I want to replace the rear brakes and rotors on my XJR 100 . Is there a thread that might assist me in the a do it yourself brake replacement?

 

It's very simple, remove the wheels, remove the 2 pins that hold the pads in the caliper and remove the 2 caliper mounting bolts.
You will also have to push back the calipers pistons to make room for the extra thickness of the new pads/rotors.
B4 doing that, remove some of the brake fluid
Nothing more complicated than that.
The 2 bolts are goint to be very tight.
A pair of rotors are $250 with shipping for your car

 

Here's a nice write-up:
https://www.jaguarforums.com/forum/s...ad.php?t=35063