I have a 72 Cutlass supreme with a TH350 I was having an issue were my trans was not shifting gears, from 0-40MPH it would shift only once.
I researched the problem and decided to remove and clean the Governor.
I replaced it and refilled my Trans Fluid and took it for a ride.
It now shifts all gears 1st to 2nd at about 25-30mph 2nd to 3rd at about 40- 45mph.
It still wouldn't down shift at WOT. The problem I am now having is after attempting to adjust the Kickdown cable it would downshift at WOT but after releasing the Gas peddle it wont release the Kickdown switch and when I accelerate the RPMs keep increasing up to and past 5000 RPMs.
It feels like the car is in neutral while pressing the peddle with very little acceleration.
I pulled over and checked the Kickdown cable, after pushing in and out on the cable I could feel the switch release.
I got back in the car and started driving again, It shifted fine again until I floored it, the same thing happened
The Cable is brand new so I'm thinking that the switch in the trans is sticking and wont reset once the accelerator is released.
My question: how does the Kickdown Detent release after letting off the gas, what is the sequence of operation in the Kickdown system
As always I appreciate any help
Thanks CO Members
Gary

 

There is no "switch". The TH350 kickdown cable operates a spool valve (called the Detent Valve) inside the trans valve body that routes trans fluid differently depending on the position of the cable and the fluid pressure coming out of the modulator valve. The first thing to check is to make sure the cable is able to move freely. If there's any binding or sticking, replace the cable. If that's not the problem, it could be the vacuum modulator, which regulates the line pressure that the detent valve controls. If that's not the issue, it's something sticking in the valve body.

 

Thanks Joe
I was finally able to find some videos on Youtube that show how the Detent is positioned in the Valve Body, I Replaced the Cable with a new one but maybe I need to lubricate it better.
The modulator is new also. I hope it is just sticking because of the cable. will post my findings.
Gary

 

As Joe suggested, I disconnected the Kickdown Cable from the accelerator Peddle and pulled it back through the Firewall, I squirted some silicone spray down the housing and pulled the cable back and fourth a few times. I could feel the detent in the Trans moving in and out with no resistance.
I reinstalled the cable and went for a test drive. everything now works as it should. You couldn't wipe the smile off my face, after owning this car for 28 years this is the first time it actually ran like it is supposed to.
Thank God it turned out to be just a sticky cable. I know when I installed my new speedometer cable I pulled the cable out of the housing and lubricated it before installing it. I should have done the same to the new Kickdown cable, Lesson learned