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Some people call it kickdown rod and some call it throttle pressure rod. Dont matter what you call it as it actually controlls what they call "throttle pressure" in the trans and since the throttle pressure is also sent to the pressure regulator it has some control over line pressure also.
To put is in simple terms the rod moves as you step on the gas and the more it moves the more throttle pressure is built up inside the trans. As you give it more throttle pressure it will raise the shift points and vice versa. It works like this.....the trans has shift valves in it that will move from side to side to control upshifts by sending fluid to the right clutch pack or band to make it shift. Now it is an automatic trans as it shifts automaticly. It does that by having the trans pump create line pressure that is sent to a valve that regulates pressure by the output shaft speed called govenor pressure and it also has another pressure called throttle pressure that is controlled by the throttle valve in the trans that is connected to the trans throttle linkage (kickdown). The trans basically shifts by having govenor and throttle pressures work on both sides of the shift valves. Govenor pressure is on one side of the shift valve trying to push the valve over to one side as speed increases to make the trans shift. The other side of the shift valve has throttle pressure that raises as the gas pedal is pushed. When you go fast enough that the gov press overcomes the throttle press it moves the shift valve over shifting the trans. Now if you step on the gas a very small amount the throttle press is low and it wont take much speed to shift the trans. But when you push the gas pedal down far the throttle press is higher and you need more road speed to get the gov press high enough to overcome the throttle press to shift. Thats why if you hit the gas hard the trans shifts at a much faster speed. Now when driving along at say 30 mph in third gear (727 trans) if you floor it the throttle pressure goes very high and it will overcome gov press and push the shift valve the other direction and cause the trans to downshift. Hence the term kickdown came about as it will cause the trans to kickdown to the next lower gear. Make sense ? Ron


good explanation, I learnt something new from that thanks