Solved, obsolete.

[evb149]

Solved, obsolete.

[zlymex]

I tore down this 5 inch hard drive in the similar hope but ended up in despair.  The spinning motor is a dedicated one and the voice coil is not useful to me.  There might be an encoder inside the motor but I cannot open it except to destroy it. Apart from these, I don't find other electro-mechanical parts. I had another 3.5 inch yet to be tear down.

[albert22]

I am pretty sure that getting specs for those electromechanical parts and motors would not be possible.
You will have to experiment, perhaps burning one or two. Also in some units, specially old CD/DVD drives, you can identify the bldc motor driver IC and get its datasheet
There are several projects on the web to drive HD motors. Here is one:
http://theamateurprogrammer.blogspot.com.ar/2014/02/revitalizing-old-hard-drive-motors.html