Needs help how to un-seized the rear brake piston. This is a turn-in brake piston instead of press.

I have proper brake piston presser (rotating style) that commonly sell from Amazon, Princess Auto, Harbor Freight, so it is not a heavy duty presser.

The brake piston presser does work in several cars, e.g. Mazda 3, Hyundai, Ford, Honda Odyssey, so I have a good understanding of how much force it uses to press a brake piston.

For this rear brake caliper, the piston is so much rusted that I can't turn it at all. I used a vise grip to run, but can't turn it as well.

I have spray WD-40 into the brake piston's rubber seal but still can't turn with the brake piston presser.

I viewed 2 days of YouTube video about seized brake piston, and no one is sharing much about rotating piston removal.

What other trick the member can share?

Note: I would like to keep the OEM brake caliper for environment-friendly purpose (not to become trash)

 

Meh. Either soak it in an unenviromentally friendly tub of evaporust, or just replace it.

 

Thanks Tyson to share the soaking idea. I will use damp cloth to soak those area. A have 2 acids available, i.e. vinegar and dead battery (HCI) that are environment friendly. 100ml of diluted acid should be enough. Hope not to see the brake caliper to become trash