Negative or Positve ground ?

[Frank Howard]

They weighed too much.

Frank Howard

[Elan45]

The tach is the only polarity sensitive item you've listed. Radio would
be another. Switches and starter motors don't care which way they're
hooked up. Generators can be polorized to either condition (see the shop
manual) and coils must be connected properly for the polarity, but will
function fine in either polarity.

On Tony's brother's Elan, that he was able to get for a song, because
the battery was installed reversed, the only thing that would have
happened is the generator wouldn't have charged, because it was not
re-poloraized, the tach wouldn't have worked but the temp and oil
pressure are mechanical and don't care. The only thing that would have
been backwards was the ignition coil, and I've seen them hooked up in
reverse and the cars run for months unknowing. Starters do not run
backwards, they don't care. Probably more of a grounding problem and the
fact that Sears probably stuck in the biggest "die-hard" they could find
and it was rattling around behind the seat.

Roger

[Frank Howard]

Dave,

As the stock generator puts out 22 amps and it is difficult to find an
alternator that puts out less than 35 amps, I knew the smallest alternator available
would be more than sufficient and the small size could only help with weight
as well as accessability. Based on this, I went looking for an alternator out
of a 3 cylinder Geo assuming this was the smallest available. While
searching through the junk yard, I came across a 1988 Mazda 323 that had a recently
rebuilt alternator. It was so clean that I have never washed it and to this
day, it is the cleanest part on my car. It is made by Mitsubishi and has proven
to be a great improvement. Also, it came with a pulley that matches the ones
on the Elan so I didn't have to switch that part out. I did have to fabricate
a couple of brackets though.

Frank Howard
'71 S4 SE
Minnesota

[BenL]

Since at that point no one else had replied, I decided to succumb to
"Male Answer Syndrome" and reply.

As someone else said, the best way to get the correct answer on the
Internet is to post the wrong info.

---Ben

[Elan45]

Dave Bean used to have a page in their catalog with all sorts of
stickers, decals and plates. Pretty sure there was a "Negative Earth"
sticker included. Looked like the one that was original to my '68
Cortina GT, when new.

Roger

[frearther]

<How, when the starter is turning in reverse, does he get it to run? >

The newer (replacement) starters will run in the same direction no
matter what their polarity. I didn't quite believe it, so I tested
one on the bench. Damned if it doesn't go in the same direction
regardless of polarity. Could be that even the old Lucas guys did the same.

Art

[mikecauser]

Are you really sure you don't mean MGB? I recollect seeing such labels
on BMC cars in the late 1960s - early 1970s. Mainly red in colour I
think.


Mike

[mikecauser]

But hold on. In 1968 the British car industry did not use the concept
of "model year". Some new models were introduced at the big shows,
London in the autumn and Geneva in the spring being favourites, but if
you brought out a new car at a show you had to share press coverage with
the other makes, doing it between shows got you all the motoring columns
in all the papers. For the industry as a whole the switch to negative
earth was often made when a particular engine changed dynamo for
alternator, but IIRC it was spread over 5 or 6 years for everyone to get
on board.

In the case of the Elan, in Robinshaw & Ross, Appendix A, the change
point to negative earth is given at unit 7895, the first S4.


Mike

[lotuselan2]

Mike

I went back and checked my pictures. I had several pics of MGB's with the
hood open and no labels but they were mostly later ones like '74. Earlier
ones did not have label visible.



The MGA's in my pics had their hoods closed. But I am sure it was the A's
and the labels were black text on white background. Who knows if they are
original? Somebody in club could have been selling labels last year!


Ken

[lotuselan2]

How much does it weigh and cost?



Ken

[tvacc]

While I usually bow to Roger's expertise.he is far more knowledgeable than I
about most Lotus things, I can tell you that when I had my S2..I reversed
the polarity on the coil and the car ran like crap. I remember an old
mechanic telling me that if you have reverse polarity the spark jumps the
opposite way.and you get more corrosion.erosion on the electrode. I was not
there when my brother in law bought the car.It was about 4 years before I
met my wife. (It was because of Lotus that I did meet my wife.but that is
another story).



But from personal experience I can tell you that I experienced rough running
with a reversed coil.don't know if the explanation above is why.I can only
tell you it happened. My brother in law's car may have been because the
battery was not charging.they jumped it and then there was not enough juice
in the battery to run the car. I would vote for that.



Tony Vaccaro

[poiuyt]

they weighed too much!

steve b

[Garibaldi]

Hmm, I remember a friend reversing terminals on his sh*tbox MB 220 SE
and when he turned the key, the generator had turned into an electric
motor and incinerated its fan belt. Flashback or true? You decide.
GP

[Elan45]

Tony,

Thanks for the comlpiment. I would also agree with you that low battery
could have been a big part of the problem. I know cars ran better when
the coil was connected correctly, but I don't remember that fault ever
being a night and day kinda difference in the way a car ran. From 1970
thru 1974, I worked in the trade on mostly MG, Triumph and Healeys, so I
saw lots of problems with them and I'd like to think I put a smile on
lots of owners faces. The last couple of those years my time was split
from my trade to finishing my degree and I retired from the auto
business when I collected my diploma. But then I was able to enjoy my
own toys and my first Elan moved into my garage in Sept '74, so I've
been at it a fair while.

Roger

[denicholls2]

While Roger is correct that the tach is polarity sensitive (as is the
radio and the coil) and may be damaged by reverse current, this does not
mean these components must be swapped out to reverse polarity. The
polarity of their connections must merely be reversed.

Of course, this is made difficult by the practice of using the case to
carry the ground voltage to the unit and the need to isolate the case
from the metal components to which it is grounded. Happily, this is not
a major issue on a glassfiber car as it is on a steel one.

I'm still puzzling over the ability of a DC motor to behave like an AC
motor. I'll take your word for it, but it ain't the natural behavior.
They must have felt that the extra cost of current-sensing logic in the
starter was worth being able to use the same starter regardless of
polarity.

The heater fan motor may be an AC unit or current-sensing as well. But
if you have electric radiator fans, they are usually DC and must have
the connections reversed to run in the right direction. This is a
common fault with the Europa cooling fans, some of which are reputed to
have come from the factory fighting the natural airflow.

-- Doug Nicholls, 54/1822 Ma~