DIY Brake Fluid Change and the ABS Unit?

[1050rat]

Greetings peeps,

My first techical forum post so please be gentle with me ;-)

Can anyone tell me if there are any special requirements to change the brake fluid on my 2014 R1200GS. My concern centers around the ABS unit and making sure any fluid in there is properly flushed and changed as well and that there is no air in the system on completion.

I spoke to dealer yesterday who said it "should" be OK to do a conventional bleed on the brakes that the ABS issue was only a problem on the older air cooled models?

The workshop manual only talks about a conventional bleed using vacuum extraction and doesn't mention any special requirements for flushing of the ABS unit anywhere I could see. I will be using an old fashioned hose with plastic jug on the end and pumping the lever!

What has confused me a little is a video on YT using the 911GS unit (£400 or thereby) which shows a procedure for flushing of the ABS unit using it and re-bleeding the brakes thereafter.

If anyone can clarify the situation that would be greatly appreciated.

Cheers

1050rat

 

[Deleted account 191119001]

Have a read of this, little bit cheaper

http://advrider.com/index.php?threa...r-bmw-motorrad-the-1000-word-edition.1130770/

 

[Deleted account 181015001]

I have done a few bikes with ABS and many without I just pump the fresh fluid through making sure the reservoir is never allowed to run dry, putting plenty through until the system is well flushed out.

 

[Dermot.B]

I too was confused by that video. However I bled the brakes as you would normally ie pump up the pressure(lever front calipers pedal rear caliper) crack open the bleed nipple with tube attached and feed into a suitable container, when the lever has reached the end of its travel close the nipple and pump up the pressure again, continue until you are getting the new clear dot 4 coming from each nipple (two front one rear) I ran approximately 400ml through the system. Far easier job than the previous airheads which did involve bleeding the ABS unit separately as there is a reservoir and bleed nipples for each system in the unit. I stand to be corrected but this is the procedure I followed.

Sent from my A0001 using Tapatalk

 

[Andi_archer]

I did see a tip I have not used yet of using a rubber hose with the end sealed and a small slit in the side near the bottom to aid bleeding.The rubber hose hangs from the Caliper into your chosen receptacle the slit sealing on releasing the brake handle thus preventing air getting into the system.

 

[Dermot.B]

Ha, They used to sell something similar years ago (two shillings and sixpence!) calling it a self bleeder, it works fine too.

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[beaver]

just as normal.. 2nd page down the bottom... Just pump it through as before, watching not to get air in

http://www.ukgser.com/forums/showthread.php/480007-Rear-brake-pedal-goes-down-too-far-bleeding/page2

 

[Deleted account 191119001]

Ha, They used to sell something similar years ago (two shillings and sixpence!) calling it a self bleeder, it works fine too.

Sent from my A0001 using Tapatalk

Got something like that brand new in the toolbox from my old Bonneville that had no ABS

 

[1050rat]

OK. I went ahead and bled the brakes conventional stylee fronts no problem but the rear was a disaster. I now have no rear brake to speak of after also trying to reverse bleed it. Some time after I started the reverse bleed I noticed fluid weeping from somewhere around the reservoir down onto the ground. There was no sign of the reservoir filling up as it should during this procedure as it all kept weeping out before it got to the reservoir. This to me suggests the reason we experience spongy rears as air is escaping / entering? somewhere around the reservoir but I couldn't see exactly where. These systems are supposed to be airtight right?

Looks like I am going to have to contact my dealer to sort this I can't find much online except a lot of complaints about it. Anyone know of a technical bulletin, fix with aftermarket parts or the like?

Cheers

 

[Dermot.B]

Forget about reverse bleeding fill the reservoir pump the brake pedal and crack open the bleed valve until the pedal sinks close nipple and repeat until you get a good pedal.

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[1050rat]

Forget about reverse bleeding fill the reservoir pump the brake pedal and crack open the bleed valve until the pedal sinks close nipple and repeat until you get a good pedal.

Sent from my A0001 using Tapatalk

Ta sorted!

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[Dermot.B]

Good stuff.

