I've been wanting to build this so I could just compare same brand of motors against each other. The disk is a Futaba servo wheel glued to a Carrera pinion and I a Dubro clevis pin and threaded rod for the push bar. Not shown is the digital optical tachometer available for around $12 and the digital scale bought from Harbour Freight years ago. I'm not going to go through and do the math like Robert Livingston did, I just want to compare one motor to another.