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RE: Mighty Vac & Brake Bleeding


Skywagon

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I change my brake fluid every year. on this particular bike - 2014 R1200RT LC. It's very conventional and really easy to do with one exception. I cant quite reach the bleed screw while working the levers. I'm curious if you have any experience with vacuum pumps and if you would recommend one. I've used speed bleeders before but had one break off on me on an R100RT while loosening. It was such a pain to cure I've not used them again. Right now I have to get the wife unit to come out and do the levers while I work the bleed screw. Guess how much she enjoys up/down - hold... So thinking about vacuum pump to be done by myself. I watched a couple of you tube videos and looks like small bubbles can enter the reservoir where the clear tube attaches to the bleed screw kind of giving a false signal of air in the system.

 

Your experiences and advice is appreciated as always. One trick I do on my own is putting a 20 lb weight on the rear pedal and slowly bleed the rear....the front though...I haven't figured out a trick.

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One trick I do on my own is putting a 20 lb weight on the rear pedal and slowly bleed the rear....the front though...I haven't figured out a trick.

 

Elastic bands?

 

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I change my brake fluid every year. on this particular bike - 2014 R1200RT LC. It's very conventional and really easy to do with one exception. I cant quite reach the bleed screw while working the levers. I'm curious if you have any experience with vacuum pumps and if you would recommend one. I've used speed bleeders before but had one break off on me on an R100RT while loosening. It was such a pain to cure I've not used them again. Right now I have to get the wife unit to come out and do the levers while I work the bleed screw. Guess how much she enjoys up/down - hold... So thinking about vacuum pump to be done by myself. I watched a couple of you tube videos and looks like small bubbles can enter the reservoir where the clear tube attaches to the bleed screw kind of giving a false signal of air in the system.

 

Your experiences and advice is appreciated as always. One trick I do on my own is putting a 20 lb weight on the rear pedal and slowly bleed the rear....the front though...I haven't figured out a trick.

 

Morning David

 

No need for a Mighty Vac or speed bleeder.

 

Just use a longer (clear or transparent) hose attached to the bleed screw then terminate that hose in a small bottle, have the hose go in through the top then run to the bottom of the catch container.

 

Then either pump some of the fluid through the system or start by adding a little brake fluid to that catch bottle to be just above the bottom of the hose end.

 

Now elevate that catch bottle to be just above the height of the bleed fitting.

 

The fluid in the catch bottle will act as a fluid check valve & allow full bleeding with the bleeder valve remaining open throughout the bleeding process (just close the bleeder valve after clean fluid comes out of the bleeder hose).

 

 

 

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While what you are doing works to a point the LC bikes need a GS 911 or the mothership computer to open the abs block. When using it you can work the ABS pump for as long as you want and shut it down and turn the bleed screw in.

 

I installed speed bleeders on my RT and that made it very easy. However remember there are three different size speed bleeders on the RT. Each caliper has a different size.

 

I am sure a mighty vac will work fine though.

 

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Do not do this in the first two weeks of February as the cost of the set up expense will be 2X.

 

> Two days ahead of the day you want to change brake fluids call 1-800-FLOWERS to deliver to SO 1 day ahead of the job.

> For the next 48 hours keep you lip zipped on any hot button issues otherwise the flowers will be to dig out of a hole and not for an hour of her time

> Day of the brake bleed job ask SO to sit on the bike in the cold garage and pump while you bleed. Works every time.

 

Joking aside, I was wondering if you do need the GS-911 to purge the brake system as fully as the dealer using the computer with the roundel on it? My warranty is about over and I will start doing the maintenance myself.

 

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Do not do this in the first two weeks of February as the cost of the set up expense will be 2X.

 

> Two days ahead of the day you want to change brake fluids call 1-800-FLOWERS to deliver to SO 1 day ahead of the job.

> For the next 48 hours keep you lip zipped on any hot button issues otherwise the flowers will be to dig out of a hole and not for an hour of her time

> Day of the brake bleed job ask SO to sit on the bike in the cold garage and pump while you bleed. Works every time.

 

Joking aside, I was wondering if you do need the GS-911 to purge the brake system as fully as the dealer using the computer with the roundel on it? My warranty is about over and I will start doing the maintenance myself.

Well If you go out and make the ABS work before and after the brake flush it should be fine.

 

Moving anything inside before the flush would just be good practice as if you never activated ABS there may be something heavy in there or more important moisture.

 

Working after the flush would move fresh fluid through the ABS block and by dilution should be fine.

 

That is the way I see it but I could/have been wrong before.

