TC – Traction Control
Traction Control System is where power to the driving wheels is reduced in the event of wheel spin. Unlike limited slip differential, where power is transferred to the opposite wheel that is not slipping, TC reduces overall power to the driving wheels. Effectively slowing the car down to reduce wheelspin. Of course, like most things on a Formula One car, this is all electronically controlled.
The main aim of TC tuning is to use only enough TC to stop wheel spin and drifting. No more, no less. This has the added benefit of preserving tire wear, but not sacrificing too much power.
Because TC in Formula 1 works by cutting fuel during wheel spin (that's mean reducing power output of the engine), always is recommended to use Limited Slip Differential settings first to try to stop wheel spin by transferring power to other wheel with good grip. If that phase is not successful and spin can't be stopped in this way, traction control should take over.
Finding the right TC figure for a F1 car on new track, is a bit of a trial and error effort on track or on simulators. On well known track, F1 engineers use data from previous events, and only a slight adjustment is needed if track condition change. They want to reach a point where the car is not loosing its rear end around slower corners, while still keeping the TC value as low as possible to get the most power to the road. Before 2008, during the start, TC was forbidden in F1 by FIA rules. From this year (2008) traction control is forbidden completely by same rules.
Remember, the aim of tuning race cars is to make it as fast as possible, not slow it down with TC. Let the driver do that.
In modern days, with sophisticated ECU control, engine manufacturer are trying to accomplish similar result as TC with engine torque mappings. The engine torque map is a theoretical model of the engine. It represents the torque output of the engine for a given engine throttle position and engine speed. As well as ensuring the engine behaves as it should, the map is also used to improve the driveability of the car for the driver.
9.3 Traction control :
No car may be equipped with a system or device which is capable of preventing the driven wheels from spinning under power or of compensating for excessive throttle demand by the driver.
Any device or system which notifies the driver of the onset of wheel spin is not permitted.