Lotus Elan and Lotus Elan Plus 2 Forums

Posted: **Fri Oct 15, 2004 2:04 pm**

I recently purchased a '70 Elan S4 that has a non-working tach and a
Lumenition Optronic electronic ignition that was installed about 10 years
ago. The tach lead is currently disconnected from the side of the coil
because ever since the new electronic ignition was installed, the car will
break down if the tach lead is connected. Has anyone experienced this
before? Ideas for how to overcome? Thanks. Dan

Also, the speedometer bounces around wildly. What needs to be replaced?
Thanks again.

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Posted: **Fri Oct 15, 2004 2:46 pm**

On Lotus Elan.net there is a tech article about tachos and electronic
ignition. I have an Optronic and used to have bouncing tacho, but since
installing a "ring-main earth" it only bounces when I go over a hump-back
bridge!

The bouncing speedo is a whole other thing!

Pete
----- Original Message -----
From: "Dan Collins" <***@***.***>

Sent: Friday, October 15, 2004 3:03 PM
Subject: [LotusElan.net] Tach and Ignition not getting along

Posted: **Fri Oct 15, 2004 3:31 pm**

What's a ring-main earth?

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Posted: **Fri Oct 15, 2004 4:22 pm**

Ring-main earth? A ring-shaped electical fitting, for use on a bolt or stud
which is a primary Earth (ground) connection.

Bouncing speedo is most likely a worn speedo cable. But could be the angle
drive on transmission or the speedo itself. Try a new cable first; easiest
and cheapest.

Rich Boyd

At 08:30 AM 10/15/2004, you wrote:

Posted: **Fri Oct 15, 2004 4:48 pm**

This is a very common problem with any cable driven speedo. Very often the problem is that the speedo cable's lube has dried out. Since the cable is essentially a very long spring, twisting it when there is extra friction tends to wind it up and at a certain point it unwinds to catch up. Ergo, an erratic imput to the speedo head. I have had good success by unscrewing the cable from the speedo and dribbling a penetrating oil such as Aero Kroil into the cable housing. It will slowly seep in, repeat this several times. It might be useful to drive the car a bit with the cable disconnected to work it in, then add more. Also, this gives your passenger a chance to ovserve the rotation of the cable, looking for irregular rotation. Finish up with a light machine oil such as 3-in-one to ensure that it has lubrication.

The angle box either works or doesn't, not likely to cause bounce.

Worst case, the speedo itself. Very likely the dried lube problem again Sleeved bushing such as this are very porne to "gumming up" due to dried lube. Cleaning and re-lubing is very often all that is required.

Cheers!

Stan

Bouncing speedo is most likely a worn speedo cable. But could be the angle
drive on transmission or the speedo itself. Try a new cable first; easiest
and cheapest.

Rich Boyd

Posted: **Fri Oct 15, 2004 9:42 pm**

Perhaps not the correct technical term, but instead of relying upon the
chassis (frame) to provide the earth (ground), I have run a cable directly
from the battery -ve terminal to the earth points around the car; and guess
what? I've still got an earthing fault somewhere, don't you love Joe Lucas?

New loom coming soon.

Pete

Posted: **Fri Oct 15, 2004 9:58 pm**

Having just read my previous post maybe I had better explain to non-UK listers what a ring main is! In the UK domestic electrical supply is single phase 240 volts, you get live neutral and earth (unless you live out in the sticks where you provide your own earth). The 3 cables go to a distribution fuse board and typically you will have a ring main downstairs and another upstairs. From the fuse a three core cable goes to the first socket outlet, on to the second and so on until it returns back to the fuse board, thus completing the "ring".
I have run an earth ring around my car in a similar fashion.

Pete
----- Original Message -----
From: elansprint71
To: ***@***.***
Sent: Friday, October 15, 2004 10:43 PM
Subject: Re: [LotusElan.net] Tach and Ignition not getting along

Perhaps not the correct technical term, but instead of relying upon the
chassis (frame) to provide the earth (ground), I have run a cable directly
from the battery -ve terminal to the earth points around the car; and guess
what? I've still got an earthing fault somewhere, don't you love Joe Lucas?

New loom coming soon.

Pete

Posted: **Sat Oct 16, 2004 4:11 am**

Wow, no wonder the empire folded, did lucas design house wiring too?

elansprint71 wrote: