rebuilding/reconditioning brake calipers

[Chiba]

I want to rebuild my brake calipers (all 3) - at least I want to do so to the extent that the rebuild kit provided by BMW allows. I've been told an air compressor makes the job a lot easier - to pop out the pistons - but is this an absolute necessity? If not, is there another way to get the pistons out of their housings without damaging anything?

Thanks!

[kimokk]

Since you have to bleed the brakes anyway, just squeeze the brake lever to push the piston out then disconnect the brake line from the caliper.