Fimum Fit,

You bring up a very logical point. In the drum brake days it was just common knowledge that when you replaced shoes, you cleaned, honed and replaced the kits in the wheel cylinders. If you didn't it was a virtual guarantee that you would be doing so soon afterwards.

Those cylinders pitted like crazy. Most calipers have stainless parts and the seal is in the cylinder rather than on the piston, or at least move with the piston.

Even with those old systems, annual brake flushing would have kept them in much better shape, and required much less trouble at brake time.

Have a great day,