Hi, I did a brake job after I bought my 2001 XK8. New pads and changed the brake fluid. Did a good job in bleeding the brakes, so I don't think that there is any air in the system.

When I first start the Jag, the brakes are "soft" and is very hard to get it to stop. After I drive it a block or two, the brakes are fine and remain that way all day even after short periods out of the car. I guess I could have a leaky internal "O" ring in the master cylinder that swells after it runs awhile.

Has anyone ever had this before? Any suggestions? Ron

 

If the pedal is always soft it's air. If it feels soft then gets better as the brakes heat up it's the pads. The only way anything in the hydraulics will swell is if there is a contamination of the fluid, such as oil. And once they swell they don't shrink/return to their previous dimension.