Lotus Elan and Lotus Elan Plus 2 Forums

Oh - the tach. works now!
After varing modes of the orig. tach. from intermittent, grossly incorrect readings, to not functioning at all; I purchased the Spiyda Design circuit board replacement, works a treat. ( no connection etc, just a satisfied customer)
I changed the car over to Neg. ground, which I was doing anyway as safer (for me) to have all cars the same to avoid confusion. (Still running the generator and orig. style regulator on the Elan.)

Jack

Your car originally was a "positive earth" and you made it a "negative earth" ?

Yes, the S2's were originally positive earth or ground, the tachometer Spiyda replacement circuit board kit I mentioned requires a neg. ground. The only thing you have to change aside from the tach. is striking the generator to reverse polarity as per the Elan manual, I may have swapped the leads on the fuel gauge but I don't recall as had that out briefly anyway. I am not an electrical wizard just checked things proir, starter is shunt wound so not polarity sensitive.
The 7 is neg. ground as are the daily drivers of course.
Jack

I'll bet you changed the battery post connections as well!

I have a Spiyda unit as well and haven't gotten around to fitting it. Seems like I thought the calibration for a computer illiterate like me might be a hurdle.

I've enough other projects right now.

Kurt.

Hello
mine was probably positive earth (fhc 1965) but when I bought it, it was negative earth.
I wanted to make it "positive earth" as genuine, but some friends don't recommend it.
What do you think of ?


Now , my Elan is "negative earth". The generator has been replaced by an alternator, the starter seems to turn in the right direction and the tachometer doesn't work.
For lamps: no change.
For spark : anything changes ?

I don't think they make "Positive Earth" Alternators.

I agree with you

my car was equiped with additionnal front lights, return lights and 3 oil temperature indicators (motor, gearbox and final drive). That's perhaps the reason why the alternator replaced the generator

Nono,
The ignition coil also needs to be reversed because although it will work both ways, it is more efficient one way. The are often marked + and --. The negative side will go to the distributor and then to earth on a negative earth car.
If you have the early RV1 tacho then the wiring inside will need reversing. It is easy to do when you get in, just two connection to change over.
Have a look at this description, but when it mentions a striped diode, it is really a resistor.
http://www.lotus-cortina.com/electric/convert.htm
It took me nearly a week to get the glass out, soaking it in release oil and gently prying, and then 10 minutes to change the wiring inside.
It is worth changing the ageing capacitors while you are there.
Best of luck
Eric in Burnley
1967 S3SE DHC

Thanks a lot!
mine is a RVI

I probably will have a look at this this week-end, but it will take me a long time to understand all !!

nono,from everything I've heard about the Spiyda unit I would consider fitting that if you tear into the RVI. Having said that I have converted a couple of RVI's and its not difficult. When you are done though it will still behave like an RVI!

Kurt.

is there any view or topic on Spiyda ?

is it this one ?
https://www.spiyda.com/magento/index.php/smiths-rvi-rvc-conversion-board.html

I'm not sure, but if you have been running your existing tacho after reversing your battery & before rewiring the tacho, you might have destroyed the electronics.

So that's another good reason for buying the Spiyda kit.

https://www.spiyda.com/magento/index.ph ... board.html

when I get it, the car was "negative earh"
I don't know if it was genuine, but I don't think so; mine is born end 1965

and I never saw the tacho working. Perhaps already destroyed because of reversing ???

nono,
If you hunt around the site you will find video's showing the change, also the calibration files. The kit includes a plug and alligator clips to use your iphone or similar device to input the calib. signal, real easy to do. When calibrating (which you can do on the bench) power it from a car battery though, not via a battery charger as the charger will input a 60hz (50hz uk?) hum on top of the calib. signal (so I found out )
I swapped the coil leads of course for neg. ground. Also I had to run an extra wire from the distributor side of the coil to the signal input to the tach. as the early Elans (rvi tach's) don't have this wire.
Jack