Apologies if this is already a well known technique - while servicing a brake caliper with a couple of reluctant pistons I stumbled on the brill idea of using a cycle track pump with one of those lilo inflator adapters inserted in the union hole to persuade them to release their grip . More controllable than an air line (in my hands anyway) and easy to use. You're welcome
It's literally a socket of whatever size and then the square end of a socket drive... just so they wedge in. It just allows the stuck pistons too rotate. Once they budge you can slowly pull while twisting. I couldn't use an 'air' method as I had to split the caliper to get the pistons out, so they weren't air tight...
Water pump pliers are a cheap and surprisingly useful addition to a toolbox....... Mine have done as much nut strangling as plumbing.
Sorry, I meant no disparaging towards your method! And, I don't know about anyone else but as I go on this "bike repairs learning curve" it's all about getting skills and techniques in your armoury! The track pump method is certainly one I'll add to my list...so thank you. I didn't realise a track pump would give enough pressure....so it's certainly a good one to now know! When I first saw the twisty socket method...I was so blown away (apologies, married, mortgage and kids, so very easily pleased) I simply wanted to share it with as many people as possible!! Apparently it works on totally seized pistons...at least to get them turning, once turning you get some lube in there and end up getting them out...plus you are working on the inside of the piston so don't risk damage. Albeit, if their that seized, perhaps it doesn't matter. Eitherway....god bless us all as we weave our wonderful ways...safe riding!