I notice that if i try to get into passing gear it seldom does it. It that set up cable or vacuum?

 

If its a T350 trans it use a cable, if its a T400 it uses an electric switch. Both need to be adjusted to engage near or at WOT.

 

I assume a cable is adjusted at the carb? Electric????????

 

Should be n the gas pedal linkage inside by the floor.

 

how do I adjust if it is electric?

 

I think I remember you saying this is a 455 car; it will have a Turbo 400 or possibly a 375 (T400 with lighter duty internals, though those were mostly in 350-engine 88s with trailer package).

These transmissions are electric downshift and the downshift switch is inside the car, under the dash, top of the accelerator pedal. It can be adjusted.

Find it and push the lever on the switch all the way toward the firewall, then press the accelerator to the floor (engine OFF). The switch should follow the pedal and adjust. Take car out and road test it. If it still doesn't downshift, either downshift switch or the downshift solenoid in transmission isn't working. Also make sure the wiring is plugged up at both ends- look for a plug on side of transmission with an orange or orange/black wire.

If the solenoid is bad, I think it can be replaced by dropping the pan- which gives you opportunity for a transmission service at same time.


A 350-engine car should have a Turbo 350/375B which have cable-operated downshift (cable running down passenger side of trans) To adjust, disconnect it at the carb end (some years have a plastic tab you have to push in and release) and let the cable retract to the transmission. Pull it out far enough to reconnect it at carb and then open the linkage to WOT (engine OFF). This should set the kickdown cable for WOT downshifts. Road test.

If yer T350 cable is mucked up aftermarket replacements are available.

Good luck! Hope it's a simple adjustment fix!

 

I'll add to Glenn's very thorough description that ALL GM automatics used vacuum in 1974. The vacuum modulator did NOT control kickdown, it served as a sort of throttle position sensor that controlled upshift points. The kickdown solenoid (TH400) or cable (TH350) was the mechanism for the downshift.

 

I have a 74 with a 350 motor. No idea on the trans though.

 

Well as ya know my car is a 74 Olds Rocket 350 Conv. My car has the electric kickdown at the gas pedal, nothing coming off the carb. So I have a T400 trans. Is that a good trans?
I did the procedure listed above to set it. Will test it in the am
I did make sure the cable was connected at the pedal. I have not looked under the car at the trans yet. I know from time to time I could catch the passing gear but mostly I have not been able too.