I am replacing the rear brake pads and cannot get the caliper to compress. on a 2005 grand prix.

Rear Discs?

You screw in the caliper piston-- the pads will fall in there,
then ratchet up the park adjuster, when all is back together

No ----you should not have left them alone

You should always be taking things apart
to continue the learning process

Hello, my name is brad and im here to help.when you install your new rotors and pads,you had push in the calipers,did they push hard or fast,if hard you have stickey caliper,if not a colapst brake hose.hope this helps,have a great day and thank you.

Remove wheel, remove the two bolts in the calipers, spread and lift off calipers,
remove pads compress caliper piston with a c-clamp, be sure to have the brake fluid cap off the reservoir under the hood. - replace pads and reverse the order.

Remove wheel, remove the two bolts in the calipers, pull up calipers,
remove pads compress caliper piston with a c-clamp, be sure to have the brake fluid cap off the reservoir under the hood. pull the rotor off and put the new one on. - replace pads and reverse the order.

they look the same. your problem is either an emergency brake thats locked or a bad wheel bearing thats locked up. have you smelled brakes burning? if so,then i would say a brake issue. if not have you heard a squeling sound coming from the rear of car? if so then wheel bearings bad. either way the tire has to come off to look and see which it is.either one of these solutions can be your problem. hope this helps and thank you for choosing fixya.com

Just use one of the old break pads and a C-clamp of proper size like a 3-inch for compression on the cylinder.......Hope this helps.

Removal & Installation Front To Remove:

1. Inspect the fluid level in the master cylinder reservoir. Remove fluid from the reservoir until the level is lower then half way between the MAX and MIN levels.
2. Remove the tire and wheel assembly.
3. Install 2 wheel nuts to secure the rotor on the hub.
4. Remove the bottom brake caliper pin bolt.
5. Pivot the brake caliper body upward and secure out of the way. Do NOT disconnect the hydraulic brake flexible hose from the caliper.
6. Compress the piston back into the bore using a C-clamp. Figure of brake assembly with caliper raised showing brake pads in mounting bracket
   
   
7. Remove the inboard and outboard brake pads from the brake caliper bracket.

To Install:

1. Install the brake pad retainers and both brake pads into the caliper bracket.
2. Pivot the brake caliper down over the brake pads and into the brake caliper bracket. Insert the lower brake caliper pin bolt and torque bolt to 70 ft-lb. (95 Nm).
3. Reinstall the tire and wheel assembly.
4. Lower the vehicle.
5. Refill the master cylinder. Pump the brake pedal several times to seat the pads against the rotor.
6. Check the master cylinder level and add fluid as necessary.

Rear To Remove:
Rear disc pads R&I

1. Inspect the fluid level in the master cylinder reservoir. Remove fluid from the reservoir until the level is lower then half way between the MAX and MIN levels.
2. Remove the tire and wheel assembly.
3. Install 2 wheel nuts to secure the rotor on the hub.
4. Remove the upper caliper mounting bolt.
5. Pivot the caliper down to access the pads.
6. Remove the inboard and outboard pads from the caliper bracket.
7. Remove the brake pad clips from the caliper bracket.
8. Compress the piston back into the bore using a C-clamp and the old inner pad.

To Install:

1. Install new brake clips in the caliper bracket.
2. Install the inboard and outboard pads in the caliper bracket.
3. Pivot the caliper up over the pads.
4. Reinstall the upper mounting bolt and tighten to 32 ft. lbs. (44 Nm).
5. Remove the 2 wheel nuts securing the rotor.
6. Reinstall the tire and wheel assembly.
7. Refill the master cylinder. Pump the brake pedal several times to seat the pads against the rotor.
8. Check the master cylinder level and add fluid as necessary.

you can use a C-clamp

remove the caliper, by removing the two holding bolts, then use a old brake pad against the pistons and a c clamp and push piston all the way in, next is to clean and lube pad mounting surface and the caliper slide pin, then install new pads on bracket then caliper and tighten caliper bolts, heres a diagram to help you,

the rear calipers will have to be turned in(screwed in). do not try to push then straight in or you will have to replace the caliper