 

 

 

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Thanks DR I'll give that a try. I have a bag with a tube already in it I use to use to bleed my old whizzy brakes and module on 2005 R1150RT. As far as the comment on GS911 for ABS block, I don't understand. Everything I've read seems to indicate that isn't necessary...but I certainly don't know and don't have a 911. When you say activated the ABS block the old fashion way I don't understand. Can you elaborate please. I've bled these brakes every year since new in the old conventional way. Both front and back reservoirs due draw fluid. I do it until clean which is usually two full cylinders full. What is it I'm missing and do I have 4 year old brake fluid trapped somewhere?

 

Edited by Skywagon
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Thanks DR I'll give that a try. I have a bag with a tube already in it I use to use to bleed my old whizzy brakes and module on 2005 R1150RT. As far as the comment on GS911 for ABS block, I don't understand. Everything I've read seems to indicate that isn't necessary...but I certainly don't know and don't have a 911. When you say activated the ABS block the old fashion way I don't understand. Can you elaborate please. I've bled these brakes every year since new in the old conventional way. Both front and back reservoirs due draw fluid. I do it until clean which is usually two full cylinders full. What is it I'm missing and do I have 4 year old brake fluid trapped somewhere?

The BMW computer and the GS-911 activate the brakes and it is a service function of both computers. It open the ABS block and flushes fluid through all the ports.

 

My suggestion is to go out and activate the ABS by engaging the ABS. This will basically do the same thing as either computer opening the ports on the ABS block and forcing fluid through the ports.

 

It may seem overkill but ABS blocks are very expensive and I believe they need to be used to move fluid through them. How you accomplish that is probably not too important as long as you do. I think moisture is the enemy here not so much dirty brake fluid although I am sure dirty brake fluid is bad also.

 

Again I am not saying you should or should not do this. I happen to have a GS-911 and one of it's service functions is to bleed brakes. When you use that function your ABS is open and pushing fluid through it.

 

I remember my LT and having to manually doing the ABS block to bleed brakes and that was no fun at all. You had to open many ports in a certain sequence to bleed it's ABS unit and it was a big pain.

 

Like I said if you go out and engage ABS, then bleed, then engage again to move fresh fluid through the block to flush it you should be fine.

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...My suggestion is to go out and activate the ABS by engaging the ABS. This will basically do the same thing as either computer opening the ports on the ABS block and forcing fluid through the ports...

 

Awesome! My next door neighbor rides a Duc 916, so I can come buzzing up the street and do a panic stop in front of our houses W/O having the cops called. And if the guy 2 houses down calls the police, I'll just tell the LEO that I was told to do it because of something I read on the internet. That should get me out a a ticket. Actually I don't think there will be and issue as all my neighbors already know I'm the guy with friends who leave burnout marks in front of my house, so a panic stop is light weight tomfoolery around here. (Yes at 60 I still have motor head friends who are going on 18)

 

Kidding aside, it seems like a logical way to move fresh fluid around the brake system. I'll will likely just buy the GS-911 anyway for the ABS bleed and other functions.

 

And still do panic stops in front of my neighbors house, with the ABS disabled, just to get him to quit mowing the lawn and come out for a ride.

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Well seeing where you are from I would think you have some salt on the roads. That is a very easy and calm way to engage ABS.

 

I would think a cop would let you go if you explained what you were doing. If you are not speeding and you lock up your brakes I do not think you could get into any trouble.

 

As far as a GS-911 It is worth it weight in cost for sure. Especially if you are like me and your bike will never see a dealer.

 

I had to buy the 30 dollar cable to make mine work on my 17 GS as it now has a "normal" ODB plug instead of the round connector to meet the European designation. They do make a GS-911 that is strait ODB. Not sure how that works out if you have a 17 and a 15 BMW bike? I guess you would need a cable with the correct male/female plugs?

 

My GS was made in the 5th month of 17 so the 5th month of 18 I will be doing the brake flush.

 

I used speed bleeders and the bag they sell and it was no muss no fuss easy as heck. The bag Speed Bleeder sells is worth every penny.

 

I do know each caliper on the RT was a different size speed bleeder (3) and I have not investigated the GS yet.

 

 

 

Edited by LAF
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Kidding mostly, although I have always practiced panic stops. Was a couple times a season ritual on the pre ABS bikes I have owned? Trying to hit that line between howling tire's and skidding. Maybe only a few times on my ABS equipped bikes no that the computer handles that magic.

 

During the OEM warranty period I let the dealer do it. The shop I go to have long time techs on staff that I trust to touch my ride. My waranty is up this year and from that moment on, I will do all my own wrenching. I have a '15 RT so I'll only need one connector. My '71/5 has Fred Flintstone brakes...no computer needed, just a lot of grip strength exercises to get a noticeable deceleration

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  • 1 year later...

Hi all.

LAF, you have talked about flushing the ABS unit. As I look through my BMW manual I can't see any mention of running the ABS pump.

Can you shed some more light on this. I can see that it is a function that can be performed using the GS911. BUT, I can't see any mention of running that pump from the instructions given in the BMW Manual. (I could be wrong!)

