Boxster Parts Catalog Boxster Accessories Catalog Boxster Technical Articles Boxster Tech Forums
 
  Search our site:    
View Recent Cars  |   Cart  | Project List | Order Status | Help    
 >  >
Replacing the Brake Booster and ABS Controller
 
Bookmark and Share

Pelican Technical Article:

Replacing the Brake Booster and ABS Controller

Time:

3 hr

Tab:

$250

Talent:

***

Tools:

Brake bleeder, torque wrench

Applicable Models:

 
Porsche 986 Boxster (1997-04)
Porsche 986 Boxster S (2000-04)
Porsche 987 Boxster (2005-12)
Porsche 987 Boxster S (2005-12)
Porsche 987 Cayman (2007-12)
Porsche 987 Cayman S (2006-12)

Parts Required:

Master cylinder, brake fluid

Hot Tip:

Make sure that you keep all brake fluid away from your paint

Performance Gain:

Better braking assist

Complementary Modification:

Replace master cylinder, install stainless steel brake lines
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.

The Boxster is equipped with power brakes that utilize excess vacuum from the engine in order to assist with the pressure needed to apply the brakes. The vacuum is routed from the engine via a long plastic hose that runs up the side of the car, into the front trunk area, and plugs into a large circular brake boost canister that the master cylinder attaches too. After years of use, the rubber diaphragm inside the booster may leak or fail, causing the power assist function to lose its efficiency. In addition, this may cause an engine vacuum leak which can affect the proper metering of the fuel injection system. Before you replace your brake booster though, be sure that you check the vacuum hose connections that run to the engine to see if there are any leaks there (see Pelican Technical Article: Troubleshooting Vacuum Leaks).

The first step in removing the booster is to remove the master cylinder (see Pelican Technical Article: Master Cylinder Replacement). With the master cylinder removed, disconnect the three fittings from the top ABS control unit that were not attached to the master cylinder. Remove the ABS controller harness plug: the plastic tab on the side slides outwards to allow the plug to pull up and off. Pull the brake line pressure regulator out of its clip. Loosen the two nuts on either side of the ABS controller and lift the controller out of the retaining bracket, maneuvering around the existing brake lines.

Now move to the other side of the booster, near the front firewall. Remove the clip that secures the brake booster actuation rod to the brake pedal rod and separate the two (see Figure 2). New boosters have an updated design that includes an integrated boot and an internal screw. This change was put into place for cars manufactured after Sept 13, 1999, and to use the newer-style booster with the older cars, you need to update the brake push rod and the hardware associated with it. The process of updating the older cars is a bit of a pain, but instructions are documented in a 16 page Porsche Tech Bulletin Boxster 6/01 4770 031 (Brake Booster Seal at the Firewall Changed). See the 101Projects.com website for more information on this update.

With the booster rod disconnected, now disconnect the vacuum line on the front of the booster. Remove the two very long Torx T-45 bolts that secure the brake booster to the firewall. These bolts are the same ones that the master cylinder nuts attach to. With the bolts off, the booster should simply separate from the wall.

Installation of the new booster is basically the reverse of disassembly. With the new brake hardware in place, carefully bleed the brakes according to the instructions found in Pelican Technical Article: Bleeding Brakes.

In order to gain access to the linkage that connects the brake pedal to the booster actuator, you need to remove the alarm horn (purple arrow).
Figure 1

In order to gain access to the linkage that connects the brake pedal to the booster actuator, you need to remove the alarm horn (purple arrow). The upper right inset photo shows the vacuum hose plug that connects the engine vacuum line to the booster. Tug on this gently to remove it from the booster housing.

Use a set of wrenches to loosen up the connection between the booster actuator and the pedal cluster rod.
Figure 2

Use a set of wrenches to loosen up the connection between the booster actuator and the pedal cluster rod. This photo shows an early 2000 Boxster: later cars have a booster with a longer bellows. The photo in the upper right shows the booster and pedal cluster disconnected. In the upper left is shown the pedal cluster rod that must be changed if the booster is replaced with a newer-style one.

This photo shows what needs to be disconnected in order to remove the ABS control unit.
Figure 3

This photo shows what needs to be disconnected in order to remove the ABS control unit. Using a flare-nut wrench, disconnect the main brake lines (yellow arrow). Then, release the ABS electrical connection by pulling the connector release handle in the direction of the red arrows. Finally, unbolt the ABS unit from its bracket (purple arrow shows one of the mounting points).

