Fluid exchange on the 2006 k12S ABS Brake Servo - K-Bikes.com - Excellence in Motion
LinkBack Thread Tools Display Modes
post #1 of 2 (permalink) Old Sep 16th, 2013, 2:31 am Thread Starter
Join Date: Nov 2007
Location: Irvine, CA, USA
Posts: 29
Fluid exchange on the 2006 K1200S ABS Brake Servo

Hope to share my thoughts about my recent experience with flushing the fluid from the ABS Brake servo in my 2006 K1200S. The old fluid I removed was brown and saturated with rust particles. (New fluid is nearly clear). I had never opened the brake system since I bought the bike new, but moisture gets in there somehow.

I was at 35000 Miles and went for another front tire change. BMW dealer told me that the front brake pads were at minimum thickness and recommended changing the pads. They also said that I needed to flush the ABS Brake Servo. It was then that the service rep told me that since I had not flushed the servo every 2 years (for $250), that there was a 40-50 percent chance that the servo would fail shortly after flushing the fluid.

Service rep told me the replacement servo would be $1800, plus installation. He also said that the dealer was working with a local vendor that would provide the dealer with rebuilt servos for around $600. Dealer suggested that I delay flushing the fluid until the rebuilt servo became available.

I spoke with one of the techs and he told me that the flushing procedures require the tech to open the ports from the brake handle and foot brake and pump new fluid through the input side of the servo, and then to open the bleeder valves at the wheel cylinders, and then use the pump in the servo to pump out the old fluid and replace it with new fluid.

Now I must admit that I am not a professional mechanic, but I learned years ago that when you bleed the brakes on a car that you put a 2x4 behind the brake pedal so you do not allow the brake pedal to go to the floor. The piston in the master cylinder normally only moves a limited amount because the pressure in the brake system limits its movement. This cause this area that the piston moves to be free of corrosion, but the rest of the system to have corrosion. If the piston seals run across the corroded areas that the piston normally cant go when the bleeder valve is closed, the seals get destroyed by the corrosion, and then you need to replace the master brake cylinder.

With that in mind I decided to exchange the fluid myself, but without running the ABS pumps in the servo. Using a vacuum brake bleeder, I vacuum bled the side of the servo from the hand and foot brake. There are three bleeder valves per brake system and all three need to be flushed until you get clean brake fluid out.

Then using a standard funnel ($1.99) (and not the $45.00 BMW funnel) and my wife to hold the funnel (dinner at Outback's when I finished) I vacuum bled the wheel circuits until the only thing that came out was clear brake fluid.

Since I did not run the pumps in the wheel circuits or use the hand or foot brake, I avoided any possible damage to the seals and the systems seems to be working perfectly well. Maybe I beat the odds and would have had one of the 50% of the brake systems that continued to work after the dealer flushed the fluids. Who knows, but I like the odds better if I vacuum bleed the system rather than relying on BMW procedures which very likely would have damaged the system.

Hope this help or is food for thought as you decide what to do with your brake system.

Lastly, the dealer told me that BMW changed the system in 2007 to a system less prone to failure.

Last edited by peterpeter211; Sep 16th, 2013 at 2:39 am.
peterpeter211 is offline  
Sponsored Links
post #2 of 2 (permalink) Old Sep 16th, 2013, 9:35 am
Join Date: Jun 2008
Location: New York, NY, USA
Posts: 676
Yes, BMW changed the ABS in 2007, so now instead of the pump failing the electric power circuits on the PCB fail.

Thanks for a nice write up.

2008 K1200GT, Custom Paint, Vivid Black, Aeroflow WS & Aeroguards, Givi E52 Maxia Topcase w/AdMore Lighting, Zumo 660, Suburban Footpeg Lowering, Sargent Seat

2009 R1200GS Adventure, Magnesium Grey/Black, Adventure Cases, Zumo 660, Touratech Unobtanium Accessories

1974 Norton Commando 850 Soon to be a restoration project
lhendrick is offline  

Quick Reply

Register Now

In order to be able to post messages on the K-Bikes.com - Excellence in Motion forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Please enter a password for your user account. Note that passwords are case-sensitive.


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:


Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode

Similar Threads
Thread Thread Starter Forum Replies Last Post
2006 K1200s - No ABS Brakes - Rear Brake Light Stays On colonial_buff K12/1300S 2 Oct 9th, 2013 11:34 am
18K Service - How many hours? Captain K12R K12/1300R/R-Sport 8 Jun 17th, 2011 12:18 pm
brake fluid change, ABS WayneDW Other K-Bikes Discussion 3 Feb 20th, 2011 5:18 am
Integral ABS and ASC - New Riding Dynamic Control Systems for BMW Motorcycles SilverRT K12/1300GT (Next Gen) 1 Jul 14th, 2006 4:09 pm
K1200RS, Brake Fluid Repl. with ABS and Integral sys. montes K1200RS/GT (Classic) 14 Apr 26th, 2006 12:44 pm

Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

For the best viewing experience please update your browser to Google Chrome