Surely if you can bleed right from the master cylinder to the slave cylinder, you ARE flushing the ABS block?

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Speaking for myself on the RT and the Super Tenere, you MUST run the pump to even hope to get the fluid exchanged in parts of the pump. There are valves and passages in there that are only open when the pump functions. How big a deal that is, I cannot say. I have never seen dirty fluid come out after I flush the system....then do the abs procedure. The abs pump still failed on the Super Tenere.......

 

The truth is that it is probably a good thing to activate the abs once a month or so. The front abs is the tricky part!

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58 minutes ago, AndyS said:

Hi all.

LAF, you have talked about flushing the ABS unit. As I look through my BMW manual I can't see any mention of running the ABS pump.

Can you shed some more light on this. I can see that it is a function that can be performed using the GS911. BUT, I can't see any mention of running that pump from the instructions given in the BMW Manual. (I could be wrong!)

Surely if you can bleed right from the master cylinder to the slave cylinder, you ARE flushing the ABS block?

 

Morning Andy

 

On the new (non servo assist) BMW ABS brakes there is no real need to run the servo pump (front is an accumulator type system so doesn't even use a  servo pump, even for ABS make-up during an ABS event). Rear brake is a servo assist when using the front brake lever (or in an ABS event)  but only when the rear  pedal pressure is lower than the front braking pressure (for most light rear  braking, or key-off braking, the servo pump is not used & the rear ABS valve is open for straight through flow from rear master cylinder. Rear pump doesn't run at key-off, it does run at key-on with rear wheel moving & front brake applied but rear servo only applies rear brake  if the rear brake pedal pressure is below the front brake apply pressure.  

 

The new ABS system is a fast-valve system that pretty well operates with the valves open until the brake system sees an ABS event, or the rear brake  pressure (from front apply) is above the  rear brake pedal apply pressure . 

 

BMW manual doesn't call for anything more than a basic key-off manual bleed as that gets most of the old fluid out. (it does call for front & rear brake pad push back during the bleeding though). It does say no vacuum bleeding.

 

If a person is real anal-- after initial (normal) bleeding of the rear system they can turn the key on, then when spinning the rear wheel with a foot (or hand)  apply the front brake lever. This should cycle the rear servo pump & push the last couple of CC's of fluid out of the pump, then re-bleed the rear brake system manually again. Manual doesn't call for this but I usually do it mainly to verify rear servo operation & it does purge the last couple of CC's of fluid out of the rear pump. 

 

 

 

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Thanks for the replies. I asked the question really on behalf of those folk that don't have a GS911.

My personal take on this is that if you flush your brake fluid regularly, then the fluid dilution of the new clean fluid is so high that it will take care of any trapped volumes of contaminated stuff once the brakes are back in everyday use.

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I have never changed the fluid on my RT, but I need to do so soon.  I have a Mighty Vac (that I've used in the past) and recently got a GS-911 to do my own service on my 2016 RT.

 

I've never been a fan of the pump and hold method of bleeding brakes... too much work when the vac will just suck the clean fluid through the system right at the bleed nipple.  I didn't use it on my 2005 RT when I had it because of the mystical whizzy brakes module (which I did bleed on my own a couple of times without issue).

 

Is there any issue with using the Mighty Vac on the 2016 RT and then following that up with a cycling the ABS module using the GS-911?  Since I already have the tools, this seems like the easiest way to do it to me.

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23 minutes ago, alegerlotz said:

I have never changed the fluid on my RT, but I need to do so soon.  I have a Mighty Vac (that I've used in the past) and recently got a GS-911 to do my own service on my 2016 RT.

 

I've never been a fan of the pump and hold method of bleeding brakes... too much work when the vac will just suck the clean fluid through the system right at the bleed nipple.  I didn't use it on my 2005 RT when I had it because of the mystical whizzy brakes module (which I did bleed on my own a couple of times without issue).

 

Is there any issue with using the Mighty Vac on the 2016 RT and then following that up with a cycling the ABS module using the GS-911?  Since I already have the tools, this seems like the easiest way to do it to me.

 

 

Afternoon alegerlotz

 

 

The BMW dealer manual warns to not vacuum bleed & no mention of ABS cycling, before,  during, or after the bleeding.

 

No need to pump & HOLD, just use a clear hose from the bleed nipple into a bottle or jar with the hose going to the bottom of the container  ending just below brake fluid level in the container (water bottle works good here).

 

Then place the container just above the bleeder nipple level (that prevents air bubbles for entering at the bleed nipple threads).

 

Then just open the bleeder & pump away (no need to close bleeder or hold anything) -- the hose ending below the fluid level in the container acts as a simple check valve. 

 

Be sure to push front brake pads back into the caliper then use something to shim or hold them there for the bleeding process (at least it is recommended to do this).

