@
FrickingReallySlow
It's somewhat normal to have slightly uneven pad wear on sliding calipers. It's part of the trade-off of the design. Looking at your image (assuming that's your caliper on the bottom), I don't see a sign of abnormal pad wear.
The pins aren't necessarily supposed to rotate. They should just be able to slip in-and-out with some ease to enable the bracket to adjust to the pad position. I would associate initial pin seizure with excessive heat/wear due to the pads unable to release contact with the rotor. I would also check the condition of your brake fluid and ensure there isn't any grease or contaminant on your pad/rotor system for loss of braking power.
- Are the dust boots still in good condition and intact?
- Dirt and dust getting into the grease and contaminating it can cause the pins to seize.
- Have you or the previous owner repacked the pin grease before the seizing occurred? What kind of grease are you repacking those pins with?
- It's a known issue that improper pin grease will cause swelling of the rubber and seizing
Hard to say if you need to replace the bracket. I doubt it though. You'll need to make that judgement call once you get them apart. You could opt for brackets or calipers from a wrecked car, remanufactured ones, or new ones if you need peace of mind.
With regard to your caliper pins seizing, I'm not sure the potential cause. I have never had an issue with any of mine in 120k miles of ownership. I've only had to maintain/replace them once at around 100k miles plus track days. I never had trouble pulling mine out or spinning them, and they moved just fine. During the maintenance check, I did replace a couple of the bushing inserts due to wear/cracking as well as a few torn dust boots, but they didn't give me any trouble. I got some off-brand ones that fit the system from my local auto parts store, which fit fine. I later overhauled a totally different set of rear calipers from another track car using the OEM Toyota/Subaru rebuild kit, which also went smoothly and easily. Note that both these sets saw decent track time, they saw a lot more heat and load than they typically would on the road.