I only see 2 wires from the motor which tells me its a brushed motor and since it works fine then keep it. Brushed speed controllers are alot cheaper these days since brushless is the next big thing. I raced electric cars for 7 years and alltho reverse was illegal to use racing it was common in alot of cars just for fun and the convenience of not having to chase after the car if u got stuck lol. What u would need is a trasmitter either stick or pistol grip (commonly used for cars) and there would be advantages to both. In this set up i personaaly would prefer a stick type controller for several reasons. 1) if you centered your throttle stick and had an esc with reverse then you could control how fast and which direction the line went . 2) once you set the stick at the right speed you could go completely hands off and let it go. you would also need a 1 or 2 channel reciever ( go with a 2 channel eaasier to find and same price. you would also need nicad batteries. Since the invention of lipo batteries also the next big thing these should be cheap as well so. With a cheap transmitter, cheap speed control, reciever and cheaps batteries it would most likely be a cheaper way to go. If you really wanted a clutch assembly you would only need a few pieces from a pan car like a 10L . you would need an axle (for a pan car) 2 differential rings a spur gear ( large gear on the axle) some small differential balls and light grease. and a smaller pinion gear for the motor. You would also need 2 bearings and bearing holders. It may sound like alot but it isnt. If the motor started to fast the differential would slip a bit depending on how much you tightened or loosened it so you wouldnt have to worry about overamping your motor or speed control. look at atem #966942 and ofer the guy 20 bucks for either radio and reciever shipped and the radio part is done. I dont know the guy im just saying for 20-25 you could have the raqdio and reciever. item 966914 in radio equptment is asking 40 + shipping for a reversible esc i dont know him either but id see if hed take 20-25 shipped. if it were me id buy the radio and esc and a battery or 2 and leav it at that. Also if you clever enough you can probably find a cheap radio shack car and get most everyhting you need in 1 stop. You dont need fancy i end stuff cuz if anyhting goes wrong u can just pull the plug lol. In fact now that i said that i would really try that. its highly possible you could buy a cheap rc car that goes fwd and reverse. Take the body off take the wheels off( leave the hub if it helps you mount it to your pulley) mount the drive axle to you pully and operate the whole thing the same as you would the car with everything built for you and all that you would need to do is figure out how to mount your pulley to the drivetrain. try radio shack toys r us wallymart and look for a cheap car or truck that does what u want and your good to go. Alot of choices. didnt mean to get windy but though of the cheap rc car thing afterwards lol. good luck with the project . Let us know how it turns out. Gary