Ballast resistor, Elan Sprint

[John Larkin]

I cannot find a ballast resistor on the low tension feed to the coil in the Lotus wiring diagram. Is there supposed to be one?

Anybody got a wiring diagram showing it?

John Larkin

[john.p.clegg]

John
Have you got a 6v or 12v coil? You should be able to tell by numbers on the base of the coil if it's a 12v coil you might not have one....

John

[Frank Howard]

John,

Whether or not you have a ballast resistor depends on the coil. Some coils run on 12V and others run on 9V (could be 6V, not sure). The 9V coils say on the outside "For use with external ballast resistor only". The PO could have replaced the original 9V coil with a 12V coil and tossed the ballast resistor.

The ballast resistor should be right beside the coil, between the white iginition wire and the positive side of the coil. Hope this helps.

Frank Howard
'71 S4 SE
Minnesota

[John Larkin]

I thought that the ballast resistor was wired into the loom (as in a Rover that I own), and I was mystified why I could not find it in the wiring diagram. I discarded the original coil from the Sprint when I got the car about three months ago, and cannot remember if there was an external ballast resistor fitted.

I have now fitted electronic ignition which stipulated that a non-ballast low tension feed was essential for the dry coil that came with it, and I was worried that I had a covert ballast resistor waiting to do damage!

Thanks for the information.

John Larkin.

[Frank Howard]

John,

My 1974 Europa Special came with a ballast resistor that looked like an American quarter. That's right, it was a small disc with a tab on each side. One tab was connected to the ignition wire and the other was screwed directly to the positive side of the coil. I know it came from the factory that way because the Europa manual shows a drawing of this style of resistor.

Because you have a Sprint and Sprints were built around the same time period, I thought it might be possible that you have this style of ballast resistor on your car. Do you?

On another note, American GM cars use a special resistive wire rather than a ballast resistor. It's easy to replace this wire with standard wire and not realize that you have lost your ballast resistor. It appears that your Rover is wired this way.

Frank Howard
'71 Elan S4 SE
'74 Europa Special

[john.p.clegg]

John
You could always get a meter on the supply lead and check out the volage with ignition on and start-see if there's a difference....

John

[freddy22112211]

The original ballast resistor looks like a bit of wire! (Perhaps a little thicker)
Gordon

[types26/36]

The original ballast resistor looks like a bit of wire! (Perhaps a little thicker)
Gordon

Never seen one as you describe on a Lotus although I do remember some Fords had a "fuseable wire link"
I've only seen the type pictured below on Lotus.
There is a bit about them on elan.net:
http://www.lotuselan.net/publish/lsb_co ... coil.shtml