I have a th400 that while the car is running, it wont come out of foward gear. Meaning that I drove the car a block down the street put it in reverse(whitch it hesitatted to ingage) then back into drive (went in fine) and when I went to put it in reverse agian it still drove foward. Now it drives foward in all gears. I've rebuilt th350 no problem. Any sagestions would help. And yes the linkage is all fine and working...

 

If it doesn't go into reverse you need to have it rebuilt. I believe there is a band that engages to hold the sun and planetary gear set when going into reverse. This band could be bad or somehow it isn't engaging. Start by dropping the pan to see if there is clutch material in the fluid.

 

Remove the pan and have someone move that linkage between the park and low positions, while you see if the selector valve moves accordingly.




Or you can listen to our resident trans expert,

Norm

 

I solved a similar problem in a Ford Cruise-O-Matic by adding a can of transmission " fixer" fluid . There are a lot of such transmission additives sold, all promising great things, but usually not solving the problem. However, in this case, and in one or two other instances I've encountered, the additives did free up stuck valve body components and saved a teardown. I consider it worth a try, and the additives don't seem to do any long term harm.