Bleeding brakes

[Hexane12]

I have a late 2007GS. The brake system on the bikes allows them to be conventionally bleed using a piece of tubing, a bottle and the brake lever. Whilst using my GS 911 I notice there is a brake test facility which allows the ABS unit to flush the brake fluid from the module to the master cylinder. Do I use this option with my conventionally bled brakes?  I have bled the brakes successful in the past being unaware of this "Brake test" option.

[Haakon]

My personal view on this (many owners will not agree)
BMW service instructions say the ABS bleed function is just to be used if the ABS have been changed (or opened)
The spare ABS units come without fluid.
That said- if you do change the fluid it is for a reason.
The fluid is water contminated or just "too old".
IF the ABS have been in action that same old fluid will also be in the ABS unit.
I will say yes- if for no other reason, just to move the pumps and valves inside the ABS.
I change my fluid every year.
I first do a regular change- then do the ABS and last do another fluid change.
(To get rid of whatever fluid that was inside the ABS.
I have had vapour "lock" (right word?) and lost all braking action, very scary!
Haakon   

[StephanT]

I know of many BMW techs that don't do it... i.e. they do the conventional bleed only... that doesn't make it right though...

If you are pressed for time and it was just an annual flush, skip it (if you feel comfortable with your bleed and happy with the result)... however, I always do it... it's the correct procedure according to the motherland  ..and probably does not even take 5 minutes extra, for both circuits...

best,
Stephan

[malmac]

Hexane12

When you say you have a late 2077 model should I assume that it does NOT have the servo assisted brakes?

I have an early 2008 model and I am looking at how to best bleed the brakes so that the fluid in the ABS pump is correctly flushed with new fluid.


Thanks


Mal

[malmac]

For those of you who don't know and are looking for an answer - well trust me I am still in the dark too.

What have I learned, well bleeding the brakes is a most frustrating exercise and while I have tried;
1. normal bleeding
2. pushing the brake fluid from the nipple up - I made up a special nipple which doesn't leak, to do it
3. slight pressure bleed from the master cylinder down

I still feel like I have a pocket of air in the front brake lines.

For those of you who know about the GS911

Is there any way the GS911 model can be used in the brake bleeding process to flush air out of the ABS system?

Does anyone here know if the BMW laptop super brain system, actually does anything like actively participating in the bleeding process?

I have ridden the bike with the new ABS unit installed,

1. Took awhile for the new pads to bed in start releasing from the discs fully - seems to be 95% OK now
2. ABS light flashes when ignition is turned on (before it immediately went solid red
3. ABS initialises when I ride off, ABS light goes out
4. ABS works with back brakes activated to lock up - ABS light does not come on
5. ABS works with front brakes to lock up - ABS light does not come on
6. Ran GS911 - no error codes

So all in all that looks like mission accomplished - but I am told the BMW system needs to have the new ABS controller linked to the ECU or central brain or what ever. Does anyone actually know what that does?

Mal

[Haakon]

If you have a spongy brake feel you are NOT the first 
While pull LIGHTLY on the handle, carefully loosen the banjo bolt at the end of the front brake pump.
Have the handlebars all over to the left- so the brake pump is at its highest position.
(and have a rag under the banjo, to prevent brake fluid to damage your painted parts)
I am sure you will see small bubbles escape, tighten the banjo when the bubles stop.
Thats the first step.
---------------------
I understand you have fitted a ABS recently?
Did you do it yourself or did a BMW workshop do it?
When fitting a new ABS the ABS unit must be bled- using the GS911 ABS bleed procedure.
I believe you HAVE had that done already?
If so, and your ABS does work, it just a matter of trapped air, usually at that banjo bolt.
Haakon

[malmac]

If you have a spongy brake feel you are NOT the first 
While pull LIGHTLY on the handle, carefully loosen the banjo bolt at the end of the front brake pump.
Have the handlebars all over to the left- so the brake pump is at its highest position.
(and have a rag under the banjo, to prevent brake fluid to damage your painted parts)
I am sure you will see small bubbles escape, tighten the banjo when the bubles stop.
Thats the first step.
---------------------
I understand you have fitted a ABS recently?
Did you do it yourself or did a BMW workshop do it?
When fitting a new ABS the ABS unit must be bled- using the GS911 ABS bleed procedure.

Haakon

Thanks for the advice.
Will give that a try.