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26 minutes ago, dirtrider said:

The BMW dealer manual warns to not vacuum bleed & no mention of ABS cycling, before,  during, or after the bleeding.

 

Good to know.  I'll do it the old fashioned way...

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On 1/30/2018 at 7:35 AM, LAF said:

While what you are doing works to a point the LC bikes need a GS 911 or the mothership computer to open the abs block. When using it you can work the ABS pump for as long as you want and shut it down and turn the bleed screw in.

 

I installed speed bleeders on my RT and that made it very easy. However remember there are three different size speed bleeders on the RT. Each caliper has a different size.

 

I am sure a mighty vac will work fine though.

 

+1 on the speed bleeders. Quick and easy.

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On 1/13/2020 at 1:16 PM, alegerlotz said:

 

Good to know.  I'll do it the old fashioned way...

I had always used the "old fashion way" of flushing via pumping through with the brake lever/pedal!  It's kinda funny that the BMW dealer manual " warns to not vacuum bleed ", since the wethead RT's RepROM gives instruction based on using vacuum bleeder!  Doesn't matter to me, since I don't use a vacuum bleeder anyway!  GS-911, or MotoScan ABS activation isn't required to do the brake flush, and those SpeedBleeders do make life very much easier!  Spend a couple bucks extra and get the stainless steel ones.  I had the regular painted ones on my prior '07 RT, and found that the painted surface doesn't last, then rusting started in!

 

BTW, I consider it fairly important to syringe out as much of the old fluid from the reservoir as possible, before refilling with fresh fluid, and then do the flush.  The reservoir is the only place where the fluid can absorb significant amount of moisture from the air, and so you will want to get rid of the heavily contaminated (old) fluid rather than flushing it through the brake circuit..  JVB got it dead on, in his video!

Brake Flush - Front.pdf

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15 minutes ago, PadG said:

I had always used the "old fashion way" of flushing via pumping through with the brake lever/pedal!  It's kinda funny that the BMW dealer manual " warns to not vacuum bleed ", since the wethead RT's RepROM gives instruction based on using vacuum bleeder!  Doesn't matter to me, since I don't use a vacuum bleeder anyway!  GS-911, or MotoScan ABS activation isn't required to do the brake flush, and those SpeedBleeders do make life very much easier!  Spend a couple bucks extra and get the stainless steel ones.  I had the regular painted ones on my prior '07 RT, and found that the painted surface doesn't last, then rusting started in!

 

BTW, I consider it fairly important to syringe out as much of the old fluid from the reservoir as possible, before refilling with fresh fluid, and then do the flush.  The reservoir is the only place where the fluid can absorb significant amount of moisture from the air, and so you will want to get rid of the heavily contaminated (old) fluid rather than flushing it through the brake circuit..  JVB got it dead on, in his video!

Brake Flush - Front.pdf 455.6 kB · 3 downloads

 

 

Morning PadG

 

Your RepRom sort of  covers it just not to a great extent--  

 

 

Bleeding.vacuum.JPG

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3 hours ago, PadG said:

I had always used the "old fashion way" of flushing via pumping through with the brake lever/pedal!  It's kinda funny that the BMW dealer manual " warns to not vacuum bleed ", since the wethead RT's RepROM gives instruction based on using vacuum bleeder!  Doesn't matter to me, since I don't use a vacuum bleeder anyway!  GS-911, or MotoScan ABS activation isn't required to do the brake flush, and those SpeedBleeders do make life very much easier!  Spend a couple bucks extra and get the stainless steel ones.  I had the regular painted ones on my prior '07 RT, and found that the painted surface doesn't last, then rusting started in!

 

BTW, I consider it fairly important to syringe out as much of the old fluid from the reservoir as possible, before refilling with fresh fluid, and then do the flush.  The reservoir is the only place where the fluid can absorb significant amount of moisture from the air, and so you will want to get rid of the heavily contaminated (old) fluid rather than flushing it through the brake circuit..  JVB got it dead on, in his video!

Brake Flush - Front.pdf 455.6 kB · 5 downloads

 

 

I ordered the speed bleeders a couple of days ago and opted for the Stainless ones when I saw that those were an option.  With shipping the whole thing came to $50... 

 

I live in Southern California and only ride in the rain if I get caught in it (which is once a year maybe since it hardly rains here).  I'm still sticking to the recommended every two years brake flush, but the amount of humidity that the brake fluid is subjected to here is significantly less than it was when I lived in the northeast with humid summers and condensation of cool nights and warm days during the spring/fall.

 

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When I have trouble bleeding brakes and seems I can't get a firm handle, I tie the brake handle down (and/or brake pedal) overnight, and it seems to firm up the handle almost every time.

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The dealers mother ship computer does in fact activate the ABS block on a brake flush.  Watched it myself.  The GS-911 does activate the ABS block and it vibrates air bubbles out of the block or that is the description.

