So I had my kickdown cable installed on the transmission but not connected to the carb linkage last summer and it shifted perfectly, nice firm shifts, perfect shift points. I noticed I had a SLOW MINOR leak in the kickdown cable last summer, but the fluid loss was minor and thought maybe I could identify the problem when I eventually connected the carb linkage to the kickdown. Well...I connected the cable to the carb today, checked the tranny fluid level, and took it for a 5 mile ride. First thing I noticed, it wasn't shifting as hard. Second, it WAS kicking down from third to second gear when I floored it:-). Third, i could have downshifted way faster than it did on its own with the ratchet shifter. Fourth, and most importantly, I had tranny fluid pouring out of the kickdown cable!!! Probably lost about a half quart total. I have a ratchet shifter and had no issues with manual shifting last summer, and I could get a solid chirp out of second on demand. So my mind has been made up to remove the kickdown cable completely, going back to the way it was. I am thinking just using a 1/2" brass expansion plug to seal the hole where the kickdown cable would go as I have read other people have done. Any tips or pointers or suggestions from anyone? I do know that the kickdown cable on a rebuilt TH350 serves only the purpose of downshifting at WOT, it will not affect shifting or damage the transmission in any way. The shifts points are controlled by vacuum.

 

On the TH350, the cable is a true downshift cable, not a throttle valve cable, so it only controls the downshift. Removing it only means that you must manually downshift. It will not affect shifts otherwise.

For completeness, I will point out that later transmissions like the 200-4R and the 700R4 use a TV cable and that one MUST be connected for the trans to work properly.