This article is one in a series that have been released in conjunction with Wayne's new book, 101 Performance Projects for Your Porsche Boxster. The book contains 312 pages of full color projects detailing everything from performance mods to changing your brake pads. With more than 950+ full-color glossy photos accompanying extensive step-by-step procedures, this book is required reading in any Boxster owner's collection. The book is currently available and in stock now. See The Official Book Website for more details.
Over the years, the parking brake on your Boxster may become unadjusted and fail to perform properly. The adjustment of the brake shoes that control the parking brake is an easy process, and shouldn't take you more than an hour to accomplish.
The first step is to raise the rear of the car and remove the two road wheels. This will allow you access to the rear calipers. Make sure that the parking brake lever is released and the car is in neutral. Using a screwdriver, push back slightly on the brake pads until the brake disc is allowed to turn freely on its spindle. Be careful to check the fluid level in the master cylinder reservoir, as pushing the pads back will make the fluid level rise and may cause it to overflow.
Once the brake disc can be moved easily, move to the cockpit of the car. Underneath the rear cover on the center console, you will see a rubber insert with a plastic panel underneath. Remove the rubber insert and the torx screw underneath, and pry up the plastic panel. Now loosen the two nuts that attach the handbrake turnbuckle so that the two cables become slack. If there is any tension on these cables, then it will be difficult to adjust the handbrake.
The adjustment of the parking brake shoes is accomplished by turning a small gear or sprocket with a screwdriver. Unfortunately, this sprocket can only be reached through one of the lug nut holes in the brake disc.
Rotate the brake disc until you can see the small adjusting sprocket through the lug nut hole (see Figure 1). You may need a flashlight for this procedure. Reaching in through the hole, use a screwdriver to rotate the cog until the parking brake shoe is tight and the rotor can no longer be rotated. It's probable that the cog assembly got turned around at one point when the shoes were replaced, so you will have to play with the mechanism a little bit to see if you need to turn the cog up or down to tighten. If you are turning the sprocket a lot, and the brake disc isn't tightening up, then you are probably turning it the in the wrong direction. Repeat this procedure for the opposite side of the car. After you have the sprockets adjusted so that the brake shoes have just pressed up against the inside of the disc, and you can no longer turn the disc, back them off nine notches, making sure that the disc can spin after the 9th notch.
Now move back to the cockpit of the car, and pull up on the hand brake several times to help seat the cables. Finally, pull up on the hand brake so that the ratchet clicks through two notches. Now, tighten up the cables using the nuts at the bottom of the handbrake lever. Tighten each of these nuts to the point where there is just a bit of slight resistance on each of the two rear wheels. Now, release the lever and verify that the wheels turn freely. The brake discs should be free to rotate with the handle in the down position, but fully locked by the time that the handbrake is pulled up a few notches past the two clicks.
When you are finished, recheck the master cylinder reservoir, and also step on the brake pedal a few times in order to make sure that the pistons have repositioned themselves properly against the brake pads. Also verify that the parking brake lamp on the dashboard illuminates as soon as the handle is pulled up (there's a switch near the base of the handle that triggers this lamp).
Removing the rotor reveals the mechanism for the parking brake adjustment. As the small cog is turned, the parking brake shoes are pushed outwards towards the inside of the disc. The proper adjustment of the shoes exists when the shoes are just about to touch the inside of the disc. The photo inset identifies the location of the sprocket when you are trying to look through the access hole in the brake disc: removal of the brake disc is not necessary for adjustment.
Shown here are the ends of the two parking brake cables wrapped around the turnbuckle. The two nuts that lock together need to be loosened (yellow arrow) prior to your adjustment process, and then tightened up later on. The two purple arrows show two screws needed to remove the entire console (required for Pelican Technical Article: Installing a Short Shift Kit and Replacing Shift Bushings).