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Bugeye Negative Ground

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Paul McGuffin

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I’ve had my Bugeye now for almost two years. I just found out this evening my car is negative ground. What gives? Is it that easy to convert? I have a generator still.
PM
 
Yes Paul, it is. There isn't anything (except possibly a radio) that is polarity sensitive. All that is needed after switching the cables, is to polarize the generator. That can be done in a few seconds by sparking the appropriate wire from the generator to a battery terminal. It can be reversed back in the same way.
 
Gerard said:
Yes Paul, it is. There isn't anything (except possibly a radio) that is polarity sensitive. All that is needed after switching the cables, is to polarize the generator. That can be done in a few seconds by sparking the appropriate wire from the generator to a battery terminal. It can be reversed back in the same way.
Click to expand...

So, you don’t have to change the voltage regulator in any way? And, I would guess, if I get an electrical tach, it needs to be Negative Gound?
 
Paul McGuffin said:
So, you don’t have to change the voltage regulator in any way? And, I would guess, if I get an electrical tach, it needs to be Negative Gound?
Click to expand...

There are pictures and diagrams of what has to be changed in a tach to switch polarity, but the change made by users 99.999% of the time is from positive to negative ground. There is no rational reason to change it back to positive. If you get an electric tach,, it WILL BE negative already.
 
I agree with Bill. If the car is already negative ground the only reason to change it back is for "originality".

In addition to changing the battery connections and repolarizing the generator, you also should swap the low tension wires on the coil. The coil will work wired either way but when wired correctly for the ground it will produce a bit more voltage and a hotter spark. Also make sure a previous owner didn't fit an electric fuel pump (or other accessories) as they can be polarity sensitive.
 
Well yes, usually. Bugeye's never came with electric tachs, so had not thought about that. If you have a period British one, they are typically positive or negative ground and are labeled as such as I recall. There are aftermarket ones I've seen that have a polarity switch.

Paul McGuffin said:
So, you don’t have to change the voltage regulator in any way? And, I would guess, if I get an electrical tach, it needs to be Negative Gound?
Click to expand...
 
I have no intent on going back to Positive Ground.
 
Still there for now but will be changing to an Alternator and adding Speedhut Gauges for GPS Speedo and Tach.
 
I received the instructions below from AH Spares three days ago for repolarizing the generator to work with negative earth:

"To polarize a Lucas dynamo for NEGATIVE earth

Your battery's NEGATIVE terminal should be connected to the chassis or frame.
Disconnect the D & F wires from the dynamo. Run a wire from the unearthed terminal on the battery (i.e. positive) and "flash" it onto the F terminal on the dynamo. By flash I mean brush it over the F terminal 2 or 3 times until a small blue spark can be seen.
Your dynamo's field is now polarised for negative earth and ready to safely connect to an electronic regulator"
 
Just got a further clarification from AH Spares:
"When you do the conversion to negative earth the process can damage the voltage regulator that is fitted. You will not know this until you have done the conversion as this will only become apparent when there is no charging voltage as indicated by the ignition light staying illuminated.
The new voltage regulators are solid state internally now.
Yes you will need to ‘swap’ the low tension wires around on your ignition coil."

If you're already negative ground, stay that way! Doug
 
I've got a pile of RB 106 regulators that are probably good but I have no way of testing them. No need for any new ones either so for now they will set. Most likely never need them since I only envision changes to an alternator in the future.

Kurt.
 
Just got wondering: can anyone advise if the 'flashing' could be done by isolating the generator/battery, such that the voltage regulator would not be put at risk? Thanks, Doug
 
twas_brillig said:
Just got wondering: can anyone advise if the 'flashing' could be done by isolating the generator/battery, such that the voltage regulator would not be put at risk? Thanks, Doug
Click to expand...

Sure, all that is needed is to get a bit of residual magnetism in the generator. In fact in most cases the generator will polarize itself. Remember all that is needed is a brush across the terminal. Not sure you would want full 12V max amp though. I think I would just try it and see if it actually needs to be polarized. Give it a little time.
Kurt.
 
Ok, and consider this. After I changed my Bugeye to negative ground to accommodate an electric tach I put one of those stickers on the firewall which says IMPORTANT THIS CAR IS WIRED NEGATIVE EARTH. It is a good thing for anyone working on the car who would know enough about Bugeyes to assume it was still wired as original to be informed of this.

I have some personal experience with this. Around 1982 I had my '67 Midget and girlfriend out for a Sunday drive. When we started for home after a short picnic break all I got was a click when I tried to start the car. I asked a guy nearby to give me a jump, and as soon as I touched the cables from his car to my Midget's battery terminals the insulation on the battery cables started smoking and melting off the copper wire in long strands that sort of looked like melted mozzarella cheese coming off a freshly baked pizza. My hands were burned quite badly trying to get the cables off.

Well, of course you know by now that Midget was still positive ground, but at the time, I didn't even know what that was. I just hooked up the cable going to his chassis ground to the ground going to my chassis, and so on. Logical, right? Ummm. Yes, but. I'd wired the batteries in series, not parallel. 24 volts vs 12 volts. I was a kid, what did I know.

Somehow I did not burn up any electrics and all that was destroyed was the battery cables and the skin on my hands. The real problem wasn't the starter or charging system at all. It was a blown throwout bearing. I speed shifted that car all the way back to town, about 17 miles, and luckily hit every traffic light all the way. But, I will say that was a long day.

Anyway, that's a long way of explaining why I put that negative ground sticker on the Bugeye's firewall.
 
Be careful of fuel pumps, radio's, and electronic tachs when making the switch. I recently fried one of the newer Facet pumps because I forgot I was fitting it to a car that was still pos ground...got one click out of it.

Kurt.
 
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