When you replace the caliper, replace the upper caliper pin and lower caliper bolt, too. These are critical in that the motion of the caliper on brake release must be extremely free of friction to let the weak "stubbing the toe" of the pad on the disc move the pads just out of drag range of the disc. Since there is no "return" spring to do this, the stubbing is the only force that moves the pad away. Any binding on the upper slide/guide pin and the lower guide bolt causes pad drag. It doesn't take very much drag at all to toast the caliper and cook the pads. I've had dragging pads get so hot they disintegrated in a stop, not a happy feeling.

Mitsu's seem unusually prone to this. On even just a pad change I pull the caliper off the upper pin and check and grease the surfaces of the pin and bolt with hitemp silicone brake lube. I do the same with the places where the pad edges slide on the spindle iron - file/sand/scrape smooth and light smear of grease. I have fairly successfull removed rusty spots from the pin and bolt with crocus cloth, but you have to be dead sure you get all the abrasive off, which is difficult with silicone grease mixed in. Make sure the rubber pin/bolt accordion boots are watertight. There's a metal cap on the back side of the caliper that closes that end of the caliper upper pin bore, with a pencil lead-sized hole in the end to keep the upper pin from having an air cushion effect in the closed bore. I make sure there's a blob of grease covering that, as it is the primary source of water ingestion in the pin bore and that's what causes the rusting problem. Every hanging mitsu caliper I've seen is caused by this or a close variant, a rusted lower bolt from a torn boot.

When you replace the caliper, replace the upper caliper pin and lower caliper bolt, too. These are critical in that the motion of the caliper on brake release must be extremely free of friction to let the weak "stubbing the toe" of the pad on the disc move the pads just out of drag range of the disc. Since there is no "return" spring to do this, the stubbing is the only force that moves the pad away. Any binding on the upper slide/guide pin and the lower guide bolt causes pad drag. It doesn't take very much drag at all to toast the caliper and cook the pads. I've had dragging pads get so hot they disintegrated in a stop, not a happy feeling.

Mitsu's seem unusually prone to this. On even just a pad change I pull the caliper off the upper pin and check and grease the surfaces of the pin and bolt with hitemp silicone brake lube. I do the same with the places where the pad edges slide on the spindle iron - file/sand/scrape smooth and light smear of grease. I have fairly successfull removed rusty spots from the pin and bolt with crocus cloth, but you have to be dead sure you get all the abrasive off, which is difficult with silicone grease mixed in. Make sure the rubber pin/bolt accordion boots are watertight. There's a metal cap on the back side of the caliper that closes that end of the caliper upper pin bore, with a pencil lead-sized hole in the end to keep the upper pin from having an air cushion effect in the closed bore. I make sure there's a blob of grease covering that, as it is the primary source of water ingestion in the pin bore and that's what causes the rusting problem. Every hanging mitsu caliper I've seen is caused by this or a close variant, a rusted lower bolt from a torn boot.