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Electronic Speedo (Not Swimwear)


spitfire6

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Hi,

Anybody know of a deal/thingy that I can retrofit to my original Triumph speedo obtain a modern electronic waveform?

I believe the waveform should be OBDII??

 

If anybody knows what the OBDii standard is for the speedo, I guess I could, replicate this from the prop-shaft with a sensor and trigger device?

Bottom line is, I guess.

What frequency or pulses per mile do I need?

Cheers,

Iain.

 

PS. Spitfire is really off for MOT in the morning and then I can pick it up next week.

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AFAIK most modern stuff uses various forms of proximity sensors - usually either VR or Hall effect. These sensors are usually specifically packaged to suit the particular manufacturers wants and pulses per mile/wheel rev or whatever will also be set by the vehicle maker so suit their electronics.

 

I'm quite sure that by the time the speed/distance data reaches any OBD readable form it will already have been processed by on board electronics.

 

What are you trying to do? Many aftermarket ECUs will read pulsed speed signals direct from VR or Hall sensors for traction control, mpg, speed sensitive PAS or whatever.

 

If you just want an electronic speedo, many solutions are possible. Richfield, Caerbont and Speedy Cables all do electronic speedos (and some will even convert existing ones). I've also read online accounts of people modifying electronic tachos to work as speedos.

 

Cheers

 

Nick

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GPS receivers can be set to read MPH, and are allegedly more accurate than any speedometer working off the transmission, which by Statute must always overread. No idea if GPS is legal though, and it would need a minute or so to aquire enough satellites.

John

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I don't think there is a standard OBD(on board diagnostic) speed sensor wave form. Some produce sine waves and some produce square waves and at different reference voltage. VDO makes an electronic speedo that is adjustable and can be driven by different types of speed sensors. here is a page where some one investigated the different signals involved with a Volvo electronic speedo. I think this Volvo gauge could be installed in a Smiths housing if you were very motivated.

http://cleanflametrap.com/speedo.html

Edited by motov8id
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Everybody,

 

Thanks for the link Esxefi. A lot of interesting stuff and I read that a standard of sorts is 1000 pulses per mile, emm.

 

JohnD, Yes, I did a little research before posting on here.. “2,500 to 128,000 pulses per mile.†As quoted on your link adds to the confusion. In any case not what I was looking for. Thanks.

 

Nick, I was looking at these HUD;s and saw they work with a OBD II signal, hence the post:

 

http://www.ebay.co.uk/itm/like/251354796048?hlpht=true&ops=true&viphx=1&lpid=95&device=c&adtype=pla&crdt=0&ff3=1&ff11=ICEP3.0.0&ff12=67&ff13=80&ff14=95

 

Hi, Motov8id and Chris, as you have guessed now I don’t want to change the speedo, but thanks for the links.

 

Craig, that’s a lot of instrumentation and I do like the 270° span fuel and water temperature gauge in C°.( I dislike the Fahrenheit scale, but like the PSI scale.)

 

A little time spent googling, revealed several phone apps that can do what I initially wanted and this one appears free:

 

http://www.digitaltrends.com/cars/hudway-unveils-iphone-based-head-display-app-free/

 

So, off to ITunes to download all the free ones and off to the cellar to find the mirror window film to cut a small piece off for the windscreen!

 

Just need to get the Spitfire back so can try it. Will try on the GT6 first I guess.

 

Cheers,

Iain.

 

 

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Ah, interesting idea. So would that box of tricks need to be plugged into you OBDII socket all the time (always assuming you had one to plug it into)? Not so keen on that.....

 

Smart phone solution (with gps speedo presumably) seems like a better and cheaper solution if you have a smart phone. (Luddite Nokia 9310i user here!)

 

Nick

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