E34 (89-95) > 530i 535i 540i. E34 (89-95) > 525i M20, 525i M50. E39 (96-03) > 528i 530i 540i. E34 (91-03) > M5. Caliper pins are a wear part, when the brakes are applied these pins slide into the caliper and slowly corrode and wear out, causing the brakes to not work properly.