Lotus Elan

Electronic Speedo

PostPost by: bcmc33 » Sat Sep 25, 2010 10:36 pm

Maybe an oddball question - but has anyone out there successfully fitted an electronic speedo to replace the standard mechanical speedo?
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PostPost by: elanman999 » Sun Sep 26, 2010 12:45 pm

Brian,
Yes I have an electronic one from Green Gauges dotcom. It works OK but it does spike every now and then. I also found the clearance between the sensor and the bolt head quite critical as if set incorrectly it did not work in the rain. Sounds silly I know but there we are. It is triggered from the rear disc mounting bolts. I think it would be better if it was triggered from something that gave a faster pulse rate but I have not come up with anything thats easy to do.
PM me if you need any more details.
Cheers
John
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PostPost by: TomR » Sun Sep 26, 2010 2:33 pm

I have a Smiths Cobra series gauge to allow easy calibration to the T5 transmission sender. Looks very similar to original (except the 180mph top end suitable for an Elan with 1000 hp). Got it at APT instruments in the US.

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PostPost by: bcmc33 » Sun Sep 26, 2010 2:34 pm

elanman999 wrote:Brian,
Yes I have an electronic one from Green Gauges dotcom. It works OK but it does spike every now and then. I also found the clearance between the sensor and the bolt head quite critical as if set incorrectly it did not work in the rain. Sounds silly I know but there we are. It is triggered from the rear disc mounting bolts. I think it would be better if it was triggered from something that gave a faster pulse rate but I have not come up with anything thats easy to do.
PM me if you need any more details.
Cheers
John

Thanks for the reply and info, John,

GreenGauges.com is the same company as Speedy Cables who I'd planned to call tomorrow.
It occurred to me that sensing could be done from the propshaft or diff flange, but as I have vented front discs, perhaps the easiest way for me to get an adequate pulse rate would be to sense off the vent vanes that can be seen from the disc O/D.

Please PM me some details and pictures of the speedo and sensor that you used, plus some information on how the system is callibrated.
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PostPost by: gjz30075 » Sun Jul 20, 2014 12:41 pm

Bringing up an old thread here, but I , too, would like some more details and pics of an electronic conversion. Brian, TomR, elanman99, anyone?

Thanks,
Greg Z
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PostPost by: elansprint » Sun Jul 20, 2014 1:15 pm

Used a laser cut toothed wheel with 36 teeth which we turned a male/female spigot in to fit in the prop shaft
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PostPost by: gjz30075 » Sun Jul 20, 2014 3:20 pm

Ian, can you elaborate? Where exactly on the prop shaft did you put it? I'm envisioning it between the propshaft flange and pinion flange.

What device do you have to 'shoot' at the toothed wheel? What guts do you have for the speedo, or did you buy a purpose built speedo for the conversion?

Thanks,

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PostPost by: elansprint » Sun Jul 20, 2014 3:33 pm

Greg we fit 4 speed auto box into Stags so we laser cut an 8mm thick 36 tooth wheel then turn a male and female spigot to fit inbetween the prop and gearbox flange or prop and diff flange latter may be easier on the ?lan. To keep the cars original speedo we have some electronics which picks up pulses from this wheel with a proximity switch eg crank sensor this operates the original speedo with a geared motor attached to the back but if you use an electronic speedo it should pick up from this wheel using the sensor supplied
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PostPost by: elanman999 » Sun Jul 20, 2014 4:18 pm

Greg,
Here is a pic of the sensor on my electronic speedo. As stated above it's using the disc mounting bolts to trigger on.
Cheers
John
IMG_0584rs.JPG and
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PostPost by: TroonSprint » Sun Jul 20, 2014 7:13 pm

I haven't fitted an electronic speedo to an Elan, but I fitted one on a Midget. It was a Speedy Cables instrument and they also supplied the Hall sensor. This looked like a small pencil. I mounted it on the diff case so that it could pick up the rotation of the four prop shaft bolts. It needed to be very close to the bolts for an accurate signal, and then it worked brilliantly. I would have thought the disc brake bolts were too few in number (only three) and rotating too slowly for the best signal. The prop shaft rotates nearly four times quicker than the wheels.

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