Sounds like you may not have all the clutch plates aligned and the drums are not fully seated. It's easier if the transmission is stood on it's tail. I usually put the front and rear clutches together on the bench and then install as an assembly. It's tricky as you have to align the clutch plates as well as the large drive lugs on the front clutch with the slots on the sun gear shell. When it is installed correctly the front clutch lugs will be flush or slightly below the edge of the sun gear shell slots.