 

I have always had a GS-911 so I have used it on the RT and now the GS.  I use speed bleeders and a IV bag and can do it in less then a hour.  5 bucks for a can of brake fluid and a hours time I am good to go.  I do mine once a year because it is so easy. 

 

I also change the FD fluid every oil and filter change.  And I check cams for wear and valve clearance every 6000 also.  I changed all 4 exhaust valve shims on the 12K and like to make sure all is well.  All four were super tight from new.  And while I am there I confirm cam timing and cam position sensor position.

 

I enjoy maintaining my bike and am not saying it is how you should keep yours.  However I do think a brake flush where the ABS block is opened while new fluid is pushed through is the best way to do it.

 

 

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21 hours ago, alegerlotz said:

 

 

I ordered the speed bleeders a couple of days ago and opted for the Stainless ones when I saw that those were an option.  With shipping the whole thing came to $50... 

 

I live in Southern California and only ride in the rain if I get caught in it (which is once a year maybe since it hardly rains here).  I'm still sticking to the recommended every two years brake flush, but the amount of humidity that the brake fluid is subjected to here is significantly less than it was when I lived in the northeast with humid summers and condensation of cool nights and warm days during the spring/fall.

 

I also stick to the 2 years as well, even though I know that the amount of contamination in the reservoir is most likely very light at that point.  Cheap enough, and easy enough to do every couple of years. 

 

You may have read what I had said in the other forum on the subject.  The contamination with moisture happens mainly just in the reservoir (there may be some, at molecular level, that permeates through the plastic tubing wall, but that depends on the type of plastic used).  DOT 4 brake fluid is hygroscopic, which means that it will latch onto any available water molecules in its vicinity, but not as strongly hygroscopic as, say, ethanol in our E10 gasoline.  How much water that the fluid can attract depends on: time; amount of moisture in the air; and the surface area that is exposed to the air.  That last one is quite important, since no exposure means no chance for the fluid to get at the moisture!  Look at our brake reservoir, and you will see  a rubber "membrane" that is floated on top of the fluid, to reduce the exposed surface area to virtually nothing!

 

What surprised me the most that generally, people doesn't seem to realize that mere water contamination of the fluid does NOT mean anything . . . . . unless the contamination makes its way, all the way to the slave cylinder where it can be exposed to high temperature from braking!  That's why you need to make sure that you flush thoroughly, and as I said before, syringe out the contaminated fluid in the reservoir and refill with fresh fluid before commencing with flushing.

 

Lee - the ABS activation isn't done by GS-911 (or MotoScan), the device merely triggers the built-in routine in our bike's computer.  I am fairly sure that the routine is there for the purpose of clearing all air pockets from the module when the module is first installed or replaced.  The active components within the module are pistons, with small gaps between piston body and the bore, and the tiny ring of air in front of the seal will be impossible to eliminate statically.  Pulsing the pistons, by activating the ABS rapidly, will help to push that ring of air out onto the mainstream and flushed.  Once that air is gone, you really don't need to go through that again, since it serves no real purpose.  DOT 4 fluid don't get old (see any use by date on the bottle?) and only degrades via contamination (at the reservoir) and high temperature (at the slave cylinder).

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Any DOT 4 will do. THe price difference between name and non-name brand fluids is negligible so I tend to get whatever the most expensive one I can get in a very small bottle. I mean, there's no sense in buying a quart-sized container as you're only going to need a few ounces to flush both systems.

 

Last time I did it I bought a bigger bottle and did one of my cars at the same time. This time I'll probably do my bike and my Durango.

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PadG water in a brake line can boil causing steam.   At least that is what I have always been told and is why I do my car and bike on a regular schedule. 

 

I just had asked HEX this question in a open forum as to what the GS-911 is activating, and I am pasting the info here.

 

" The object is always to 'dissolve' any air in the circuit into the fluid - at least, for long enough that the air can be carried out of the brake circuit by the waste fluid, instead of being trapped at the highest point in the regulator.

Generally, the way this is done is by:
1) Very rapidly pressurizing and de-pressurizing the relevant circuit to thoroughly mix the air and fluid, then
2) Giving the operator enough time to purge the air/fluid mix from the circuit before the air re-separates from the fluid."

 

I was aware it is a routine of the ECU but it has changed in the GS-911 program from my 2015 RT to my 2017.5 GS.  The sound and duration has changed.  Not sure if it is a function of the bike itself or the routine is just different from a RT to a GS.

 

At any rate I would never hesitate to flush my brakes either by hand or using the GS-911 as for the cost and time IMHO great bang for the buck.  

