What does the tranny kickdown cable really do?
#1
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Car: '91 Formula
Engine: 350
Transmission: TH350 built
Axle/Gears: 3.73
What does the tranny kickdown cable really do?
I put a Lokar Throttel cable and bracket on my car becuase Im using an LT1 Throttle body. You must use a Lokar transmission kickdown cable as well so I got one of those too. I put on the bracket and the Throttle cable last night but didn't have time to put ont he kickdown cable. Someone told me that all it did was to downshift the tranny at WOT so I figured I didn't need that. Well apparently it does a lot more. I figured I take it for a test drive to feel the throttle cabel with the kickdown cable just laid to the side. It would not shift out of first at all, no matter what gear I put the selector in. Finally I stomped on it and is shifted once really hard. I figured I might screw something up so I went back home. I have the kickdown cable and I will put it on tonight, but what does the kickdown cable really do.? Also I will need to adjust it properly as the Lokar one is adjustable. What do I look for there?
#2
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The TV cable on these is more than just a kick down cable like on a TH350 or something similar. These cables as you have found out totally alter the shifting points when not adjusted properly. This topic has been addressed but hard to find. Here is a link to one,(most likely not the most helpfull one).
https://www.thirdgen.org/techbb2/sho...ble+adjustment
Or do a search for cable adjustment and you will find more info!
Good luck!
https://www.thirdgen.org/techbb2/sho...ble+adjustment
Or do a search for cable adjustment and you will find more info!
Good luck!
Last edited by 85TPI400; 03-06-2003 at 08:18 AM.
#3
Calling it a "kickdown cable" is actually very midleading. It's actual name is a TV cable or Throttle Valve cable.
It slides a valve in and out of a bore to adjust the pressure which alters shift characteristics to better match the throttle position. For example, at low RPMs you don't need much pressure on the clutches to keep them from slipping, but if you were to increase RPMs and left the pressure the same you wouldn't go anywhere. It needs to increase the "grip" on the clutches in order to keep up smoothly with torque. Thus the valve.
Older transmissions like the TH350 used a modulator which measured vacuum in the manifold; an indirect indicator of throttle position. But when the pedal is floored it needed a seperate circuit to kick back down a gear which is what you need if you're flooring it. It's more or less an on/off deal. It's either kicking down, or not kicking down.
The TV valve is proportional, and very sensitive to it's position in the bore. If you have it adjusted incorrectly, you can ruin your transmission. You won't have enough pressure at higher RPMs and smoke some clutches, or you can have too much pressure and blow seals. Your short trip probably wasn't enough to hurt anything...much. You did say you stomped on it..uh oh..
It slides a valve in and out of a bore to adjust the pressure which alters shift characteristics to better match the throttle position. For example, at low RPMs you don't need much pressure on the clutches to keep them from slipping, but if you were to increase RPMs and left the pressure the same you wouldn't go anywhere. It needs to increase the "grip" on the clutches in order to keep up smoothly with torque. Thus the valve.
Older transmissions like the TH350 used a modulator which measured vacuum in the manifold; an indirect indicator of throttle position. But when the pedal is floored it needed a seperate circuit to kick back down a gear which is what you need if you're flooring it. It's more or less an on/off deal. It's either kicking down, or not kicking down.
The TV valve is proportional, and very sensitive to it's position in the bore. If you have it adjusted incorrectly, you can ruin your transmission. You won't have enough pressure at higher RPMs and smoke some clutches, or you can have too much pressure and blow seals. Your short trip probably wasn't enough to hurt anything...much. You did say you stomped on it..uh oh..
#4
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Car: '91 Formula
Engine: 350
Transmission: TH350 built
Axle/Gears: 3.73
Well I didn't really stomp on it to the floor, just enough to get it to shift though, and it did shift very hard. I did that twice and went back. Hopefully no seals blown, Im goint to install the cable tonight. So just adjust it so it shifts smoothly as before I guess.
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