Brake Caliper Disassembling Help

[5twins]

As far as C-clamp size goes, I'd say you want a big one, like 6" to 8".

 

[arcticXS]

I’m going to replace with stainless steel pistons

Then you could use a suitable size tap, to get a grip on the piston inside. Maybe 3/4 or 7/8 NPT or BSP pipe thread could work. Then grip the tap square i the vise, and tap on the caliper housing with a mallet.