A center door assembly for a dump bed and a method for removing the door from the dump bed. A frame is mounted in a wall of the dump bed and has a pair of opposite and spaced apart channels. A pair of elastomeric inserts are removably mounted in the channels. A retractable door has a pair of edges slidably received in the inserts and is movable linearly within the channels between a closed position and an open position. A pivot linkage assembly is operatively connected to the door for linearly moving the door between the closed and open positions. The elastomeric inserts are removed from the channels through a bottom opening in the channels providing lateral space between the channels to enable the door to be removed from the frame. The elastomeric inserts are provided with bend areas enabling them to be compressed for removal from the channels.