Brake Upgrades From XKs and Wilwood. While Jaguar was certainly at the leading edge of technology by fitting disc brakes in the fifties, many improvements have been made since. Our Wilwood brake conversion kits employ lightweight alloy calipers for a reduction in un-sprung weight and large gains in pad area. Supplied with all necessary adapters, hardware and streetable brake pads. A great complement would be a set of braided stainless brake lines, below. Kit includes four-piston calipers and mounting hardware with new pads. Does not include rotors. This kit will not show as being in stock but no worries; it is assembled from individual pieces when ordered.