How to get the air out of the rear brake hard line..

Discussion in 'GS Boxers' started by Dirt_Boy, Jan 9, 2013.

  1. Dirt_Boy

    Dirt_Boy Been here awhile

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    Hi Team, I've had to replace the hard rear brake line from the rear brake master cylinder to the ABS module because it was damaged in an accident. Now the reservoir is lower than the ABS unit, so our friend gravity won't be of help getting the fluid down the line.

    The hard line is empty, so lots of air. Would I have to pressurize the line via the master cylinder reservoir to get the air out? Any Ideas Cheers :D
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  2. def

    def Ginger th wonder dog

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    Apply vacuum at the rear caliper while filling the reservoir with DOT4.
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  3. Dirt_Boy

    Dirt_Boy Been here awhile

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    Ok Ive been on Airheads for 32 years so this ABS stuff is s bit new..... :huhI thought the master cylinder applied pressure to the ABS unit and then the ABS unit applied pressure to the caliper? Like the the unit sent it a signal to apply more pressure to the brakes? Thanks
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  4. def

    def Ginger th wonder dog

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    To fill your hard line, apply vacuum to the rear caliper. You may find it necessary to bleed the rear circuit on the ABS hydro unit as well.
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  5. Multiplicity

    Multiplicity Been here awhile

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    Install the line to the master and the ABS block, crack it loose at the ABS block and bleed the air at the line into the ABS block using the master to pressurize it.
    Then you can pressure bleed the rear brake caliper.
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  6. rdwalker

    rdwalker Long timer

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    Just to clarify: the OP's machine is an R1150GS, right? With power brakes/ABS?

    If so, in case it's not clear from Multiplicity's post: there are two separate circuits involved. Master-to-ABS is independent from ABS-to-caliper.

    You bleed each section separately. Brake reservoir for the caliper circuit is inside ABS module. That section is really easy to bleed, by the way, since the power pump does all the work.

    Here is the pictorial on how to bleed brakes on an R1150:
    http://www.advrider.com/forums/showthread.php?t=455142
    It may seem intimidating, but it really is a simple procedure.

    Good luck! Robert.
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  7. Dirt_Boy

    Dirt_Boy Been here awhile

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    Hi Robert Yes you are correct it is a ABS model. And I thought there may be two separate but working in conjunction circuts. :clap
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  8. rdwalker

    rdwalker Long timer

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    If you follow the pictorial I mentioned and the original Hall-of-Wisdom documents, you'll have no problem. By the way, I just checked and am having problems downloading the HoW documents: PDF error? If you have the same problem, PM me with your email address and I'll send you these files from my own archive.

    Both procedure descriptions are a bit anal, you do not have to go that crazy. I like the idea of multiple clear hoses, described in the thread - it's easier than moving one hose nipple-to-nipple. I also like the funnel with stopper; that's quite simple - and easier to make than the version with threaded cap. As a point of advice: Beemer Boneyard here in NJ sells these funnels pre-made, though it may be not shipping to Oz. On the other hand: I do not remove the calipers for the procedure - just shove a thin wooden shim between the pads and the rotor. It's less work; more importantly, I don't like the idea of the caliper dangling on the brake line while I am wrestling the bleed nipple.

    The whole bleeding procedure (all 4 circuits) should take you perhaps a couple of hours. Most time is spent on preparations and cleaning up. You should do it every 2 years anyway, that way you'll assure the health of your ABS modulator.

    I'll be doing this stuff myself in a few weeks - all my bikes are due this season.

    Good luck! Robert.
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  9. def

    def Ginger th wonder dog

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    Did I miss something? It is not clear to me which ABS system we're talking about.
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  10. slartidbartfast

    slartidbartfast Love those blue pipes

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    ABS does not necessarily mean power brakes. I'm not familiar with bleeding the power/servo ABS system (recognizable by the pump sound whenever you apply the brakes) but you would probably find it only on later models (2001 or 2002 onward I believe.)

    For the non-servo ABS system, normal bleeding (by pressing the pedal, opening then closing the bleed nipple, releasing the pedal, and repeating numerous times) should shift the air out of the line without too much trouble. If you want to use a vacuum system or reverse bleed (forcing fluid back up from the caliper - not advisable with ABS unless you know the caliper and lines are clean internally) they should work too, but I don't see the point.
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  11. Dirt_Boy

    Dirt_Boy Been here awhile

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    Thanks for all of the input. Now I have replaced the broken hard line from the rear brake master Cylinder and have managed to bleed it and get the air out. Now this bike has been in an accident and at the moment it has the ABS and Brake failure warning lights on. I have fired it up and now if you have a look at the pic

    [​IMG]

    The round thing looks like a starter motor on its side. So I'm not sure if this runs the power brakes but I apply the brakes should I be getting any kind of noise / vibration from this this to know its working? Cheers
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  12. def

    def Ginger th wonder dog

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    Your model does not have power brakes. Bleed your brake system per the previous instructions.
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  13. everycredit

    everycredit Been here awhile

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    I thought with servos, one should not apply vacuum pressure? The issue seems moot here, but I have servo-assisted ABS on my 1150GSAAdv.
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  14. JimVonBaden

    JimVonBaden "Cool" Aid!

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    With the servos you do not need vacuum to bleed them. The servo pressure will flow the fluid easily.

    The control circuits are cravity feed, so also require no vacuum.

    Jim :brow
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  15. everycredit

    everycredit Been here awhile

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    Jim,

    Right--but I think I was reading in one of the halls of wisdom documents that vacuum should not be used, not because it's not as convenient as using the servo pump, but it could damage the pump? Or maybe I was thinking about another bike?

    Thanks
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  16. JimVonBaden

    JimVonBaden "Cool" Aid!

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    I do not know if the HOW says that, but I would agree! Light vacuum is used regularly, but a heavy vacuum can damage the abs pump seals!

    Jim :brow
    #16