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Battery cables backwards what now

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M

mightymidget

Jedi Knight
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When I looked under the hood of my new 65 MG Midget I found the battery was cabled pos.2pos. and neg2neg. I was assuming it should be postive ground car. So if it is a postive ground car what damage has been done,

It has been hooked up that way for years. I have notice alot of wires pulled from under dash. Also if it has been changed over to the american way how can you tell?
 
I can't say if it' a + ground car or not and I don't know when they went to the "regular" way( I know nothing about eletrical on a '65), but I have accidently hook up batties backwards. If caught quickly, no harm done.

If you didn't get lots of sparks, smells, noises or smoke, I wouldn't worry too much right now.

I inherited my grandmother's (actually my mom's) '68 bug and my uncle or father put new cables on it at one point in time, but + was black and - was red. Needless to say I found out REALLY quick that someone wasn't right when I hooked up my nice, hot battery.

I guess they were on sale at the time and color didn't matter. THANKS UNK !!!


Note: I haven't hooked up one of these back'ards.
 
The car really won't care about polairity it has been running assuming that everything was converted over - generator polarized etc.

But running positive earth won't impact longevity of anything.

Does it run like that / have you seen it run with the current grounding?
 
Tach would be messed up. Fuel gauge might be. Generator must have been repolarized or it wouldn't have run long. Negative ground isn't "american way" I don't think, it's just what was eventually standardized to, maybe here earlier then England. I converted mine to negative ground last winter just to make life easier with stereo and pointless ignition, the emergency jump start, any other "add on's" down the road. Switching the tach over is the only 'hard part' and even that wasn't a big deal. I don't think anything is polarity sensitive other than the tach, the heater motor doesn't seem to care. I was convinced the heater wasn't blowing as hard after the conversion so I switched it's leads around but can't tell a lick of difference.
 
Just purchased the car that has been sitting for a couple of year. and ready to charge battery and go through a crank up and start process.

just didn't know if previous owner may have damaged regulator/generator/starting system if battery was installed backwards
 
I'm not sure when the switch to negative ground took place, but a quick check of the wiring diagrams in my Haynes manual doesn't show negative ground until the Mark III Midget/Mark IV Sprite. In any case, if you car is running negative ground, presumably it's been converted. If the car has been run that way, it's obviously OK. So, it's water over the dam at this point. Sounds like your concern is that it never was converted but that maybe some lemuel hooked it up negative ground and left it that way.

As for negative-ground conversions--the regulator, generator, starter and so on won't be affected. Yes, it's best to repolarize the generator when you switch from positive to negative ground, but it's likely that you won't notice it if you don't. The current leaking into the field coils from the ignition idiot light will probably be enough to get the generator started right, and once it's running with the proper output polarity, it will magnetize itself in that polarity. Just to be safe, you might want to do the polarization. It's easy.

An electronic tachometer won't work if it were set up for positive ground, but there's an even chance you wouldn't have blown anything. The fuel gauge should be OK. I'm not sure about the wiper motor--if it has a field coil, it won't matter; if it doesn't, it will run backward but that might not matter. It's a good idea to reverse the coil primary leads when converting, which might or might not have been done, but the car probably will run OK even if this is neglected.

Thre's probably something else I haven't thought of--but all in all I don't think you have much to worry about.
 
Well I just found out it is not a 1965 but a 1967, I will research the date they change from positive ground
 
Changed in '68. It would be a negative earth car from England, but who knows what's actually been done since then... If it has a generator and OE stuff, not much other than the tach would care. I'd be for hookin' it up positive earth and seein' if the tach registers anything realistic. Then convert it later to negative earth to be able to live with it in the 21st century.
 
Why change it at all?
Unless you want a stereo or an alternator.
Leave it alone.

My Fords are ALL positive ground, and one thing about positive grounding, external battery corrosion in minimized.
Heck, I learned that back in the early 60's.

In 40 years, I think I've cleaned my cables three times on the flatmotors.
On negative ground, we change the cables every 3-4 years.
 
I am going to step into something that I will regret but I think that Drew is right that it is not a '65 but I am beginning to believe that it is a '73 or so (split bumpers).
With a common ruler, what diameter is the face of the speedo /tach? Or more easily, show us a picture of the dash.
Bill
 
Billm said:
I am going to step into something that I will regret but I think that Drew is right that it is not a '65 but I am beginning to believe that it is a '73 or so (split bumpers).
With a common ruler, what diameter is the face of the speedo /tach? Or more easily, show us a picture of the dash.
Bill
Click to expand...



not areal good photo
 
That dash shot puts the car at '68 or later. Can't remember when the round arch cars came in ('72?) -- that would be the upper limit. Forgot to look it up last night. Split bumpers would make it '70 - '72 I think. More knowledgable folks than me will chime in, I'm sure.

A good find, no matter the year.
 
You need to establish exactly what year the car is to start and then we can determine if it was originally a positive ground car and if so what to check for to see if it was converted to negative ground by a previous owner. Give us the first 4 didgets of the serial number located on the cowl behind the windshield and we can at least tell you what series it was to start with. If it's a GAN 4 or GAN 5 then it was most definitely a negative ground car from the factory.
 
I couldn't tell you what year it was if you ran over me with it. What makes me nervous is the fact it's not what was originally stated, nor does it appear to be what's on the title from what y'all are saying.

The dealer in me sends up a red flag when year of origin is undeterminable.
My concern at the moment is a swapped vin and "incorrect" title.
 
There should be a VIN plate riveted to the cowl just between the dash and the windshield, that's the number you need to determine what year it is.
 

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mightymidget said:
Billm said:
I am going to step into something that I will regret but I think that Drew is right that it is not a '65 but I am beginning to believe that it is a '73 or so (split bumpers).
With a common ruler, what diameter is the face of the speedo /tach? Or more easily, show us a picture of the dash.
Bill
Click to expand...



not areal good photo
Click to expand...

Banjo steering wheel and padded dash - 68 or 69.
 
Chassis sounds like a '65 then. Isn't the one on the frame the "important one"? Engine number doesn't matter, be interesting to see what the dash plate says I guess. Could easily be compilation of years at this point, many are.
 
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