Changing speedo gear to trick the computer?

i was just wondering what input the tranny uses to decide when it shifts. this would be on a 91' comache 4.0. i'm thinking the computer takes speed into account along with rpm and shifts accordingly. somehting tells me theres more to it though. is there any chance that a simple speedo gear change could trick the tranny into holding shifts a bit longer? i've got 31's on it and there's still plenty of power... it's got the "power switch" for the tranny that changes the shifts points and t/c lockup too but i was just curious to see if this is plausible? for example (not sure about this, maybe my theory is backwards but...) lets say you switch in a speedo gear to make the speed reading slower. as a result the tranny would think you were going slower and it wasn't time to shift yet. think it would do anything? like i said, i'm not sure what parameters are used so it may not do anything but i was just curious.

Nope.

Test your theory - disconnect the Vehicle Speed Sensor completely...it will still shift the same.

Jim www.yuccaman.com

There is no connection from the Trans computer (TC) to the vehicle speed sensor. Prior to 1998, the only inputs to the TCU are the Throttle Position Sensor (TPS), rear output speed sensor on the tranny, and the brake pedal switch. 1998+ will also have a front input shaft speed sensor.

You might be able to diddle with the TPS (a little adjustable for Renix Jeeps) to trick the TCU into thinking you're using more throttle and hence hold gear longer and downshift sooner.