Bleeding ABS On ST1300

Discussion in 'Road Warriors' started by spawnx66, May 23, 2009.

  1. spawnx66

    spawnx66 Been here awhile

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    I had the dealer do a complete bleed and replacement of the brake fluid. I’m still not happy with the performance of the rear brake. Using the rear brake alone, it is rather spongy with limited power and a fair amount of pedal movement. With the front brake engaged, the rear pedal feels firm. However, if you release the front brake, you can feel the pressure drop on the rear pedal. Something is amiss with the linked system. The bleed procedure is complicated. The dealer claimed that some dip in the rear pedal is “normal”. A search of the online forums doesn’t give any specific answers, just lots of griping about the bleed procedure, dragging brakes, etc. Front brakes remain excellent in terms of feel and power.<o:p></o:p>
    <o:p> </o:p>
    It’s not clear to me after reading the bleed procedure if I can simply try to bleed the pedal circuit that controls the rear pistons independent of all the other circuits, proportion valve, and other complicated shit Honda elected to stick on this bike. Any thoughts? :ear<o:p></o:p>
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  2. spawnx66

    spawnx66 Been here awhile

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    Anyone?
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  3. innominate

    innominate Adventurer

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  4. dduelin

    dduelin Be Thou My Vision, Oh Lord Of My Heart

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    Rear pedal dip is only normal if the secondary master cylinder circuit has air in it. To properly bleed the SMC circuit you have to remove the left front caliper and tilt the rear of the SMC at least 15 degrees up from horizontal. This is a long circuit with the delay valve and/or proportioning valve in it and you have to make sure to flush 1.5 to 2 complete rear master cylinder reservoirs through the SMC to get all the air out of it. It's my understanding one must follow the proper sequence of bleeders and can't bleed that one out of sequence. You should have a hard pedal especially after paying a dealer to flush the entire system.
    #4
  5. mrbreeze

    mrbreeze I keep blowing down the road

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    I don't see why anyone would want linked brakes....

    not much help but at least I bumped your thread!
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  6. spawnx66

    spawnx66 Been here awhile

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    Thanks for the bump! :D

    Here's an update, I bled the rear caliper yesterday. No obvious air bubbles, fluid looked good. It didn’t seem to make much difference.

    I might bleed the proportioning valve but here's a dumb question do I need a vacuum bleeder. The only reason I believe I need vacuum bleeder to properly bleed the proportioning valve because I have no way of easily “pumping” the system; e.g. a pedal or lever? Any thoughts?
    #6
  7. dduelin

    dduelin Be Thou My Vision, Oh Lord Of My Heart

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    You don't need a vacuum pump to bleed the proportioning valve because it is on the right side of the bike close enough to the brake pedal to pump the pedal while opening and closing the bleeder on the valve. However you need a vacuum pump or a helper to do the left front caliper because no one has arms long enough to do both at the same time. If you do not use the right sequence of bleeding and removing and tilting the LF caliper you are really just wasting your time though. The fluid in this circuit travels from the rear reservoir, the delay valve, the secondary master cylinder to the proportioning valve. If you aren't paying attention, the tilt down of the SMC means you will never purge it in place. But don't despair it is only two bolts that hold the LF caliper in place and a piece of string or a bungee cord will hold it tilted up enough to purge it.
    #7
  8. OTRA

    OTRA n00b

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    Google just took me to this old thread. Wondering how you ended up fixing your rear brake issue. I had exactly the same symptoms with mine. There have been many SMC failures around, but I have found very few people (1!) with the the one you had. Honda was not help on that for sure.
    #8
  9. dduelin

    dduelin Be Thou My Vision, Oh Lord Of My Heart

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    I told him how to fix his problem. It isn't a failure of the SMC nor the linked brake system, it is a failure to follow instructions when servicing the brakes.
    #9
  10. OTRA

    OTRA n00b

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    Did he confirm that the problem went away?

    .
    #10