I'm trying to understand TV cable adjustments on 200-4R

Discussion in 'The "Juice Box"' started by TTNC, Jun 1, 2021.

  1. 12lives

    12lives Control the controllable, let the rest go

    Thanks Mart!
     
  2. GS464

    GS464 Hopelessly Addicted

    Nick:

    Here's the thing. Both the cable and the 'sheath' are of a fixed length. Neither changes its length by adjusting the sliding portion. The function of that adjustment actually pulls more or less of the cable out of the sheath, changing the position of the throttle valve inside the transmission before the carburetor linkage (and the attached TV cable) begin to move with application of the gas pedal. Think about how the brakes worked on the old ten-speed bicycles and others with cable actuated brakes and how that cable was operated. Same concept.

    Hope that helps.
     
  3. Ken Warner

    Ken Warner Stand-up Philosopher

    For what its worth that is the same position on the throttle linkage I'm using with my Fitech and 2004R TV cable. I went to great lengths to confirm the geometry by measuring the TV plunger travel at the valve body. Even confirmed it all with a pressure gauge when I was through.
     
    chrisg and 73 Stage-1 like this.
  4. jaystoy

    jaystoy Well-Known Member

    I did the same as Ken. I dropped the pan. Physically viewed the position of the valve at idle and at WOT. Once I was happy with that adjustment, I still verified oil pressures with a gauge, to verify idle pressure, and how soon pressure would rise off idle, as well as full-TV pressure. Critical to have pressure rise at the slight throttle pull. It's really not that hard.
     
    73 Stage-1 likes this.
  5. TTNC

    TTNC Well-Known Member

    Can the sheath move in and out of the trans once it is bolted to the trans case?

    My understanding is that you're supposed to prevent the steel braided cable from moving when you move the sheath forward or rearward. If the sheath doesn't move at the trans end, well that's why I made the sweatshirt sleeve comparison above.

    When you push the adjustor button, then move the slider all the way rearward, then manually open the throttle, the slider ratchets forward. What is making the slider do that if the braided cable moves independently of the sheath? One of them must be grabbing the other somewhere.
     
  6. 73 Stage-1

    73 Stage-1 Dave

    This visual might help... you can skip to the 2:10 mark.

     
  7. techg8

    techg8 The BS GS

    The sheath cannot move where attached to the transmission case.

    When you push the slider all the way rearward, you are increasing the sheath length between the trans case and the forward sheath mount. This removes slack or play between the throttle valve and it's a actuator bracket. In fact, it preloads the throttle valve a little bit.

    So there is no lash or slop or freeplay in the cable system at this point.

    So now when you hit the throttle, the metal cable is pulled by the throttle arm, depressing the throttle valve in the transmission further, until the valve bottoms out in its bore.

    At this point, since the throttle valve can go no further, when you continue actuating throttle at the carb, the sheath and slider will ratchet forward until WOT at the carb throttle linkage is achieved.

    In this manner it is assured that you have full throttle valve actuation at WOT carburetor throttle.
     
    patwhac likes this.

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