There are numerous concerns over the internets about the idle timeout for the Western Digital Green Drives.
I’m going to show you how to open a Western Digital Elements 1Tb external drive and run WDIdle - to alter the drive spin down behaviour.
Opening the drive
The enclosure itself is made of plastic and has no visible screws for access. A fine razor blade or scalpel can be used to carefully pry open the bottom cover. Take it each corner at a time, you shouldn’t need to use much pressure as the casing offers little resistance.
Once you are inside, simply pull the internals out from the edge furthest away from the connectors. It is held together by absolutely nothing.
The USB interface
One point to note is that this external disk is simply a standard WD10EADS disk with an additional logic board doing the USB<->SATA conversion. This is great news as if the board fails we can simply swap it out or move the disk into another enclosure. Caution: when you are putting everything back together later on, make sure the ground (sticking up metal piece) is touching the disk.
WD10EADS Green, nothing fancy. It has some nice little noise reducing bumpers which also hold the disk in place.
Connect it up to your computer and boot into a copy of FreeDOS with the WDIdle tool. I used this disk image with grub to save some time.