When I got the van it had 89000 miles. When I went to change the brake pads I found the piston on the left caliper had a trianglular piece broken out of the edge. About 5/8 of an inch on all sides. Up to that time I had no brake problems that I new about. One day I took a ride about 100 miles and when I arrived the left wheel was HOT and smoking . Brake pads were dragging. Replaced caliper and pads,, caliper had same piece broken out of piston. Same area of piston, aligned with spindle...I have replaced rotor and calipers at least 3 times and am now going to garage to replace it all again. All pistons have piece broken out in the exact same place, aligned with spindle. After replacing every thing new, brakes work ok for awhile but eventualy start to drag after brakes applied. Rotor, caliper and pads are becoming exspencive. If pistons were made from steel like they were they would not break. One caliper lasted one week. but changed right away so I saved the rotor.