, but it works. Not as big an issue as it used to be for car conversions back in the '50s and '60s, because a lot of the electronics now is fully encapsulated in plastic, and does not use a chassis ground as part of the circuit. I converted my landspeed Norton to negative ground for convenience in wiring the data logging, instrumentation, and nitrous systems. I could have done it with a positive ground configuration, but it was simpler this way.

Ken

Are you updating your charging system?

I'm not proposing to upgrade lighting or charging circuit at this stage.
Converting to Negative earth is just something I have done to several classic restorations as I just prefer it that way...
It also enables me not having to remember as all my bike old & new are the same
There are electronic reason for converting so I'm told... corrosion being the main one electrons flowing faster one way than the other apparently, but I'm not doing it for this reason,
There are all the obvious pitfalls... like the wiring then being the wrong colour, sparks jumping the wrong way on plugs if coil wiring not swapped.

I was really asking for views & opinions from the wealth of knowledge & experience here for any problems encountered with the process

Thanks

Malc

olympus said:

There are electronic reason for converting so I'm told...

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It doesn't really apply to these old bikes (I mean cherished classics).

olympus said:

corrosion being the main one

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As it's a 'wire return' system there's nothing to be gained, either way.

olympus said:

electrons flowing faster one way than the other apparently,

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:shock: :wink:

I'm a little rusty on some of this, but I think you will experience some real problems with the zener diode and the rectifier if they are wired negative ground. I don't think you can change the polarity without changing this aspect of your system.

Russ

rvich said:

I'm a little rusty on some of this, but I think you will experience some real problems with the zener diode and the rectifier if they are wired negative ground. I don't think you can change the polarity without changing this aspect of your system.

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Yes, the original Zener and rectifier are positive earth so would have to be replaced (probably with a reg/rec unit) however, from what he said, it seems Malc has done this conversion before.

Indeed On Triumphs T140 & T160 ....both Zeno & rectifier must be replaced or there will be smoking & the last time I cocked up the wiring the rectifier exploded

I've done this conversion by rewiring the whole bike from scratch.
IMO it's a piece of cake, and I'm no electrician.
I bought a cheap and cheerful regulator/rectifier (R/R), and I keep the charging system on a separate circuit with its own fuse - the R/R goes straight to the battery.
The bike came with Boyer electronic ignition, and it is a simple job to connect it up for -ve earth.
I have a total of eight fuses to protect the various circuits, so that I can tell where the problem is, unlike the single "something's gone wrong" OEM fuse setup.
Head lamps and horn are driven directly from the battery for minimal voltage loss (with fuses, of course).
I can buy inexpensive LED lamps, as +ve earth LEDs are expensive and difficult to find.
Fuses are blade ATM type, and easily bought at any car accessory shop or garage.
I dislike bullet connectors, and I found some cheap mains latch type connectors that work very well (see pics).
For in-line connectors I prefer to use the modern waterproof variety - bulky, but reliable.
Battery is by Motobatt - I like the four terminals and leak-free construction.



















As I dislike the original Lucas switchgear, I used some early Hinckley Triumph units, which work really well:

Having done several complete rewiring from scratch bikes, I can appreciate your nice work. And I'm still vacillating between rewiring to a plus or minus ground, because negative ground is what I'm by far most used to. I'm not an electrician either, but the gauge of the wires to the battery terminals jumped out to me as looking rather small.

That's a a very professional wiring job sir..
It takes a lot of trouble to go about a wire by wire replacement
What is the air filter you have fitted

Malc

Very nice piece of work and choice of components. I particularly like the wire anti abrasion covering. It looks super and I am sure does a good job.

pantah_good said:

the gauge of the wires to the battery terminals jumped out to me as looking rather small.

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The front wires are from the regulator/rectifier, and are thin wall construction and compatible with the existing R/R wires - should be sufficient.
The rear wires feed the fuse boxes and ignition switch, and are of a higher grade (3.00mm²/13AWG).

olympus said:

What is the air filter you have fitted?

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It's a K&N 0990 https://www.knfilters.co.uk/search/product.aspx?prod=R-0990