Section : Dashboard Restoration

Electronic Speedo Conversion

Posted By : Jonathan Binnington, 03-May-2007, 09:27pm

• Electronic Speedo Conversion

  Posted By : Stephen Weblin, 03-May-2007, 09:49pm

  My first port of call would be these people. They used to be Smiths Instruments. Could repair/recalibrate any intruments when I last spoke to them, however that was a few year back now.
  
  Speedograph Richfield Ltd
  Rolleston Drive, Arnold, Nottingham, Nottinghamshire NG5 7JR
  Tel: 0115 926 4235

• Electronic Speedo Conversion

  Posted By : Chris Taylor, 04-May-2007, 07:27am

  Could try these guys http://www.jdo1.com/Speedometers.html
  They do conversions from mechanical to electronic tacho conversions (remarkably cheap!) but not sure about speedos. You'd need to work out what to take the drive from. Most moderns seem to have some form of sensor (Hall effect?) in the crownwheel area, although something mounted on the propshaft flange (with two sensors at 180 degrees, or 3 at 120 degrees if necessary to get the right sort of signal input frequency to get a smooth output and put the numbers in the same sort of ballpark as a modern one) would be more convenient. Perhaps the sort of take off for electronic ignition or injection from a crank position sensor could be adapted.
  You MAY find it simplest to retain the cable drive for a mechanical odometer, with electronic speedo.

  • Electronic Speedo Conversion

    Posted By : Jonathan Binnington, 04-May-2007, 08:01am

    what's hapened is that the nylon gears inside the overdrive of my newly fitted and otherwise nicely working and oil tight gearbox have stripped
    
    I think the probable cause for them stripping is the tortuous path the speedo cable needs to follow (so the teeth strip will probably happen again at some point
    
    anyway, the choice seems to ne a heavy and undesired job lifting the gearbox out again (already spent two weekends troubleshooting this fault) or driving the speedo some other way.
    
    I have also found the manufacturing company for Smiths electronic lookalikes in south wales, Hall effect transducers could run off the drive flange bolt heads
    
    will keep all posted
    
    j

    • Electronic Speedo Conversion

      Posted By : Vin Poonwassie, 04-May-2007, 08:21am

      an accurate speedo? now there's a novelty!

      • Electronic Speedo Conversion

        Posted By : Hugh Glossop, 04-May-2007, 09:27am

        First off do you have a 90 degree angle drive (you should with an overdrive) if so its normally those that strip.
        
        If you have no angle drive that is probably why you have a tortous cable run and to stay with a cable you will need one.
        
        Just in case.
        The gear on the output shaft is metal, the one on the drive pinion is plastic its very unlikely the metal one has gone, if so the dive pinion can be simply undone and pulled out without stripping the box.
        It may be a lot esier and cheaper to fix the cable system than go the electronic route. Dont forget to reroute the cable with the correct angle drive.
        
        have fun its a triumph
        
        
        hugh
        
        P.S electronic speedos also go wrong and are 10 times as expensive to fix, on my range rover the sensor ( which is driven off the cable output) is nearly £60 on its own

        • Electronic Speedo Conversion

          Posted By : Jonathan Binnington, 04-May-2007, 02:05pm

          Hugh, that's very helpful, I expected the scroll gear on the OD output shaft to be nylon like the gear that it drives, and had visions of needing to strip the overdrive to try to replace the scroll gear as well.
          
          the thought of avoiding £150 for an electric speedo and just having to replace the driven gear may provide the needed motivation to do this again
          
          the gears in my angle drive are metal, steel and brass so I'm not expecting them to have stripped
          
          but next good weekend weather I'll have yet another look
          
          j

    • Electronic Speedo Conversion

      Posted By : Paul Carter, 04-May-2007, 09:46am

      johnathan,
      
      as a quick fix while you decide get yourself an electronic pushbike speedo(seriously),i had the same problem some years ago and as i couldn't be arsed to remove the gear box at the time i tried one and it worked fine.all i had to do was fabricate a bracket to hold the sensor to on the steering arm and run the wires back to the dash.it works with one magnet stuck inside the wheel and you can callibrate the speedo down to the nearest mm wheel diam.i wanted to now it's top speed so i ran the bare wires down a rough file to simulate the triggering and it topped out at 250mph!..........

      • Electronic Speedo Conversion

        Posted By : Tom Longley, 04-May-2007, 02:10pm

        Hi, I used a company called Speedy Cables (http://www.speedycables.com/) and they were quite helpful. They should be able to retain the appearance of the original mechanical speedo but with modern electronic innards. As I'm sure you know, you attach magnets to the propshaft and an electronic-eye sends the information to the speedo. This eliminates the need for the old angle-drive and cable etc, as they are no longer needed.
        
        Let us know how you get on....
        
        Regards,
        Tom

        • Electronic Speedo Conversion

          Posted By : Alan Madin, 04-May-2007, 02:45pm

          I have similar problem on my 1300 Spit. Just spoke to Speedycable guys, well girl actually - they are working on about a 20 day turnaround, just under £220 plus P&P for conversion and new sender unit.
          mmmm....
          Al M

• Electronic Speedo Conversion

  Posted By : Leon Guyot, 04-May-2007, 04:50pm

  Speedy Cables.
  
  They did my Herald and my Vitesse.
  
  Very nicely
  
  Rgds
  
  Léon