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Rebuilding Brake Calipers
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Pelican Technical Article:

Rebuilding Brake Calipers


6 hours6 hrs






Flared-end wrench to remove brake lines

Applicable Models:

Porsche 986 Boxster (1997-04)
Porsche 986 Boxster S (2000-04)
Porsche 987 Boxster (2005-12)
Porsche 987 Boxster S (2005-12)

Parts Required:

Brake caliper rebuild kits, brake fluid, silicone assembly lube

Hot Tip:

Soak the caliper in parts cleaner overnight if possible

Performance Gain:

Better braking â€

Complementary Modification:

Replace the flexible brake lines, replace brake pads and discs
101 Performance Projects for Your Porsche Boxster

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.

If your car is pulling to one side when braking, then there is a good chance that you might have a sticky caliper that needs rebuilding. The rebuilding process is actually a lot simpler than most people think. It basically involves removing the caliper, cleaning it, and then reinstalling all of the components with new seals. Very often, the most difficult part of the task is the process of actually removing the caliper from the car.

The first step is to jack up the car and remove the caliper. Refer to Project 55 for details on removing the caliper from around the brake disc. Refer to Project 54 for more details on disconnecting the brake line from the caliper.

Once you have the caliper free and clear from the car, take it over to your workbench, and begin the disassembly process.

The first step is to remove each of the four pistons from the calipers. One method of removal is to use compressed air to blow out the piston. Using a small screwdriver, remove the dust boot that surrounds the piston. Place a small block of wood in the center of the caliper to prevent the pistons from flying out of the caliper. Blow compressed air through the caliper bleeder hole to force the piston out of its chamber. Start slowly, and gradually increase pressure until the piston reaches the block of wood. Make sure that the piston doesn't come all the way out of its chamber. After the piston is far enough out, you should be able to get a grip on it with your fingers. Be careful when working with the compressed air: as it is more powerful than it appears, and can make the pistons suddenly fly out of the caliper unexpectedly.

Using a rag to protect the sides of each piston, carefully remove all of them from the caliper using either your hands, or a large pair of vise-grips. Make sure that you don't touch the sides of the pistons with any metal tools, as you don't want to scratch this surface.

If the piston is frozen, then more radical methods of removal may be necessary. Using a block of wood, you can try pounding the half of the caliper on the block of wood until the piston begins to fall out. If the piston starts to come out and then gets stuck, push it back in all the way and try again. Eventually, the piston should come out of the caliper half. Another method is to use the car's brake system to release the pistons. Reconnect the caliper to the car and have an assistant pump the brakes to force out the piston.

Once the pistons have been removed from the caliper, carefully clean both the inside and outside of the caliper using brake cleaner or another appropriate solvent. All of the passages should be blown out with compressed air, and it's a good idea to let the whole assembly sit in some parts cleaner overnight. If the piston or the inside of the caliper is badly corroded or pitted, then the caliper should be replaced. A little bit of surface rust is ok: this should be polished off using a coarse cloth or some Scotch-Brite. Make sure that you thoroughly scrub out the entire inside of the caliper and the piston so that they are perfectly clean.

After the caliper and piston have been cleaned and are dry, coat the caliper and piston with silicone assembly lube. If you don't have this silicone assembly lube handy (it's available from, then make sure you coat the entire assembly with clean brake fluid. Do not get any lube or brake fluid on the dust boot.

Insert the new piston seal into the inside of the caliper piston groove. It should fit smoothly in the groove, yet stick out only slightly. Make sure that you wet the seal with a little brake fluid prior to installation. Now install the dust boot onto the piston, so that the edge of the boot is fits into the inside groove of the piston. Then, insert the piston slightly into the caliper. It should slide in easily: make sure that it doesn't get cocked. Push the piston all the way into the caliper. As the piston reaches the internal o-ring, you will encounter some resistance. Make sure that the piston doesn't become cocked as you insert it. If you have trouble inserting the piston into the caliper, you may want to softly tap it with a plastic hammer, or use a small piece of wood to compress the piston into its home position in the caliper housing. Finally, make sure the outer rim of the seal mates properly with it's groove in the caliper housing.

Install the brake pads (Pelican Technical Article: Replacing Brake Pads), and remount the caliper back onto the car. Bleed the brake system (Pelican Technical Article: Bleeding Brakes), and you should be good to go. Make sure that you carefully check the brakes on the car before you do any significant driving.

Remove the outer seal by simply prying it out of the caliper housing.
Figure 1

Remove the outer seal by simply prying it out of the caliper housing. The new seals are installed in reverse fashion, but may require some finesse work to get them properly seated in their grooves.

The best method I've found for removing the caliper pistons is to use compressed air to blow them out.
Figure 2

The best method I've found for removing the caliper pistons is to use compressed air to blow them out. Beware though: start with low pressure and then increase it if it's not enough. It's easier than you might think to send your pistons flying across the room with 100psi of air pressure!

Make sure that you replace the inner piston seal.
Figure 3

Make sure that you replace the inner piston seal. This seal is what keeps brake fluid from leaking out past the cylinder. Also be sure that you clean the entire inner cylinder for dirt, debris and corrosion. Don't scratch the inside of the caliper cylinder while you are working on it, or you may have problems with the caliper leaking when you reassemble it.

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Comments and Suggestions:
Sleepy Comments: and again
August 1, 2015
  Followup from the Pelican Staff: Thanks, got it. - Nick at Pelican Parts  
Sleepy Comments: not sure if the caliper pic link worked so heres another

August 1, 2015
  Followup from the Pelican Staff: No link here. - Nick at Pelican Parts  
Sleepy Comments: Morning from over the pond,

am i going mad or just incompetent - i was replacing pads and disks on my 2005 987 Boxster S and manage to tear a piston dust seal / gaiter when a piston dropped out.

I purchased the replacement part from my local Porsche Dealer and went to fit it yesterday evening but once it was on it looks very different from the existing ones as can be seen in pic below. New one on right

Have i been sold the wrong part?
Am i installing it wrong?
Did Porsche change the piston dust boots after the first years?

All help and advice greatly received
August 1, 2015
  Followup from the Pelican Staff: The seals do look different. i would your dealer double check the part number. - Nick at Pelican Parts  
Denis Comments: To my comment on the flared-end wrench size - turned out this is 10mm.
10x11mm is the right wrench for the job.
May 28, 2014
  Followup from the Pelican Staff: Thanks for the additional info. We appreciate it.
- Nick at Pelican Parts
Denis Comments: What is the size of the flared-end wrench to disconnect the brake line from the caliper on a 2000 Boxster S? Thank you!
May 15, 2014
  Followup from the Pelican Staff: If I remember correctly, it is 14mm. - Nick at Pelican Parts  
WGN Comments: Odd that you have this article on your site, which states "Make sure that you replace the inner piston seal", but two different members of your sales staff were unable to provide any help with the piston seals.
February 22, 2013
  Followup from the Pelican Staff: The parts are listed here:

The items you are looking for are dust covers. - Nick at Pelican Parts
Hatzenbach Comments: are you selling the inner seal?
I can't find it on the parts pages

July 20, 2012
  Followup from the Pelican Staff: If you give our sales department a call, they can track this down for you. The piston caliper seals are not available as a separate Porsche part - they have to be special ordered directly from Brembo. - Wayne at Pelican Parts  

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