Botched brake job?

The rear brakes needed to be done pretty badly so I replaced both wheel cylinders, new Centric shoes, and all new hardware. Drove it for a day and all seemed well until I heard some clunking from the back right side....pulled the drum off and the shoes were cracked and a corner had broken off of one of them. Would this be caused by overheating? I double checked everything and made sure the adjustment screws were closed. Any ideas as to what I might have screwed up? Thanks in advance.

when i do it, i don't close the adjustment screws all the way, i tighten them up enough to take the slack out of the springs and shoes. then after i get the drums on i make sure they spin free. anything come apart in there? or did the shoe just fall apart??

overheating you will probably smell and see. either burnt paint on the hardware, or you will see the glazing on the shoes.
if everything elso looks OK, take the shoes back and get em exchanged. can't think of a auto store that won't take back stuff like that. most of the time they have AT LEAST a 1 year warranty on manufacturers defects.

Well I didn't smell anything, no smoke and everything was still in place when I took it apart, aside from the cracking/breaking. I'll take them back to the shop and get new ones. Hopefully some kind of manufacture defect like you said.

give your springs and stuff a once over too, make sure that they're back on the right way. what year XJ do you have??? i know mine's different then whats in the chiltons.