 

As far as break fluid getting old then why does the bottle tell you to not use the unused portion?  I know it is because it is Hygroscopy. Another quick search and quote

 

" Hygroscopic means to "absorb water." Therefore, because brake fluid is hygroscopic, it will tend to absorb water and moisture. ... It means that brake fluid flushing should be done every 30,000 miles or so to remove the moisture. If there is excess water in the brake fluid, it will lower the boiling point"

 

And if it does not get old why does what I put in last year get yellow tinted by the time I do it the next time?

yellow+brake+fluid.jpg

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Brake fluid darkens as it absorbs water as well, so that's an easy way to tell that it needs to be changed (even if it is not time according to the service interval).

 

Back in my car racing days, we used to alternate ATE Super Blue and normal ATE high temp fluid.  When you did the fluid change, it was very easy to tell that you were into the new fluid because it was the opposite color to what you were just using in the system.  I think that the blue brake fluid has been banned in the US since then, however.

 

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Would it work to bleed the brakes at the calipers, then ride to a gravel area to make the ABS function, then go back and bleed again?  The reason I ask is some folks may not have a GS-911 to activate the ABS during the flush/bleed process.  Just a thought.

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4 hours ago, wbw6cos said:

Would it work to bleed the brakes at the calipers, then ride to a gravel area to make the ABS function, then go back and bleed again?  The reason I ask is some folks may not have a GS-911 to activate the ABS during the flush/bleed process.  Just a thought.

 

I have a natural aversion to the idea of purposefully causing, or attempting to cause, the ABS to kick in. I don't know why, that's just me. Absent that inhibition, what you suggest sounds like a viable alternative. If I did that that, I'd bring my tools and such with me and bleed the brakes immediately, like right there. 

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8 hours ago, Pappy35 said:

 

I have a natural aversion to the idea of purposefully causing, or attempting to cause, the ABS to kick in. I don't know why, that's just me. Absent that inhibition, what you suggest sounds like a viable alternative. If I did that that, I'd bring my tools and such with me and bleed the brakes immediately, like right there. 

 

That would make sense.  Thanks.

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Lee - the water contaminant has to get to the high temperature first before it can boil!!!!  Otherwise you are absolutely correct.  If you will read what I wrote again, you will see that the water contamination is only at the reservoir, and cannot propagate much beyond that in several years, if at all.  The master cylinder will push a small amount (relatively speaking) of fluid from the bottom of the reservoir into the brake line, when you apply the brake, but that same amount will return into the reservoir when you release the brake.  The most contaminated brake fluid will be near the top of the reservoir. 

 

As for the response that you had gotten, isn't that exactly what I had described?  Once the air is gone from inside the module, you are done, period!  You won't get any new air into that area even if you try hard, short of draining the whole module.  BTW, if in normal brake flush, you ever see any bubbles come out, it will mean that you have been very careless in letting the reservoir empty out while flushing, or something is screwed up!  I have done as much, if not more, brake flush that you have (mostly on cars, because all of my bikes prior to the RTs had cables), and have never observed any bubbles coming out!

 

alegerlotz - the dark color in "old" brake fluid is NOT from the water absorption, but from fluid that had been exposed to high temperature, and carbonized!  Very easy to prove.  When you do your brake flush, at the caliper, you will observe that the fluid starting to come out of the circuit is the portion that is dark, and then the color lightened to the fresh fluid color, before the flush is even completed!  Now, where did I say the brake fluid is exposed to high temperature?  The slave cylinder is what pushes the pads against the rotor, and hence the high temperature that may be present when braking hard.  Again, because the fluid color does NOT change with water contamination, it is very important to syringe out the reservoir first, and make doubly sure that you do have fresh fluid coming out of the bleed nipple before you finish.

 

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The only reason I change my brake fluid yearly is simply corrosion. Don't want crud build up, or corrosion that causes seal leaks or piston sticking. 

 

Don't care a bit about water lowering the boiling point. Race cars and bikes get the calipers hot enough to boil the fluid, Terry won't be boiling the fluid!

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1 hour ago, PadG said:

<snip> and cannot propagate much beyond that in several years, if at all. 

 

I'm not a chemist, just a mechanical engineer, so I'm a bit fuzzy with the terminology here. If brake fluid is hydrophilic wouldn't the water molecules be drawn along in the fluid to maintain some kind of equilibrium state? Like if you put a couple of drops of food coloring in a tub of water that is not convecting (hence no bulk motion), wouldn't it, over time, diffuse into the water? This is how I imagine brake fluid gradually becomes contaminated with water over time. The presence of the water lowers the boiling point of the homogenous mixture of water/oil.

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3 minutes ago, realshelby said:

The only reason I change my brake fluid yearly is simply corrosion. Don't want crud build up, or corrosion that causes seal leaks or piston sticking. 

 

Don't care a bit about water lowering the boiling point. Race cars and bikes get the calipers hot enough to boil the fluid, Terry won't be boiling the fluid!

Yeah, I agree. I'll never boil my oil so corrosion is the thing most of us mere mortal riders have to contend with.

