If your parking brake is not functioning properly, then perhaps it's time that you replaced your parking brake shoes. The first step in the process is to make sure that your parking brake cables and handles are adjusted properly. Refer to Project 51 for details on this procedure.
The parking brake shoes can only be inspected after the removal of the rear brake discs. Refer to Project 55 for the procedure for this removal. After you have the brake discs off, you can visually inspect the shoes for wear. The shoes should have some brake lining along the top and should not have any heavy grooves cut into them. Compare your brake shoes to the new shoes in the pictures in this project to determine if you need to replace yours.
After the brake disc has been removed from the brake assembly, remove the small parking brake adjuster by prying it out from between the left and right parking brake shoe. Make sure that the parking brake handle is all the way down for this procedure. Be careful while you are performing this removal, as the adjuster is spring-loaded and the springs may fly out when you are prying it out.
When you have removed the adjuster, take a set of needle-nose pliers and remove the long spring that that holds the left and right shoes together near where the adjuster was mounted. Again, be careful of the spring, as it may fly off unexpectedly. Make sure that you wear safety glasses during this entire procedure.
Now remove the conical spring-retaining mechanisms at the far left and right of the assembly. Press in the spring, and then rotate the spring so that you can slide it out of its slot in the back. You made need to stick your head around the backside of the axle carrier in order to see how to remove the hook on the end of the spring. Make sure that you don't lose the parts if they happen to fly out.
Now remove the long spring from the bottom of the two brake shoes. Use the needle-nose pliers again, and be careful not to catch your fingers in the process.
After the springs have been removed from the parking brake assembly, both the top and the bottom shoes should simply lift off of the assembly. The new shoe should be installed in an opposite manner to the removal process. Reassemble the parking brake by attaching the lower spring first, then the two conical springs, and then the spring toward the top. It's important to note that this reassembly involves quite a bit of maneuvering with your pliers and is not an easy task--you'll probably swear at the car a couple dozen times.
When you are finished, test the assembly by operating the emergency brake handle a few times. Carefully check the springs and make sure that they are properly seated in the restraining holes in the brake shoes. Loosen up the parking brake cables before you reinstall the brake disc and make sure that you recheck and adjust the parking brake mechanism (Pelican Technical Article: Parking Brake Adjustment - Porsche 911 Carrera) before you reinstall the caliper and the brake pads.
Remove the small adjusting cog assembly by using a large screwdriver to push it out from between the two parking brake shoes. With some effort, the cog assembly should pop out, leaving a little bit of slack between the two parking brake shoes. Be very careful when installing the new shoe, as the retaining springs have a tendency to snap out of place and fly out. Make sure that you keep your hands out of the way, and use safety glasses when installing or removing the springs. The inset photo shows a brand new parking brake shoe. Compare your old one to this one here in the photo to see if it needs replacement.
Using a pair of pliers, grab and unhook the parking brake spring from the brake shoes (green arrow). Be careful of the spring, as it is under a lot of tension at this point. Use a pair of vise grips and a pair of needle-nose pliers to twist the spring and unlatch it from the assembly. Also undo the small spring retainer (inset) that secures the brake shoes to the rear trailing arm. If you're not sure if your parking brake shoes are worn, take a close look at these (red arrow). The brake lining on this particular shoe actually looks pretty good and probably wouldn't warrant replacing.