I'm doing a brake job on a R55 and the car is up on jackstands with the transmission in neutral and the parking brake off but the front calipers are still grabbing hold of the rotor so I can't get the caliper off the car. I'm assuming it has to do with the hill hold but I can't figure out why it is still on. I've never ran into a caliper that won't just lift right off after it was unbolted!!!!!!

 

Try removing the cap the the brake reservoir? Doubt that will help but you will want to remove it anyways and some brake fluid to push the piston back in.

 

Could the caliper piston dust boot be cracked or torn? If so, rust/corrosion or dirt could be causing your caliper to be stuck, and you are looking at a rebuild. There's a thread on here somewhere on how to do that. Hope that's not the case, but it might be worth looking if the boot is cracked or torn. Good luck mate.

 

I have both sides off and each is the same. It is like someone is pushing on the brake pedal lightly

 

You might try just cracking one of the bleeder nipples open to see if some residual fluid pressure is being retained. I've had the inside of brake hoses delaminate and act like a check valve.

 

highly likely your worn rotors have a lip at the edge and you WILL need to push the pads/piston back far enuf to clear this lip. It requires no more pressure then you'll need to push the piston back for the new pads.

I'm usually able to get what I need by just grabbing the caliper and pulling it out, then pushing it in a few times FIRMLY - because these are floating calipers it works.... Or you can wedge a screwdriver it there and pry - no need to worry about damaging a pad you are going to replace but if you are not changing the rotors, keep them in mind

IME Disk pads don't retract when you come off the pedal, the pressure holding them tight releases and they end up floating in very light contact with the rotor. If there is a lip you need to open them up to clear . . . and MINI rotors IME form a good sized lip.