What is an anti roll bar?
The anti roll bar is also known as the roll bar, torsion bar, stabilizer bar, anti-sway bar or ARB. It is a metal rod with a length of about 12" and a ball joint connection at both ends. The ball joints at the ends rotate in different directions. At the top, the anti roll bar is attached to the shock absorber and at the bottom to the frame of the car.
The anti roll bar stablises the vehicle when cornering by decreasing the movement of the coil springs thereby avoiding that the vehicle leans so far that it starts to roll.