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27 minutes ago, Pappy35 said:

 

I'm not a chemist, just a mechanical engineer, so I'm a bit fuzzy with the terminology here. If brake fluid is hydrophilic wouldn't the water molecules be drawn along in the fluid to maintain some kind of equilibrium state? Like if you put a couple of drops of food coloring in a tub of water that is not convecting (hence no bulk motion), wouldn't it, over time, diffuse into the water? This is how I imagine brake fluid gradually becomes contaminated with water over time. The presence of the water lowers the boiling point of the homogenous mixture of water/oil.

 

 

Morning  Pappy35

 

Yes, that is how it works with Dot 3/or/4, at least according to the testing that we do where I work.  It isn't instantaneous but eventually the moisture content equals out throughout the entire system. 

 

Dot 4 brake fluid is hygroscopic so it will grab moisture from wherever it can get it so a 2% area will grab moisture from a 3% or 4%  area until is equals out (& so forth all the along the entire  braking circuits)

 

 

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6 minutes ago, realshelby said:

The only reason I change my brake fluid yearly is simply corrosion. Don't want crud build up, or corrosion that causes seal leaks or piston sticking. 

 

Don't care a bit about water lowering the boiling point. Race cars and bikes get the calipers hot enough to boil the fluid, Terry won't be boiling the fluid!

 

Morning Terry

 

As long as you ride at normal altitudes then it takes a lot  or long hard aggressive braking to boil brake fluid in a motorcycle.

 

(but)- The fluid boiling  problems can  start effecting the braking once you get up to higher altitudes (like Pikes Peak high).

 

Back, (years ago) when I was involved with trailer towing brake testing we used to have a Pikes Peak test & that was very/very difficult to complete  the testing schedules  without boiling the brake fluid due to the high altitude effect on the fluid's boiling point.  In fact we had to use a non OEM brake fluid to complete the testing for some iterations.   

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Well I see from the beginning of this thread it's time for my annual flush (my personal schedule).  Since the weather is crap here today seems like a good thing to do.

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That is true DR. Good to bring up the point about elevation. It does make a dramatic difference in the boiling point of brake fluid ( most any fluid I presume ).

Not a worry, changing my fluid every year is probably about 3 times as often as average! 

 

 

 

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2 hours ago, Pappy35 said:

Yeah, I agree. I'll never boil my oil so corrosion is the thing most of us mere mortal riders have to contend with.

 

Morning Pappy 

 

That is on point as  brake fluid has a number of anti-corrosion additives that help to prevent long term corrosion & etching. (can be especially harmful during long storage periods)  

 

One of the problems with Dot4 brake fluid is that it takes in moisture as it depletes the  the anti-corrosion additives so the fouled fluid in conjunction with the moisture & dissimilar metals in the braking system components turns the brake fluid into a battery. (it's that continuous current flow that does a lot of the damage)

 

That is one of the tests that I used to run on my older stored or seldom ridden motorcycles. (I just don't have enough time or effort to bleed the old bikes yearly).

 

So I would just use a voltmeter to judge the health of the brake fluid. (voltmeter on 2 volt DC scale & (+) lead in the fluid & (-) lead on the master cylinder reservoir (clean contact spot). The limit on Dot3/4 brake fluid as far as the damage range goes is above .3 volts but I would always service if I found .2 or more volts. (Google this if you need more info)

 

This procedure also works good on the BMW motorcycle systems if they have a one piece master cylinder/reservoir  but I am unsure how accurate it would be on the BMW urine-sample-jar reservoir bikes. 

 

 

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18 minutes ago, dirtrider said:

 

That is one of the tests that I used to run on my older stored or seldom ridden motorcycles. (I just don't have enough time or effort to bleed the old bikes yearly).

 

So I would just use a voltmeter to judge the health of the brake fluid. (voltmeter on 2 volt DC scale & (+) lead in the fluid & (-) lead on the master cylinder reservoir (clean contact spot). The limit on Dot3/4 brake fluid as far as the damage range goes is above .3 volts but I would always service if I found .2 or more volts. (Google this if you need more info)

 

 

 

Learn something new every day! Never heard of doing this. I have a couple cars that may, or may not, get a few hundred miles per year. I might try this to see what happens. Caring for all our everyday cars and motorcycles is plenty, if I could reduce that a little on the other stuff it would be good.

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4 hours ago, PadG said:

alegerlotz - the dark color in "old" brake fluid is NOT from the water absorption, but from fluid that had been exposed to high temperature, and carbonized!  Very easy to prove.  When you do your brake flush, at the caliper, you will observe that the fluid starting to come out of the circuit is the portion that is dark, and then the color lightened to the fresh fluid color, before the flush is even completed!  Now, where did I say the brake fluid is exposed to high temperature?  The slave cylinder is what pushes the pads against the rotor, and hence the high temperature that may be present when braking hard.  Again, because the fluid color does NOT change with water contamination, it is very important to syringe out the reservoir first, and make doubly sure that you do have fresh fluid coming out of the bleed nipple before you finish.