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[colinshotts]

2017 R1200GS 14k miles
I ride all winter in Scotland so salt takes its toll. I messed up while cleaning front caliper pistons a few weeks ago. I was hand cramp pushing them in then using brake lever to pump them out repeatedly to free them all up BUT I didn't open bleed nipple during this operation. I've now lost my nice firm brake (lever travels at least a third before brake applies, previously it was very small amount of travel, which I like and I'm used to) and no amount of bleeding will cure it. I've bled using the traditional pump into a bottle method, open/close nipple on every pump method and even used a Mityvac hand vacpump and in total have used over 1.5 litres of fluid!
My mate reckons because of the forcing of the pistons back in with nowhere for the pressure to go it could have done something to the master cylinder seal. Any opinions on that?
OR any suggestions as to what is going on here? Is it the mystery of the ABS unit?
Another little side that's annoying me- when the lid is off the reservoir during bleeding when I pump the lever there's a little spurt comes up from the fluid, like a little geyser type thing, if lever pulled in quite fast it can spurt enough to go out over edge of reservoir! This is something I've NEVER seen on bikes- is it normal for the brakes on the GS LC? certainly didn't occur on the air cooled GS.
Sorry about the rant but I wanted to fully explain my pain.

 

[Warlord]

I DIY my own servicing, but leave the brake fluid changes to the BMW Dealer.

Cost me £60 front and rear fluid change, which is acceptable considering liability and hassle you could have.

 

[Alan R]

2017 R1200GS 14k miles
I ride all winter in Scotland so salt takes its toll. I messed up while cleaning front caliper pistons a few weeks ago. I was hand cramp pushing them in then using brake lever to pump them out repeatedly to free them all up BUT I didn't open bleed nipple during this operation. I've now lost my nice firm brake (lever travels at least a third before brake applies, previously it was very small amount of travel, which I like and I'm used to) and no amount of bleeding will cure it. I've bled using the traditional pump into a bottle method, open/close nipple on every pump method and even used a Mityvac hand vacpump and in total have used over 1.5 litres of fluid!
My mate reckons because of the forcing of the pistons back in with nowhere for the pressure to go it could have done something to the master cylinder seal. Any opinions on that?
OR any suggestions as to what is going on here? Is it the mystery of the ABS unit?
Another little side that's annoying me- when the lid is off the reservoir during bleeding when I pump the lever there's a little spurt comes up from the fluid, like a little geyser type thing, if lever pulled in quite fast it can spurt enough to go out over edge of reservoir! This is something I've NEVER seen on bikes- is it normal for the brakes on the GS LC? certainly didn't occur on the air cooled GS.
Sorry about the rant but I wanted to fully explain my pain.

Given that the hoses are not ruptured, in my experience lack of lever pressure tends to be a result of pushing against air which compresses and absorbs the pressure so that when you release the lever it expands and prevents new fluid entering the system;

pushing against something like a piston seal or dust seal which has stuck through damage or dirt and is not allowing the piston to slide forward fully against the brake pad - again on release of the lever the piston moves back by the torsion force of the seal rubber maintaining the feeling of sponginess in the system;

or, not pushing at all because the master cylinder seal is allowing fluid to leak around it because it it worn or ruptured.

Given that you say that you do eventually feel pressure, my money would not be on the master cylinder being at fault. The little squirt of fluid as the master cylinder piston passes the reservoir hole is normal - don’t squeeze too fast when the reservoir lid is off! It also indicates that the piston is pushing fluid as required.

In older systems it is fairly common for the shiny sliding surface of the calliper pistons to become corroded as they gradually creep out and are exposed as the pads wear. Along comes the mechanic who, charged with replacing the pads against a time schedule, pushes them back in, introducing the roughened/dirty/corroded piston sliding surfaces to the rubber dust and pressure seals. The result - jammed pistons.

