The brake pads on your 1997 Jaguar XK8 use a friction component that presses against a brake rotor, which is a round disc that is mounted onto a wheel hub just behind the wheels. The brake lining needs to be inspected at least once a year to make sure that the lining has not been sufficiently worn down and that there are no score marks on the brake rotor's surface. Excessive scoring or damage to the brake rotor indicates the need to replace both the pads and rotors. However, if the rotors are fine, and the brake pad is one-eighth inch thick or less, you'll need simply to replace the brake pads.
Jack up the front of the Jaguar using the jack points on the front and rear of the vehicle. The front jack point is just behind the radiator and the rear jack point is behind the boot.
Place jack stands under the frame of the Jaguar and lower the vehicle onto the stands.
Unbolt the lug nuts on the wheels using an air-impact wrench and pull the wheels off the wheel hub.
Place a C-clamp over the caliper on the brake rotor. Orient the clamp so that the screw end of the clamp is towards you (so that you can tighten the clamp) and resting against the back of the brake pad in the open centre of the break caliper, and the fixed end of the clamp is secure on the back side of the caliper.
Tighten the clamp. This will push the brake-caliper piston back into the caliper (which is not visible at this point). Keep tightening the caliper until you cannot tighten the clamp any further.
Remove the clamp from the caliper and unbolt the bottommost bolt on the back side of the caliper using a socket wrench. This is the caliper's pin bolt.
Unbolt the upper and lower caliper-mounting bolts and slide the caliper off the rotor.
Swing the bottom of the caliper up and open the caliper. The brake pads will easily come out.
Insert the new brake pads with the same orientation as the old pads and reassemble the caliper. Installation of the caliper is the reverse of removal.
Lower the vehicle to the ground using the floor jack once the wheels are secure on the wheel hub. Pump the brake peddle several times to restore brake pressure to the system before driving.