guage replacement

Discussion in 'Airheads' started by arbalest, Jul 11, 2018.

  1. arbalest

    arbalest Been here awhile

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    I am using offset triple trees on my R90/6 sidecar rig. I had to move the guages forward some to mount them. The speedo cable was long enough to reach but the tach cable is now too short. On top of that, the odo crapped out. Speedo works, tripmeter works, odo, not so much. Has anyone replaced the mechanical guage cluster with the later electronic cluster? I really miss the tach. I am currently running a 32/10 final drive, looking to move to a 32/9 for better around town gearing.
    #1
  2. 100RT

    100RT Long timer

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  3. arbalest

    arbalest Been here awhile

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    This site is great for the odo, it does nothing to solve the too short cable tach problem.
    #3
  4. Wirespokes

    Wirespokes Beemerholics Anonymous

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    Sounds like a custom tach cable is in order. I can form the ends of the inner drive cable, but haven't made a custom outer housing. Seems like it would be fairly simple - perhaps shorten a speedo cable and attach the proper tachometer ends.
    #4
  5. Disston

    Disston ShadeTreeExpert

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    You can use any tach made for models 1978 and after. BMW switched to an electric tachometer. I think its a single wire to the coils and a ground?
    #5
  6. Wirespokes

    Wirespokes Beemerholics Anonymous

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    Good point Disston. The bmw electronic tachs (like all electronic tachs) require three connections - +12V, Ground, Signal (from the coil).
    #6
  7. arbalest

    arbalest Been here awhile

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    So, can I remove the mechanical tach from my cluster and replace it with the electronic tach?
    #7
  8. Wirespokes

    Wirespokes Beemerholics Anonymous

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    It can be done, but requires adding a wire to the coil from the tach. Doing it cleanly is the trick. And the added wire needs to be protected because if it shorts out, there goes the ignition. Otherwise, it bolts right in. You'd need to find a tach from a 78-80 because they still had the high beam light tunnel with the indicator at the bottom of the tach face. After that, the high beam indicator was in the center section with all the other indicator lights.

    Another thing - the electronic tachs have green numbers where the earlier ones have white numbers. The newer ones also have a white needle that's a different shape than the earlier orange ones. I suppose the white needle could be painted orange to help it blend in, but with everything else, it doesn't really make sense. It may be possible to install the earlier orange needle on a newer tach. That's a possibility. It's been a while since I've done one of these conversions.
    #8
    lucky6600 likes this.
  9. bodine003

    bodine003 Been here awhile

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    KOSO North America has nice units. My 76 airhead has a HD Dyna Sport front end and I aced the factory BMW gauges and used a KOSO speedo-meter only. triggers of a magnet on the front disc rotor. works great
    #9