TH400 question

I have a TH400 in a partster that I plan to use behind a 350 Buick in my Jeepster. What controls downshift on these transmissions? Is it manifold vacuum? The only connection I can find between engine and transmission is a vacuum line.

 

Kick down is controlled by a solenoid in the valve body. There's an electrical switch that is attached to the carb and activated by the throttle on the Jeepster. On the Bullnose it attaches to and is activated by the gas pedal.

 

There are 3 things that control shifting on a TH400. Manifold Vacuum gives throttle position. The governor gives RPM. And there is an electronic kick down for downshift. The electronic kick down can be mounted in different locations depending on what vehicle GM, or whoever, stuck it in. Some have a switch under the gas pedal, some have it in the throttle linkage at the carb. I honestly don't know what Jeep used in the commando though. You can make your own with a microswitch at the carb linkage or under the gas pedal. There is a electrical plug on the left side of the tranny. The switch should close near full throttle. The rest of the shifting is handled with the Vacuum modulator and the governor. There are adjustable vacuum modulators to adjust shifting if need be, as well as the governor weights can be trimmed to lighten them up and increase the shifting RPM.
Greg

 

Thanks fellas. There's definitely not anything on the carb linkage. I'll have to check on the gas pedal.

 

There *might* be one on the gas pedal. I'm just not recalling seeing one mounted there. This is off a Bullnose, a Jeepster would look similar. If I get time I'll have a look in the parts manual.