usually you use a clamp to compress the cylinder or a wrench to screw in but I've tried both ways and they are not compreeing
How do you get rear caliper cylinders to collapse back in. on 1996 Infiniti I30
Use a universal 'caliper' tool sold at any parts house. They usually work with a 3/8 drive extension. If it's extremely tight to turn 'in' , try turning it 'out' (counterclockwise) first , for about a 1/4 turn. May need to work it back and forth a little. If it still won't go in you'll hav to replace the caliper. Make sure whichever you do , that you have it lined up properly for pin on pad or you'll have spongy brake pedal and most likely no parking brake (or very weak).
there is a special tool to use on rear calipers...