Attached is the only photo I have at this time of a metal bifold door pin.
It is bolted to the door with adjusting by sliding the door up or down. The pin is bent under the door.
To install/uninstall remove screws and pull/push door away from pin. The pin, whats left of it, is one piece. What's not shown is a threaded piece under neath that rides in the channel, there's no cap left.
Thank you for looking.
Larry