I meant long term, you ARE after that it seems. Tell me how well cleaning stops that. Oh! You already have.
Look here. The portion of the caliper BEHIND the piston seal ring is not the problem unless you are running mud for brake fluid. Need the fluid clean. Having that there will be no sticking there unless your outboard seals are worthless to allow 100% water penetration. That back can be utterly riddled with holes and work still for years. The portion the seal settles into, the actual groove MUST be in excellent shape or the caliper working simply sucks water in past it every time the caliper is backed off. That groove bad and the caliper is junk. The piston itself must be in very good shape as it slides inside the seal and chews on it every time a little pit crosses the seal, not to mention letting water go back the other way. The OUTER portion of caliper bore outboard of the seal can be coated with grease under the seals to delay sticking and often where the issue lies. In fact, the early calipers had no dust seal there whatsoever, the piston seal was the only seal on the piston. Honda just had you pack grease outboard of the piston seal to delay oxidation of the OUTER bore than made the piston stick. Yet like that they still go up to 3 years with zero issues, when sticking you simply clean it all out and grease the front edge of the piston up again, problem solved for 3 more years. BTDT on 3 bikes that sat outside in the elements 100% of the time.
New seals or o-rings are worthless without good non-pitted sealing surfaces under them, they leak instantly. The piston seal; it is imperative to have zero leaks around it as it then leaks brake fluid which by nature pulls water to it to corrode in 1/10 the the normal time.
Cleaning is great and how the problem is normally remedied, but that alone and you have issues again in less than 6 months. All you did was clean the aluminum so the water could find it bare to corrode easier. That actually adds to your problem after 3-4 weeks.
Maybe you can do something with that, applied in full I have brakes that don't leak, work fine, and last for years on many bikes and cars.
