ReadyShare storage - Safely Remove USB - drive not spinning down

I have an older WD "My Book Essential" external drive.  It connects fine with Readyshare. 

When I go onto the routerlogin.net Readyshare page and choose "Safely Remove USB Device", it shortly thereafter responds with "Now you can remove this device."  However the drive never "spins down".  Unlike when I directly connect the external drive to my PC (running Windows).  On the PC when I do Safely Remove and after I get the affirmation message, the drive shortly thereafter stops spinning and the power light on the drive turns off.  

When I Safely Remove from the router Readyshare, the drive is no longer shown, and the corresponding USB light on the router turns off.  So I go ahead and unplug the USB wire from the external drive, and then it does turn off.  I trust that the router has done whatever it needs to make sure there is no ongoing write activity and so far have not had any troubles with the drive after disconnecting it this way. (Unfortunately this model of the drive has no "off" switch.  On other models the power light was also a power button. I gather they did away with the power button because it is designed to just spin down automatically, but maybe they just got cheap in eliminating that extra hardware.  Thus I have to get to the back of the external drive and also tie off the wire so it doesn't slip away, an additional pain in the neck.)

The main trouble with this is that the drive continues to spin pretty actively.  It's not exactly quiet.  Occasionally the power light flashes. I don't think it would be wise for the drive to spin this way indefinitely.  WD has a utility to modify the delay before an external drives turns off, but that utility doesn't work on this older drive. I've let it go for a long time and it seems it's never going to turn off.

I'm thinking that perhaps the problem is that the USB port on the router is still powered.  I don't know exactly how the sleep states work, of course it needs to still detect when something is (again) plugged in.  I don't see anything on the router that would allow me to change how the USB might behave. 

Does anybody have any idea how I can get "Safely Remove" to work the same as when connected to the PC, so that the drive will spin down and power off?

(I noticed too that when connected the router shows the Readyshare as U: . I gather that is the drive letter being used within the router, I'm curious if I can do anything with that drive letter directly?  I have always done a "Net Use" or the equivalent to connect to the Readyshare.)