 

 

Pour some brake fluid into an open container and leave it out for a while.  Its going to get darker.

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4 hours ago, dirtrider said:

 

Morning Pappy 

 

<snip>

 

So I would just use a voltmeter to judge the health of the brake fluid. (voltmeter on 2 volt DC scale & (+) lead in the fluid & (-) lead on the master cylinder reservoir (clean contact spot). The limit on Dot3/4 brake fluid as far as the damage range goes is above .3 volts but I would always service if I found .2 or more volts. (Google this if you need more info)

<snip>

 

I have one of those brake fluid testers. I don't know how accurate they are but I inferred from it that there is some electrical property of the fluid that's measured.

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19 hours ago, Pappy35 said:

Yeah, I agree. I'll never boil my oil so corrosion is the thing most of us mere mortal riders have to contend with.

That is what I thought until I did some passes out West.  I had never experienced brake fade in my entire life unless I was bedding in new pads and rotors.  That seems to have gone by the wayside as I see no discussions on that ever. 

 

When we were out for 28 days and 7600 miles I experienced brake fade a few times.  We ran some very technical routes where it was so twisty both up hill and down hill I experienced brake fade.  Uphill because you needed to keep your speed up to carry you through the corners and then slow down to enter the next, rinse and repeat.  Same going down hill except gravity or inertia is working against you.

 

Now brake fade can be caused by a few things, friction fade, mechanical fade, or fluid fade.  I am pretty sure I experienced friction fade.

 

PadG yes I miss read what you had typed on how air is handled in the ABS block, or I should say how the GS-911 handles it.  I do not agree on your thoughts on brake fluid and when and why to change it but my yellow brake fluid should show you why I changed mine.  As always some people like chocolate and some like vanilla.  Differences keep the world from being boring.

 

I think it is one of the most important and overlooked maintenance item there is on motorcycles and cars.  DOT 4 cost nothing compared to other things we use on our maintenance list.

 

OP you can use a mighty vac guys been doing it for many years.  You can use the old fashion way off pump, pump, hold.  You can buy an IV bag from speed bleeder .com and with a loop in it you dont have to close the bleeder at all once the loop fills.  You can buy the speed bleeders to go with the IV bag, or some fish air line into a baby food jar like we did 25 years ago.

 

I think the real issue is to do it.  No matter how you go about it just get it done.  Like I say I do mine once a year and living here in PA it is very humid so it is what I do. 

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20 hours ago, Pappy35 said:

 

I'm not a chemist, just a mechanical engineer, so I'm a bit fuzzy with the terminology here. If brake fluid is hydrophilic wouldn't the water molecules be drawn along in the fluid to maintain some kind of equilibrium state? Like if you put a couple of drops of food coloring in a tub of water that is not convecting (hence no bulk motion), wouldn't it, over time, diffuse into the water? This is how I imagine brake fluid gradually becomes contaminated with water over time. The presence of the water lowers the boiling point of the homogenous mixture of water/oil.

Think of being hygroscopic as being highly attracted to water!  At the molecular level, the molecules of the fluid is bouncing around at random (since it's in a liquid state), and when one encounters a molecule of water, it will latch onto it, due to the attraction.  The stronger the attraction, the more water molecule it can hold onto, but that strength lessen with the increase in number of water molecule that it latches onto.  What that mean is that, if it happens to manage to latch onto 2 water molecules, then its neighbor will be able to steal one from it, and that is how the water molecules will propagate within the fluid.  The water doesn't react, chemically, with the fluid, but just being carried along by it.

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20 hours ago, realshelby said:

That is true DR. Good to bring up the point about elevation. It does make a dramatic difference in the boiling point of brake fluid ( most any fluid I presume ).

Not a worry, changing my fluid every year is probably about 3 times as often as average! 

 

 

 

Actually, the boiling point that one see quoted are usually the boiling point at atmospheric pressure.  OTOH, the pressure that the fluid in your brake circuit "sees" is the much higher pressure of the applied pressure applied by you when braking, which will correspond to much higher boiling point of the fluid.  So, elevation doesn't really have any effect on it at all, since it doesn't affect the internal brake circuit pressure!

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18 hours ago, alegerlotz said:

 

Pour some brake fluid into an open container and leave it out for a while.  Its going to get darker.

If you have actually done this, I will accept it!  :)

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Lee - absolutely no arguments about changing brake fluid every couple of years!  I had also mentioned that it is easy and cheap enough to do it, for potential safety sake.  My main point is to try to prove that the GS-911, or OBDLink/MotoScan activation of the ABS while doing the brake flush  is unnecessary.  Doesn't do any harms, otherwise I would have tried to convince you that many years ago, when I first mention this to you in the other forum!  ;)

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