Mal
I believe you HAVE had that done already?
If so, and your ABS does work, it just a matter of trapped air, usually at that banjo bolt.
Haakon

[biker_bob]

If you have a spongy brake feel you are NOT the first 
While pull LIGHTLY on the handle, carefully loosen the banjo bolt at the end of the front brake pump.
Have the handlebars all over to the left- so the brake pump is at its highest position.
(and have a rag under the banjo, to prevent brake fluid to damage your painted parts)
I am sure you will see small bubbles escape, tighten the banjo when the bubles stop.
Thats the first step.
---------------------
I understand you have fitted a ABS recently?
Did you do it yourself or did a BMW workshop do it?
When fitting a new ABS the ABS unit must be bled- using the GS911 ABS bleed procedure.
I believe you HAVE had that done already?
If so, and your ABS does work, it just a matter of trapped air, usually at that banjo bolt.
Haakon

I've had my XCountry for 2 years now,  but have only just bought my GS9-11.
I've been reading this thread because I have the same question.
In a nutshell, what is the procedure for changing the ABS modulator?
I'm not scared of doing it, I've just never worked on an ABS bike before.

[malmac]

Hi Bob

I do not know exactly which ABS unit is used on your model, but I did finally get my ABS sorted out. In brief here is what I did.
1. bought a brand new unit
2. fitted the new unit - however I complicated the process by draining all the brake fluid from my system rather than leaving the system full by applying the brake, say front, letting out the pressure at the calliper, but instead of letting the brake lever off, just zip tie it to the handle bar so no more fluid comes down the line.
3. installed the new ABS unit
4. bled the brakes, which took me ages because I found it difficult to get all the air out of the system. I found applying the brakes, zip tie lever to hold pressure on and then I lay the bike over on its side on a large wooden block, over night to assist air to self bleed.
5. I then loaded a Beta version of the software for the R1200gs onto my laptop and ran through the bleed process for the ABS unit - this worked fantastically - I will now do this every year.
6. I now had good brake lever pressure - not spongy
7. I turned on ignition - the ABS light flashed - where as before it had immediately just stayed on solid (broken)
8. took the bike for a ride in the dirt, tried the rear brake to lock up - ABS functioned perfectly - ABS light did not come on to say I had a failure
9. feeling confident I applied the front brake to lock up - again ABS functioned perfectly
10. I returned home and ran the GS911 to see if I had any fault codes - none
11. I took the bike to my authorised dealer for a safety check - they ran the bike and used the full BMW computer check - no problems were found

Expensive, time consuming lesson - buy a GS911 and bleed your brakes properly every year or get your bike serviced by an authorised BMW workshop - because otherwise I think the ABS units will fail every four or five years.

Mal

[Haakon]

Bob, a very good description indeed
I am a bit confused tho, by securely (zip tie) the handle in the "brake applied" position you DO close off the brake fluid resevoir from the rest of the system.
Meaning: THAT IS the way to do it.
----------------
To remove the last sponginess- the handlebar banjo bolt must be bled too   
Haakon

PS- Do not only bleed the brake every year, make sure to change the fluid too.
At least every second year.
Vapor lock is NOT much fun- I know     

[biker_bob]

Thanks for the replies.
There was a complete braking system came up on Ebay for my bike, Front and rear mastercylinders, lines and ABS pump for £100. I asked the question about bleeding with the GS911 because most of what I'd read said that you can't bleed the system yourself. From reading the replies that I've seen here I've bought the brake system to keep as a spare, I reckon I can do this work myself.
When it comes to dismantling and storing the spare system, is it just a case of stripping everything down and cleaning all the fluid out?

I'm still not sure that I know exactly how the ABS pump works, from reading the procedure on this site it sounds like I need to set the pump running then pull the lever several times to circulate the fluid. So does the ABS pump pull fluid in from the braking system and circulate it round?

[malmac]

Bob


I don't know for sure, but if your ABS unit is the same as on the 2008 R1200gs models, when I activate the bleed process I can hear the electric motor on the ABS unit running. I know from disassembly of the old unit that that running the motor certainly must circulate brake fluid to some extent.

Mal

[Haakon]

The GS911 ABS bleed process start the ABS pump AND cycle the valves.

(From experiments with the new BMW diagnostic system I am a bit worried, it seems to JUST run the pump???  On the old ABS systems that will NOT bleed all of the system)