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...The never ended story of my Smiths speedo

Discussion in 'Norton Commando Motorcycles (Classic)' started by yves norton seeley, Feb 8, 2020.

  1. yves norton seeley

    yves norton seeley

    Joined:
    Feb 13, 2014
    Hi Storm42,
    I am still waithing for the 3 wires sensor from Caerbont. I remove the Motogadged sensor and buy a sensor with 3 wires with Hall effect, this sensor don't need magnets, the sensor take is pulses from 4 steel bolts thats hold the rear disk rotor.
    The circonference from my BT45 120/80/18 is 2.025 meter and 4 pulses per turn give me 001975 pulses pro Km
    But nothing hapens, the pointer don't move.
    I decide to waith for the Caerbont sensor before I do the next test.
    I dont have a wire White with Black rings.

    Thanks
    yves
     
  2. storm42

    storm42 VIP MEMBER

    Joined:
    Jul 20, 2011
    Last edited: Feb 10, 2020
  3. Fast Eddie

    Fast Eddie VIP MEMBER

    Joined:
    Oct 4, 2013
    I once installed my pick up with a little too much air gap between it and the wheel mounted magnet. The speedo needle don’t move. Closed the gap a little, speedo perfect!

    Like Ralph, I have the Puca units. The wiring is amazingly complex and I hate fitting them (I’ve fitted two sets now) but each time, they’ve worked fine (air gap issue notwithstanding).

    Due to the complexity of the wiring, it’s easy to go down rabbit holes, and get stressed out, and go down deeper rabbit holes!

    I’d leave it for a little while Yves and try and come back to it in a few days with a fresh head.
     
  4. yves norton seeley

    yves norton seeley

    Joined:
    Feb 13, 2014
    To day I receive the 3 wires sensor made by Caerbont, the one with the led light in the pick-up, I put the sensor on the bike, the led light everytime one of the four disk bolts pass in front of the sensor.
    But the pointer is still dead....
    My parts provider Frank give me another Speedo, same one, I will try this one tomorow
    Keep you posted
    Yves
     
  5. yves norton seeley

    yves norton seeley

    Joined:
    Feb 13, 2014
    Hi Nigel,
    My air gap is 1.5mm at the moment, but I try different gaps W/O sucsess.
    You know me, only my broken hip can keep ma away from my workshop as I work more as 4 hours a day.
    I wish to find someone with a fresh head, my head don't understand the situation anymore.
    yves
     
  6. storm42

    storm42 VIP MEMBER

    Joined:
    Jul 20, 2011
    Yves,
    Is this how you have it wired? (minimum wires needed)

    Smiths.jpg
     
  7. yves norton seeley

    yves norton seeley

    Joined:
    Feb 13, 2014
    Yes this is how I have wired, I will take a day out tomorow, need some rest
    Thanks
    Yves
     
  8. storm42

    storm42 VIP MEMBER

    Joined:
    Jul 20, 2011
    You could try the black wire from the sensor with the Red/Black wire from the speedo but if it still doesn't work it looks like the speedo is broken.

    Also, I see the spec for the air gap for the sensor is 1mm to 2mm so at 1.5 that is good, which is proved by the light flashing anyway, I think you can be sure that bit is OK.
     
  9. yves norton seeley

    yves norton seeley

    Joined:
    Feb 13, 2014
    Thanks Storm, I will try the red/black tomorow, if not working, I put the new speedo
    Yves
     
  10. yves norton seeley

    yves norton seeley

    Joined:
    Feb 13, 2014
    To day I try the Black Wire from the sensor to the Red/Black from the speedo, notings happens...
    I put the other speedo that I receive from Frank, make the connections, try Red/blue and Red/Black, notings happens...

    Remember: my speedo is the one with the green dot, usualy for Commandos, and Commandos are positive ground but the Sunburst is negatieve ground???
    When I was buying the speedo, no instruction in the box, I mail the part # on the box to Peter at Caerbont and he send me instruction for negative ground. I belief now that the speedo with the green dot is for posietive ground only.
    Your opinion please
    Yves
     
  11. maylar

    maylar VIP MEMBER

    Joined:
    May 13, 2007
    The diagrams I've seen show two wires for power. Ground polarity shouldn't matter.
     
    MexicoMike and kommando like this.
  12. yves norton seeley

    yves norton seeley

    Joined:
    Feb 13, 2014
    I mail to Caerbont to be sure
    Yves
     
  13. storm42

    storm42 VIP MEMBER

    Joined:
    Jul 20, 2011
    I see Vercu has a negative earth Norton and a working speedometer, but hasn't said if it is a Norton specific one. You may be right about the Norton green dot being positive earth and I cannot find a specific diagram for the Norton clock, all the wiring diagrams I can find state the clocks are negative earth only.

    To speed things up I could ring Caerbont tomorrow for you and find out if this is the case.
     
  14. storm42

    storm42 VIP MEMBER

    Joined:
    Jul 20, 2011
    Just a thought, did you lower the PPU from the factory default on the new speedo for the test? mine didn't work until I set it to 800
     
  15. yves norton seeley

    yves norton seeley

    Joined:
    Feb 13, 2014
    If you can be so kind to ring Caerbont please,
    thanks
    Yves
     
  16. yves norton seeley

    yves norton seeley

    Joined:
    Feb 13, 2014
    I can try it to day
    yves
     
  17. kommando

    kommando

    Joined:
    May 7, 2005
    Unless the body of the speedo and/or the sensor are earthed then there is no need for -ve or +ve versions.
     
  18. storm42

    storm42 VIP MEMBER

    Joined:
    Jul 20, 2011
    I have a feeling they will work on either + or - earth, whilst there isn't much info on the speedo out there, the rev counters will work just by swapping the wires over according to the available diagrams. Having said that nearly all the available speedometer diagrams state negative earth only.

    Yves, I have rung them and got though to a lady who told me they are closed on Fridays, she did try to put me through to somebodies home number but they didn't answer. She was as helpful as she could be, but no banana!!

    She asked me to ring back on Monday which I will do.

    I did think that it looks like it should work on negative earth because you said you are getting the startup sweep of the pointer.

    Could Vercu confirm his is working on Negative or positive earth?
     
  19. yves norton seeley

    yves norton seeley

    Joined:
    Feb 13, 2014
    Thanks Ralph,
    I try 800 this morning, no changes...
    I reduce the gap to less than 1mm, no changes...
    Yves
     
  20. vercu

    vercu

    Joined:
    Dec 21, 2010
    My Norton P11 is converted to negative earth.
    For information: the ppu (km) number is set to 5792 for 2 magnets and an 18 inch rear wheel.
    Yves: just a tought: did you check the signal from the sensor with a multimeter? When turning the wheel by hand the resistance should switch between zero and full with the reed sensor. Sorry if that is too simple :)
     

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