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  • Auto box.

    My Cabrio 450 2002 auto box will not change up gears. But it will change okay when I change with the semi auto function. From this can I assume that is is probably the clutch actuator that is at fault and not the auto box itself. ?? Any help would be appreciated. [ Note if I rev very hard it sometimes changes up at high revs .] The box changes down as I decrease speed or use selector with no probs.

  • #2
    If it changes gears ok in semi-auto mode then the clutch actuator is fine. When you switch it into full auto mode with the button on the gear knob, does the display on the dash show "A"?

    The box changing itself up at high RPM (close to red line if you have a tachometer) and down at low RPM when in semi-auto mode is normal behavior.
    Last edited by mikerj; 27-12-18, 12:51 PM.

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    • #3
      Many thanks for the reply. Yes the A does show on the dash. The revs seem to go too high compared to when I got it and it seemed to change gears at a lower rev. It all went pear shaped after I did a run down the motorway at quite high speed.

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      • #4
        "The box changes down as I decrease speed or use selector with no probs."
        It's normal, that's how it works.
        How change upwards depends on which engine you have: diesel or petrol. And it also depends on the driving style. Maybe you should adapt the box, sensors and actuators .

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        • #5
          Is the engine getting up to normal working temperature? I've noticed that the gearbox hangs on to gears much longer when the engine is cold.

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          • mottofreee
            mottofreee commented
            Editing a comment
            The engine heat transmits the gearbox and the oil in it becomes much more fluid.
            Many garages change the oil from the box with inappropriate oil - usually with oil for manual gearboxes ... The Smart 450 manufacturer (Getrag) recommends ATF Dexron IID which is a thin oil.

          • mottofreee
            mottofreee commented
            Editing a comment
            The engine heat transmits the gearbox and the oil in it becomes much more fluid.
            Many garages change the oil from the box with inappropriate oil - usually with oil for manual gearboxes ... The Smart 450 manufacturer gearbox (Getrag) recommends ATF Dexron IID which is a thin oil.

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