Newer systems seem to have pistons made of synthetic material that doesn’t corrode, but the same problem can occur if not cleaned properly before pushing them back when replacing pads. Remember, where the pistons work is a hostile environment contaminated with brake dust, road grit, rain, salt etc.
I clean my calipers each time I replace my tyres, using brake cleaner and an old tooth brush and wiping the dust seals with red rubber grease on a q-tip. The result is pistons that can be pushed home easily with thumb pressure. Also, my understanding of the system is that the fluid in the hoses moves easily without obstruction back into the reservoir when the pistons are pressed home. This has to be the case to prevent hydraulic lock when the lever is released.
My ramblings based on my experience. Hope this helps.
Alan R

 

[knutk]

The ABS brake system has lots of bends and kinks in the tubing. If a bubble of air is stuck in one of the bends regular bleeding will not be able to vent the air out, as the bubble moves a little bit for every stroke with the handle, but then the bubble returns to it's position when the pumping stops. A bleeder driven by a compressor ensures a continuous flow and will be able to remove all the air in the system.

As for the squirt in the reservoir: put a clean coin or any small metal plate into the reservoir that covers the hole. I prefer a magnetic plate as I may use a magnet on a stick to remove it.

my 2c

 

[colinshotts]

The ABS brake system has lots of bends and kinks in the tubing. If a bubble of air is stuck in one of the bends regular bleeding will not be able to vent the air out, as the bubble moves a little bit for every stroke with the handle, but then the bubble returns to it's position when the pumping stops. A bleeder driven by a compressor ensures a continuous flow and will be able to remove all the air in the system.

As for the squirt in the reservoir: put a clean coin or any small metal plate into the reservoir that covers the hole. I prefer a magnetic plate as I may use a magnet on a stick to remove it.

my 2c

Thanks for your 2c worth. I don't have a bleeder driven by a compressor (although I do have a compressor so you've got me thinking) but I did use a Mityvac hand vacuum pump. Do you reckon I just need to persevere with this?

 

[Alan R]

Thanks for your 2c worth. I don't have a bleeder driven by a compressor (although I do have a compressor so you've got me thinking) but I did use a Mityvac hand vacuum pump. Do you reckon I just need to persevere with this?

The problem that I have found with a vacuum pump is that it has a tendency to draw air in around the threads of the bleed screw.
At first glance this makes one think that the operation is successful and the air is exiting the caliper, only for the realisation to dawn that the stream of bubbles is not diminishing. As air is less dense than brake fluid a vacuum will always draw in air if a leak is present: the screw thread of the loosened bleed screw provides enough of a leak to defeat a low volume vacuum pump.

The key to successfully bleeding a system by hand seems to me to be pushing through fluid quickly enough to defeat the tendency of bubbles to rise back to their original position when pressure/flow is paused as you close the bleed screw, release the lever, squeeze the lever, open the bleed screw, stop for a while as you top up the reservoir etc.
A good but expensive solution are speed bleeders which are installed in place of the original bleed screws and incorporate a spring loaded ball bearing. This enables one to push fluid through without interruption quite quickly just using the brake lever.
A similar effect is obtained using the original bleed screws fitted with length of tubing that is blocked off at the remote end. The tube should have a 10mm longitudinal slit near the blocked end to act as a non return valve: it will allow fluid to pass during a lever pressure stroke but will prevent air entering on the lever return stroke.
I reckon that I can push through about 4x volume of the reservoir in about 5 minutes non stop using this tube (one needs an assistant to keep the reservoir topped up which also subdues the spurt back on the lever stroke).
Again, a rambling post, one based on experience - some of which was disastrous and frustrating but now mainly successful.
Alan R

 

[Skid06]

i thought you need a GS911 to bleed the Brakes, ABS Unit correctly?

 

[ShakeyGS]

I’ve recently changed the brake fluid on all circuits on my ‘16 LC.

I used a “self bleeder” tube on each nipple in turn. I removed the pads and then opening the bleed, retracted the pistons.
Using a syringe, I almost fully drained the master cylinder reservoir but never enough to let air in. I always feel more confident of a good result when the fluid travels the right direction through the system.

I did indeed use the GS911 to follow the ABS bleed procedure but this didn’t produce any bubbles at all.

I think I got my bleeder tube off eBay and it has a metal tube on trend whic contains a ball bearing, spring and grub screw to adjust the release pressure. Works very well IME.