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48 Champion: "Downshift" Issue

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  • nvonada
    replied
    Testing with OD disengaged seems like a really good idea. This could be ignition dropping out too. Which could be the kickdown or something else.

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  • pjkush
    replied
    Thanks for your thoughts. Lots of moving parts for sure. Great idea on using a multimeter, i'll play with that. I shouldn't have to bend the paddle; if memory serves me, I had adequate room on the switch's threads to originally adjust it.

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  • jclary
    replied
    Originally posted by pjkush View Post
    jclary, now you have me thinking...how far in does the kickdown switch actually have to go to engage?
    Honestly...I don't know. You could take a multimeter, set it for continuity, and test it (static) to see how much the plunger moves to activate it. But, that is only one part of the equation. That switch just de-activates and moves the circuit to the two other wires to provide the "momentary" circuit break so the overdrive solenoid can disengage. Besides the switch itself, there is the condition of the accelerator linkage and the travel of the contact (paddle) for the switch plunger. That's the reason for the long threaded snout on the switch and the jam nuts to lock it into place. I suppose, if you run out of adjustment length, your next step would be to bend the paddle. Bending the paddle on the linkage would be my last resort.

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  • pjkush
    replied
    jclary, now you have me thinking...how far in does the kickdown switch actually have to go to engage?

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  • pjkush
    replied
    Thanks jclary for the additional tip and clear photos! I remember when I installed the new kickdown switch how touchy it was to adjust; perhaps I was a bit off or it has changed it's position slightly over time. I will take a look at that as well, and hope to report back a successful solution this weekend.

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  • jclary
    replied
    I have read the problem and suggestions to address it. If someone has discussed the mechanical relationship between the kick-down switch and how it mounts to the "kick-down switch bracket"...I must have missed it. So, I grabbed my trusty iPhone with its built-in camera and went to my cave to take a couple of pics of the linkage on my '48 Business Coupe. What you may be experiencing is a problem with your kick-down switch being adjusted just a tad too far in toward the "paddle" contact of the linkage. I will post two pictures. One will show the linkage contact mechanism at rest (idle) and the other much closer as when you are underway with the accelerator pedal pushed in maintaining traffic speed.

    The trick to preventing inadvertent kick-down is to adjust the switch so that the accelerator must be at maximum (floorboard) to activate the kick-down when chugging up a steep hill or passing a slower car. It is a very sensitive adjustment and there is very little movement one way or another to find the "sweet spot" to get the switch just right. When the switch is screwed into that bracket too far, it does not take much of a bounce of the foot while driving down the road to cause an unwanted kick-down. I know, I spent a whole afternoon one day monkeying with the one on my truck. I kept moving the switch too much when making adjustments. That's when I realized that it only takes a tiny movement (in or out) to get it right. If I'm successful with the pics, the two will be below. Hope this helps.
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    Click image for larger version

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  • pjkush
    replied
    Thanks for the additional suggestions! I will have a chance to try both this weekend and report back...

    ...I did check the OD cable today and it looks to be functioning properly - it is fully bottoming on the back land of the OD when pushed in

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  • altair
    replied
    I would suggest a process of elimination, firstly disconnect the OD kick down wire from the coil and drive it that way for a while. It won't kick down from OD with that wire removed, this is just a process of elimination. See if it stumbles. You will have to come to a stop to pull the cable for conventional drive.

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  • Dwain G.
    replied
    With the hand brake applied, wheels chocked, engine at idle speed, start wiggle testing all the overdrive wires. Wires around relay, kickdown switch, distributor, and on down to the transmission. See if you can induce a stumble or lurch.

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  • pjkush
    replied
    I will have a chance later today to check the position of the OD cable

    mapman - I believe it is only happening in OD. It most always happens at "higher" speeds (35-50) but it has also happened on occasion as I am slowing down to 10-15, but I seem to be freewheeling at that point vs. direct drive. ...and no unusual sounds at all; just the "jolt" of feeling like a downshift, then I continue to drive normally

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  • mapman
    replied
    does this happen in overdrive only or in direct drive too? Are there any unusual sounds at the same time?

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  • jackb
    replied
    make double sure that your OD cable (manual) is fully bottoming on the back land of the OD when pushed in....

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  • pjkush
    replied
    Greenstude - thanks for your response. I will try that on the speedo cable and report back! It does not rest on the switch but is close enough where it could certainly bump/touch it when driving. Hopefully it is just something simple like that...

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  • Greenstude
    replied
    For a guess, the kickdown switch or an exposed wire is grounding through the speedometer cable. It may not be touching all the time, just when some vibration brings the two parts together at speed..

    Years ago, the parking brake cable on my '47 Champion was grounding something so I put a piece of rubber tubing over it.

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  • pjkush
    replied
    Thanks - I just checked and all wires seem to be secure and in place. Some of the terminals were exposing a bit of wire but did not seem to be touching anything.

    I did, however, notice that the speedo cable was resting against the side of the kickdown switch. I never noticed that before when I replaced the switch. Could that be the cause? Is there a proper way to secure it out of the way? Perhaps to the firewall...but I don't see any obvious holes for a clamp to attach to it?

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