TorqueFlite 727 Burned Front Clutches

I’m recalling a comment from almost 30 yrs ago so I cannot be entirely sure of what exactly was said. But I was told that the forward clutches are third gear. Third gear depends on the kickdown for proper line pressure. Without the spring the kickdown will remain in a position that drops line pressure. The lack of pressure means less force on the clutches and of course slippage.
On reassembly ensure the kickdown is assembled correctly and will travel to the furthest position in WOT and returns the the forward position completely whit the throttle closed. To eliminate any other issue put a pressure gauge on it when you first drive it. 60-90 psi is what you’re looking for.
Be sure the governer is free as that is what has taken out two of my transmission builds in the past.