flex plate

[geraldchainsaw]

does anyone know what the flex plate does???

[CDN.SD]

The flex plate connects (bolts) the crankshaft to the torque converter, and delivers power from the engine to the transmission.

They also MAY provide the ring gear for the starter to drive, and a place for balance weights on an externally balanced engine

Hope that explains it.  

BTW, while they WILL flex to some extent, ideally, they won't if everything is set up properly.

[suede57ford]

The flex plate actually flexes some when the fluid pressure from the torque convertor pushes against the black of the crank.  Without some flex it could wipe out the thrust surface of the crank bearings.