Flushing ABS

[B4ndit]

I have a 2011 GS with ABS.

I can't quite get my head around the ABS flush procedure from what scant information I can glean on the forum.

Have I got it right if I bleed the brakes as follows.

Step 1) Bleed the front and rear brakes as normal.

Step 2) Reseal the system. Screw the reservoir covers back on.

Step 3) Flush the ABS with the GS 911. (I take it this moves the old ABS fluid in the ABS into the new fluid in the braking lines)

Step 4) Bleed the front and rear brakes as normal.

If anyone could enlighten me on what actually happens when the GS 911 flushes the ABs and how long it takes for the GS 911 to do it. Would be appreciated.

[mike d]

The GS-911 DOES NOT bleed the brakes. Yo have to do a complete bleed mechanically.

The GS-911 function is only to indicate if you have managed to get all the air out of the system.

If the test fails, then you need to separately bleed the system again.

Mike

[Haakon]

I believe "B4ndit" want to "change" the fluid trapped in the ABS unit?
I GUESS his initial bleed worked out ok? Many people worry for the ABS and bleeding it.
I do NOT want to start a new thread with discusion of WHY to do so!!!!

The ABS bleed is (what BMW says) only to be done when a ABS-N unit is replaced.
The Integral ABS units is made differently and work differently- no bleeding needed even when its replaced.

OK, so why bleed the ABS? (or replace the fluid inside)?
I have my ABS kick in a few times a week. That mean its partly filled with the old brake fluid.
I have had brake fades too often so when I change my brake fluid (once a year) I also flush the ABS.
Why not? But, also, that is me :-)
-------------------------------
B4ndit- you do it right. Bleed your brakes the way you did.
Then the HUGE question is if you want to bleed the ABS too???
If you got spongy (soft) brakes you did not do the regular bleed the right way- air is trapped somwhere.
A ABS bleed will never cure that.
 
If you want to bleed the ABS, remove the lids on both front and rear brake fluid reservoirs- cover the reservoirs with cloth or something.
(Brake fluid damage all painted parts)
Then do the GS911 bleed.
If you want to remove the fluid from the ABS thats now in your main brake lines, do another full flush of the brake system.
----------------------
My experience is that soft (spongy) brakes are mostly caused by air trapped in the top of the front brake pump banjo.
Turn the handlebars fully left. While have a slight pull on the handle open the banjo slightly- if you see bubbles, keep the pressure on the handle untill the bubbels stop- while pressing the handle, tighten the banjo fully.

Good luck!

[B4ndit]

Haakon

Haven't done the flush yet. but your answer starts to make sense. My only question is. Why remove the reservoir covers then cover them with something. Why just not leave the covers on.

[Haakon]

Maybe you can leave the covers on?
When you do a ABS flush a "geysir" of fluid/ air shoot up from the pump (front) and reservoir (rear)
To remove the lids are what BMW describe when a new ABS-N unit have been replaced.
New ABS-N units are filled with air, not brake fluid.
Its just how I do it- so....? 
IF it must be done that way I can not say for sure
OK?
Haakon

PS: guess your bike have  Integral ABS, not ABS-N?

[B4ndit]

Its a 2011 GS. Reprom doesn't mention flushing ABS. So GS 911 seems to be the able to do it.

[Jughead]

For what it's worth, my 2c ...

The 2011 ABS does NOT retain any fluid in the pump like the Servo assisted pumps do.

When bleeding the brakes, fluid is pumped from the master cylinder (on the handlebar for the front and at the brake pedal for the rear) directly and straight through the ABS pump to the slave cylinders on the wheels.  There is no place in the pump where fluid remains stagnant.

All the ABS bleed test function does is shuttle the valves inside the pump to ensure that no air is trapped in them.

On the older Servo pumps there are 2 reservoirs inside the pump, one for the front, one for the rear.  ie  On servo assisted bikes you have 4 reservoirs in total.  These are the pumps that need to be flushed.

WRT flushing the fluid, mine gets done every 10 000km or annually.  The exception to this is if I have have a brake fade, the fluid then gets replaced ASAP after the fade.  Since the fade is caused by the fluid boiling, its integrity had been compromised and imho needs replacing.
 
Brake fluid is one of those life and death things and at ZAR32/flush ...

[B4ndit]

Now gone through this process. Took 500 ml of brake fluid in total and a good hour of my life.

Firstly I bled all brakes as usual. Then I put the caps back on the reservoirs.

The used the GS 911 to flush the ABS.

Then once again bled all the brakes in the usual manner.

Brakes are rather good now.

[Haakon]

In a earlier posting I told to have both reservoir covers OFF.
I guess that is only when you flush a newly installed "MRAABSN" (ABS-N)
A lot of air trapped inside the ABS has to be "released" and may blow the reservoir lid off 
Haakon

[Beemerboy]

@ Jughead,

You could concider using DOT 5.1 ( NOT DOT 5 !) brakefluid.

DOT 5.1    
Dry  boiling point: 260 °C (500 °F)    
Wet boiling point: 180 °C (356 °F)

as DOT 4
Dry  boiling point: 230 °C (446 °F)
Wet boiling point: 155 °C (311 °F)

Both DOT 4 and DOT 5.1 are polyethylene glycol-based fluids

greetz 

[Haakon]

What "safe to use" brake fluid does NOT attract water?
If any???
Many years ago I decided to change my brake fluid once a year, just to make sure its "dry" (not water contaminated)
Too many times have I had total brake failure caused by water contaminated brake fluid.

[Jughead]

@ Jughead,

You could concider using DOT 5.1 ( NOT DOT 5 !) brakefluid.

DOT 5.1    
Dry  boiling point: 260 °C (500 °F)    
Wet boiling point: 180 °C (356 °F)

as DOT 4
Dry  boiling point: 230 °C (446 °F)
Wet boiling point: 155 °C (311 °F)

Both DOT 4 and DOT 5.1 are polyethylene glycol-based fluids

greetz 

Correct! 5.1 is all I use.

However, ride some steep passes downhill and the fluid (especially on the rear) will quickly exceed even the 280deg mark.