Shown here is the front trunk with the master cylinder and ABS control unit removed.
Figure 4

Shown here is the front trunk with the master cylinder and ABS control unit removed. At this point, the bolts that hold the booster to the firewall have been removed, and the unit is ready to be removed from the car. The photo in the lower right shows the ABS control unit mounting bracket which needs to be removed so that you have enough clearance to pull the booster out (remove nuts: yellow arrows).

Here's the new booster and master cylinder installed.
Figure 5

Here's the new booster and master cylinder installed. At this point, simply remove the protective caps from all of the openings, install the ABS unit, reconnect the vacuum line, and reconnect the brake lines. Don't forget to bleed the entire brake and clutch system (Pelican Technical Article: Bleeding Brakes).

Bookmark and Share
Comments and Suggestions:
Shoey Comments: Good day Nick, thank you so much for your response. I am now fully convinced after three enquiries have all said the same. I'll be back if I have any more queries. Again many manh thanks. Regards Shoey
June 17, 2016
  Followup from the Pelican Staff: Thanks for the feedback. Glad we could help.
- Nick at Pelican Parts
 
Shoey Comments: Garage has told me I have a corroded brake pipe which needs replacement but can only do so by removing the PDK gearbox. I find this hard to believe can you confirm this is true please. Porche Cayman 2011 registration 2.9L
Chris Shoesmith
June 16, 2016
  Followup from the Pelican Staff: If the line is mounted to the body above it, it is likely true. - Nick at Pelican Parts  
Tim Comments: Hi there, removed booster from my 99 Boxster and it was full of water. Sure enough, the replacement TRW booster is newer style. Does 000-043-204-66-M100 kit make pushrods compatible and is that all I need? Your website is excellent...
July 14, 2015
  Followup from the Pelican Staff:
I do see an adapter in the kit, but honestly, I’m not the best with part numbers.

Give our parts specialists a call at 1-888-280-7799. They can figure out what part or repair kit you need.
- Nick at Pelican Parts
 
Tim Comments: Hi Nick,
As far as I know the rotors and pads are stock. I've had the car for 6 months - last two weeks brakes overly sensitive/grabby. Brake pedal would almost get sucked down when I touch it. I was driving in cold weather live in Canada.
November 21, 2014
  Followup from the Pelican Staff: Sucked down, ok. I would say, if it is all four wheels and not one axle or corner, the brake booster is a good place to start. Check that manifold vacuum is OK. If it is normal, you will have to check brake pad pressure, to determine if an axle is actually applying harder than another. This would rule out proportioning and direct you toward the booster. - Nick at Pelican Parts  
Tim Comments: 1999 Boxster - brakes feel really grabby - overboosted. Any ideas? Faulty booster? Thanks for any advice you can give!
November 20, 2014
  Followup from the Pelican Staff: Are the brake pads and rotors stock? - Nick at Pelican Parts  
Jim Comments: Pelican Parts website is absolutely the best for a Boxster owner. You have given me 'valuable' information and insight into the problems I faced with my '99' Boxster. I couldn't have restored it without you. Sincere gratitude.
November 3, 2014
  Followup from the Pelican Staff: Thanks for the feedback. Glad we could help.
- Nick at Pelican Parts
 
reclaimed bboxster Comments: have 1997 boxster and pedal was hard to push.. replaced booster. beed brake. now pedal still had to push and brakes are sticking... any ideas?
August 31, 2013
  Followup from the Pelican Staff: Is the brake booster receiving vacuum from the engine? i would start there. if it is, you can try cracking the front and rear brakes lines, then pressing the pedal to see how it feels. - Nick at Pelican Parts  
Jack Comments: I have a 99 Boxster and recently the brake pedal began sticking in the downward position with the brakes engaged. I have to place my foot under the pedal and pull it back up to disengage the brakes. I need help on troubleshooting this so I can repair the problem. I have read a number of post that lead to the brake booster. Any help would be greatly appreciated.
March 20, 2012
  Followup from the Pelican Staff: This could be a problem with the master cylinder or the brake booster. First check if the fluid is full. If it not, the master cylinder may have failed. There may be updated parts for your brake booster, as Porsceh made changes to them. Give our parts specialists a call at 1-888-280-7799. They can help you find the right part.
- Nick at Pelican Parts
 

  Search our site:    

View Cart & CheckOut | Project List | Order Status |  Help    

 

[Home] [Customer Service] [Shopping Cart] [Project/Wish List]
  [Privacy Statement]  [Contact Us] [About Us] [Shipping] [Careers]

Copyright © Pelican Parts Inc. -    DMCA Registered Agent Contact Page

Page last updated: Sat 12/3/2016 02:11:42 AM