I recently purchased a c4 torque converter for my case fill c4 transmission. It is a used one the part numbers say it is a dynamic tct torque converter. When i installed it my trans will not engage and car will not move. I made sure multiple times that it was fully engaged in transmission. i contacted dynamic to see if it only fits certain years or models (case fill vs pan fill). They claim that the diameter of the torque converter input shaft is different between a few. Well i pulled it back out and measured it and the diameters are the same but the length of the input is 1/2 inch difference between the two. I attached a picture i wich you can see the difference between the two. The black on is the dynamic tct the blue is the b&m that works as it should. Any help appreciated thanks.
The shafts changed sizes a few times during the C4's life.
What year C4 do you have?
Do you know who the original owner of the converter is?
If so, call Dynamic with that info and the numbers stamped on the shell. It might be a custom stator that was installed for a specific application.
I would also pull out the input shaft and stick it in both converters to see if there is a depth difference.