R1200S Brake Question

nicholsonj2252 · Post by **nicholsonj2252** » Fri Nov 27, 2015 8:59 pm

Just fitted new front and rear brake pads and also done a full brake fluid flush . All fine with rear but something strange with front . As per the BMW manual I set the pistons back in the caliper then bled the master cylinder , RH caliper then LH caliper . I then using the GS-911 did the brake bleed function to cycle the ABS valves . I then re-bled the whole system again . Brake lever is firm , with pads back in braking is good , however on applying the brake lever as if you were doing an emergency stop .i.e very hard I am getting a noise out of the feed and return brake lines to the ABS unit . Only makes the noise when pulling lever very hard . I ended up doing the whole bleed cycle over again another twice , no air bubbles coming out of calipers or master cylinder bleed nipples , but after pulling brake lever hard and getting the noise I do get a very tiny amount of bubbles and i mean the very tiniest amount coming out in the master cylinder reservoir . I have left the bike with the brake lever tie wrapped to the handlebar overnight to see if it is some trapped air but was wondering could the noise just be the abs valves as it only happens when i pull lever very hard ? Any thoughts welcomed . I have not noticed the noise previously but i do have the bike fully stripped at the moment - no tank , no fairing panels , no headlight or clocks so noise would be more easily heard at the moment

ted · Post by **ted** » Fri Nov 27, 2015 11:14 pm

ive not had ABS on a bike but the car ones definitely 'pulse' with an associated noise. I assume you are not actually trying the brakes on the road. so i would have thought the ABS wouldn't actually kick in unless the wheels were turning ie the ECU thought the bike is moving?

nicholsonj2252 · Post by **nicholsonj2252** » Sat Nov 28, 2015 7:08 am

ted wrote:ive not had ABS on a bike but the car ones definitely 'pulse' with an associated noise. I assume you are not actually trying the brakes on the road. so i would have thought the ABS wouldn't actually kick in unless the wheels were turning ie the ECU thought the bike is moving?

The bike is stationary with engine switched off but i had wondered if what i was hearing was the ABS valves moving under hydraulic pressure , if not I've clearly got air in system and will have to find a method to remove it . After having bled the linked "wizzy" brakes on my 2005 GS a number of times I thought the R1200S ones would be easy

Dog Tyred · Post by **Dog Tyred** » Sat Nov 28, 2015 10:08 am

Turn the engine on before you test the brakes. That way you won't hear the noise from the brakes.

Think you are overthinking this. Do the brakes work? If yes, leave alone and just ride the bike.

Simples

DT

nicholsonj2252 · Post by **nicholsonj2252** » Sat Nov 28, 2015 10:50 am

Dog Tyred wrote:Turn the engine on before you test the brakes. That way you won't hear the noise from the brakes.

Think you are overthinking this. Do the brakes work? If yes, leave alone and just ride the bike.

Simples

DT

All sorted , leaving the braking system overnight with the brake lever tied back to the handlebar must have allowed trapped air out as there is no noise now and all working fine . Thanks to all for input .

Droptarotter · Post by **Droptarotter** » Sat Nov 28, 2015 4:20 pm

The 12S does not need the GS911 hooked up to bleed the brakes. Just bleed them like a normal non ABS system.

Cheers

nicholsonj2252 · Post by **nicholsonj2252** » Sat Nov 28, 2015 4:45 pm

Droptarotter wrote:The 12S does not need the GS911 hooked up to bleed the brakes. Just bleed them like a normal non ABS system.

Cheers

If you want to cycle the fluid in the ABS unit and purge any air the GS-911 has to be used . I agree that you can just bleed conventionally and not do the ABS unit however i prefer to initiate the ABS so as to cycle it and to clear the air/old fluid

Droptarotter · Post by **Droptarotter** » Sat Nov 28, 2015 5:28 pm

That's interesting......because what I do on the 12S is attach my vacuum sucker to the calliper bleed nipple and suck out all the old brake fluid....refill the reservoir and bleed normally.

Seems like doing it that way takes all the fluid out of the system, but I guess it's possible for some to be left in the ABS unit??

I did the same bleed procedure to a buddy's RT.....and quickly discovered that the RT has a different ABS system than the 12S....as I could not get the system to bleed.....doh!! Plus I did not know about using the GS911 to cycle the system.........double doh!!

Cheers

dysondiver · Post by **dysondiver** » Sun Nov 29, 2015 11:55 am

ah ,,, im seeing another reason to have to buy a 911 ,,, mind you i would have thought that if the fluid ran clean it would have eliminated the air from the abs ,,, otherwise anyone that ever got air into a line from the master cylinder would have to either own a 911 or get the stealer to bleed the brakes , is that the case.

nicholsonj2252 · Post by **nicholsonj2252** » Sun Nov 29, 2015 6:15 pm

dysondiver wrote:ah ,,, im seeing another reason to have to buy a 911 ,,, mind you i would have thought that if the fluid ran clean it would have eliminated the air from the abs ,,, otherwise anyone that ever got air into a line from the master cylinder would have to either own a 911 or get the stealer to bleed the brakes , is that the case.

I can only guess it is air in the ABS valves but its only a guess . BMW do not state you have to do it unless a new ABS unit is fitted but as I have the GS-911 and I'm already doing the job the 5 minutes extra to do the procedure is no extra hassle

dysondiver · Post by **dysondiver** » Sun Nov 29, 2015 6:29 pm

fair comment