POL 1958-64 ChevyImpala, Belair and Biscayne 13″ front drop spindle BIG Brake disc brake conversion kits are built to precise specifications and are shipped prefitted and assembled so you can rest assured that the brake system works properly. Performance Online’s disc brake kits feature dual piston Corvette aluminum calipers, drilled and slotted rotors and high performance brake pads. These systems not only upgrade your vehicle to discs, they also lower the vehicle a full 2″ without affecting steering geometry.