Lotus Elan

Converting an S3 to Negative Earth

PostPost by: SeanB » Tue Jun 04, 2019 4:28 pm

Hi Guys,

I was wondering if there was a definitive guide on converting an S3 to negative earth. I want to switch to an alternator at the same time.

I've read quite a bit on here and it seems that once you have ditched the dynamo and gone to an alternator and had the tacho converted, there isn't much else to it????

What about the starter motor etc?

All advice greatly received.

Thanks.

Sean..
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PostPost by: ericbushby » Tue Jun 04, 2019 5:19 pm

Hi Sean,
The starter motor is OK, being a series wound type it is not polarity sensitive.
The coil connections should be changed over. Although it will work both ways, it is more efficient when connected correctly.
It will probably be marked Pos and Neg, or + and -.
Eric in Burnley
1967 S3SE DHC
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PostPost by: SeanB » Tue Jun 04, 2019 6:04 pm

Thanks Eric,

What are my options for getting the tacho modified?
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PostPost by: ericbushby » Tue Jun 04, 2019 7:10 pm

Hi Sean,
You can probably do it yourself.
Search for --positive to negative ground conversion lotus cortina-- and there is a description with pictures
explaining how to do it.
However there is a mistake in the write up. The component described as a diode is very obviously a 150 ohm resistor but everything else is OK.
While you are in there it is a good idea to change the ageing capacitors especially the 100 mf electrolytic which should not have lasted this long.
Best of luck
Eric
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PostPost by: Elan45 » Wed Jun 05, 2019 4:01 am

And the window up-down switches will operate backwards. I converted my SS a couple of years back and so far, I'm just pushing the switch up when I want the windows to go down. Most of my time in the garage has been working on the Coupe restoration. I've not been ready to pull out the dash to reverse the wires on the back of the swiitches.

Roger
'67 Elan S3 SS DHC
'67 Elan FHC pre-airflow
'67 Elan S3 SE upgrade to 26R by Original owner
'58 Eleven S2 (ex-works)
'62 20/22 FJ (ex-Yamura)
'70 Elan +2S RHD
'61 20 FJ project
'76 Modus M1 F3
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PostPost by: gjz30075 » Wed Jun 05, 2019 8:51 am

Roger, et.al, I was able to simply rotate the switch, leaving the dash in place. You have to pull the plastic
underdash valance, of course. Access is good. I removed the switch, wires intact, and rotated the
switch, then re-inserted the switch in the dash.
Greg Z
45/0243K Sprint
36/5727 pre airflow coupe
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PostPost by: Craven » Wed Jun 05, 2019 10:27 am

May be simpler to remove door card and reverse motor connections or the connectors at the door check.
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PostPost by: Elan45 » Wed Jun 05, 2019 2:33 pm

Greg,

Perhaps I can rotate the switch, but this is the Super Safety, so rocker switches. I did make a special short, small diam screwdriver a few years ago to remove the window switch, so I could take it apart and clean the internal contacts, so that the window could operate. Still a royal PITA. I seem to remember the connectors by the door check are polaraized, so unless I want to splice in new connectors and I don't. I'll check this next time I visit the car in 6 months. I also have the small alternator, but have not fitted it yet. Got to make the mounting adapter. I did bring the alternator back north this year, so that when I build the engine for the coupe restoration, I can use it as a trial fitting station so that I know it's line up. Besides, all my fabrication stuff is in Ohio.

Roger
'67 Elan S3 SS DHC
'67 Elan FHC pre-airflow
'67 Elan S3 SE upgrade to 26R by Original owner
'58 Eleven S2 (ex-works)
'62 20/22 FJ (ex-Yamura)
'70 Elan +2S RHD
'61 20 FJ project
'76 Modus M1 F3
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