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Speedometer woes

Discussion in 'Norton Commando Motorcycles (Classic)' started by joshtjeerdsma, May 22, 2018.

  1. joshtjeerdsma

    joshtjeerdsma

    Joined:
    Oct 11, 2015
    I have been breaking in my 72 combat restore and I am having a problem with my original smiths speedometer. It worked great for about 10 miles or so then just quit. I am worries that my new speedo cable was too long and went too far into the speedometer. Unfortunately I didnt read about cables being too long until after running it for a bit. I have since shortened the end protruding past the cable crimp from 11/16” to 9/16” and it seems to be the right length. The cable spins when the rear wheel is spun, but the speedo wont work with a drill attached to the drive end. If the speedometer did get damaged is there anything to try before spending the crazy cash to have it rebuilt? Thanks
     
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  2. kommando

    kommando

    Joined:
    May 7, 2005
    If it's been damaged from a overlong cable inner then no it's kaput.
     
  3. joshtjeerdsma

    joshtjeerdsma

    Joined:
    Oct 11, 2015
    Thats what I was worried about. Its frustrating that you can do expensive damage just installing a new part. I guess I should research the site before installing anything.
     
  4. kommando

    kommando

    Joined:
    May 7, 2005
    Treat it as a lesson learned and also never to trust any part, always check the part itself and of any known issues online before fitting. That these overlong speedo cables are still around after so many years tells you these are to be avoided and paying a premium to a known good supplier is worth it.

    http://www.speedograph-richfield.com/html/classic_motorcycle_cables.html

    There are NA alternatives with a good one maybe in Canada.

    Emgo is one of the suppliers of the overlong ones but it is an incestous business so may come in other boxes just to confuse.
     
  5. joshtjeerdsma

    joshtjeerdsma

    Joined:
    Oct 11, 2015
    Thanks for all the input. The cable was actually a Venhill that I purchased from RGM. Is that typically how they quit when the cable is too long? Work great for a bit, then just abruptly stop?
     
  6. trident sam

    trident sam

    Joined:
    Oct 23, 2012
    Normally using an over long cable results in the calibration being altered, ie the speedo will read a higher speed than the machine is doing. Have you checked the square hole in the speedo head, sometimes it's very worn and the cable just turns without moving the needle.
    sam
     
  7. Beach

    Beach VIP MEMBER

    Joined:
    Aug 27, 2013
    kommando likes this.
  8. kommando

    kommando

    Joined:
    May 7, 2005
    Beach has posted the Canadian source I hinted at but could not remember.

    The longer inner pushes the internals too close together and destroys possibly a bush or an aluminium plate, the site detailing the damage has been removed.

    You might be lucky and the square inside the speedo has worn large, some PTFE on the end of the cable can restore fit temporarily.
     
  9. Craig

    Craig VIP MEMBER

    Joined:
    Dec 20, 2005
    You can tell if damage caused by too long a cable by looking at face of instrument, if you see small brass bits/filings then , damaged by too long a cable and you need a rebuild , hope that not what you see ....
     
  10. joshtjeerdsma

    joshtjeerdsma

    Joined:
    Oct 11, 2015
    Well I think I may have lucked out. I shortened the cable a bit more and now the speedo works with a drill. It still doesn’t work when hooked up to the rear drive. So I think my problem now is that its not engaging enough in the rear drive since Ive shortened the cable. I will probably just shorten the cable housing a bit and hopefully be back to normal. Thanks for all the help.
     
  11. batrider

    batrider

    Joined:
    Aug 9, 2008
    There should a ring on the speedo end of the inner cable that limits movement so shortening one end of the cable does not affect the other end.
     
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