RE: What do Clutch Bells do..??? and when you research spare clutch bell parts, what does the "T" mean..
[link=http://home.howstuffworks.com/chainsaw4.htm]link[/link]inside the clutch their are clutch shoes, the are on a hinge at the bottom or where the shaft of your motor is. when the motor spins it spins the clutch shoes and the top of the shoes begins to straighten and make contact with the clutch bell. once it grips the bell it turns the bell and turns all the gears. when your nitro car is idleing the clutch is not turning fast enough to get grip on the clutch bell but when you give it throttle the engine spin faster and puts more force on the outside of the clutch shoes. The T after the numbers refers to the number of teeth on the bell, the lower the teeth the slower your car will go and vis versa, be careful though because more teeth will make it harder on the motor and the motor will have to work harder to spin and you may run into tempeture issues.
here is a [link=http://home.howstuffworks.com/chainsaw4.htm]link[/link] that my help you understand a bit more (it is about a chainsaw clutch but they are hardly different.)