Auto trans kickdown

[Paul G]

Auto trans kickdown linkage has a spring holding the linkage arm against the throttle.The linkage arm is slotted. What is the purpose of the spring, and why is the arm slotted and not a fixed length?

[maxwellwedge]

The slot permits the lever to operate the kick-down lever at part/full throttle. The spring pulls the lever back at reduced throttle openings.

[John_Kunkel]

The purpose of the slot is to prevent the throttle from sticking if the transmission linkage should bind up. Even with the linkage stuck full back the carb can return to idle because of the slot.

If the spring wasn't there the weight of the linkage would cause it to fall back and fool the transmission into thinking there was more throttle applied than there actually is, this would cause late part-throttle upshifts.

[Paul G]

I just never thought that the trans would fail in such a way to restrict the throttle from closing. Makes sense. I have to get mine squared away. I had to use a bolt in the slot to get back far enough to shift correctly. I have to lengthen the arm with the slot somehow. 

[Big Squeeze]

I just never thought that the trans would fail in such a way to restrict the throttle from closing. Makes sense. I have to get mine squared away. I had to use a bolt in the slot to get back far enough to shift correctly. I have to lengthen the arm with the slot somehow. 

It's not really about the transmission failing, it's more that if the kickdown linkage rusted, or got into a bind for whatever reason, the throttle would still close.......

[John_Kunkel]

There are also cases of snow/ice packing around and freezing the transmission lever on long flat highways where there isn't much change in throttle setting.

[375instroke]

I just never thought that the trans would fail in such a way to restrict the throttle from closing. Makes sense.

Perhaps the engineers at Toyota should have thought about a fail-safe design in their throttles.