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  1. #1
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    Magura MT6 brake problem : loss of pressure

    I have a problem with my Magura MT6 brakes: during a steep ascent (pushing/carrying) the point of pressure moves back (lever very close to grips), then during the downhill the point of pressure moves clearly forward again and the total power of the brakes (front or rear) is fully available. What could be the problem? I carefully bled the brakes several times but the trouble persists.

    Thanks for your help!

  2. #2
    "El Whatever"
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    The only plausible explanation is air in the master cylinder. That's the only part of the brake where the fluid could change position to allow that change respective to change in behaviour depending on inclination.
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  3. #3
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    Agree re air in line. Did you follow Jude Monica's YouTube video for bleeding - specifically pushing and pulling the fluid?

    Are you using magura rotors?
    M

  4. #4
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    I use Magura SL rotors (2037180mm).

    I agree the problem is air in the master cylinder. But the bleeding procedure (even Jude's) ignores one big problem with MT calliper : the seal between the brake calliper and the threaded nipple to insert for bleeding is weak. The original O-ring is easily crushed and let a bit of air enter the system. Even with a joint washer made of tube rubber I suspect air to leach the master cylinder.

    So what is the solution? Use a joint washer made of stiffer plastic?

  5. #5
    "El Whatever"
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    Quote Originally Posted by farenj View Post
    I use Magura SL rotors (2037180mm).

    I agree the problem is air in the master cylinder. But the bleeding procedure (even Jude's) ignores one big problem with MT calliper : the seal between the brake calliper and the threaded nipple to insert for bleeding is weak. The original O-ring is easily crushed and let a bit of air enter the system. Even with a joint washer made of tube rubber I suspect air to leach the master cylinder.

    So what is the solution? Use a joint washer made of stiffer plastic?
    You mean the EBT threaded plug? I have read some complaints about those getting easily damaged and that concerns me, as I just ordered a set of Magura MTS.

    Probably, it's designed with the specific purpose to get damaged before the carbotecture body it threads in. Anyway, it should be revised.
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  6. #6
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    No I mean the threaded nipple extending the syringe which is adjusted on the caliper at the place illustrated on the annexed picture.
    Attached Thumbnails Attached Thumbnails Magura MT6 brake problem : loss of pressure-mt6_caliper.jpg  


  7. #7
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    Maybe this screw (with an o-ring) is called EBT bleeding screw, I'm not sure about it.

    In any case the seal between the screw and the caliper is not guaranteed with the original o-ring...

  8. #8
    "El Whatever"
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    Quote Originally Posted by farenj View Post
    Maybe this screw (with an o-ring) is called EBT bleeding screw, I'm not sure about it.

    In any case the seal between the screw and the caliper is not guaranteed with the original o-ring...
    Oh, sorry... then please ignore what I said.

    The EBT is at the lever.

    You could use some suitable o-ring of buna or nitrile. Rubber is easily damaged by oil. Maybe even a slightly bigger o-ring.

    My old Louises use the same fittings for connecting the syringe and never had an issue with it.

    Close the master cylinder and before disconnecting the syringe at the caliper, activate the lever. If you have any air, you should see a bubble in the hose.
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  9. #9
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    How fast are you pulling the fluid back into the syringe at the caliper? My fitting does not have an o-ring. On my Marta SLs there is no issue if I pull the fluid back very very and extra very slowly.

  10. #10
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    i had good luck getting a good bleed doing this. At the end of the bleeding process remove syringe at the lever and before removing syringe at caliper pressurize it slightly, at that point i heard a bit of a hissing noise at the lever, not sure what that was but thats the only way i got a firm consistent lever

  11. #11
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    ... and if we just ... Finally a solution!

    After several prospects on foras I found the solution on the Magura forum (MAGURA Community): apparently the complex membrane circuit of the MT brake lever easily holds air even if the bleeding process is carrefuly done.

    Hereafter the suggestion of the Magura moderator:
    "Try the following: install pads in good condition or new and squeeze the lever blade several times and release it. Now turn the brake lever up slightly, about 20 degrees and undo the upper EBT screw. Half-fill a syringe with Royal Blood oil and place it into the EBT bleed opening. Pump out repeatedly with the syringe until you get resistance. Then press oil into the brake lever, repeat one or two times and again squeeze the lever blade. Thus you only bleed the brake lever, this is crucial because the standard bleeding procedure do not insure that air will not stay in the complicated membrane circuit of the brake lever. If air remains there the pressure point is not stable.

    This new procedure is a good remedy as long air stays at the top in the brake lever it has no effect if air stays in the brake calliper! Magura will publish this procedure soon.
    "

    Of course I tried this method AND IT WORKS!!! Some bubles came out on the first suction. Now the pressure point is stable and the power of my MT6s is perfect.

    So do not hesitate to complete a normal bleeding process with this easy trick!

    Good luck!

  12. #12
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    another trick if you want less lever travel is bleed with a few mm thinner block than the yellow one, maybe at the expense of some modulation but good for longer fingers

  13. #13
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    Quote Originally Posted by farenj View Post
    After several prospects on foras I found the solution on the Magura forum (MAGURA Community): apparently the complex membrane circuit of the MT brake lever easily holds air even if the bleeding process is carrefuly done.

    Hereafter the suggestion of the Magura moderator:
    "Try the following: install pads in good condition or new and squeeze the lever blade several times and release it. Now turn the brake lever up slightly, about 20 degrees and undo the upper EBT screw. Half-fill a syringe with Royal Blood oil and place it into the EBT bleed opening. Pump out repeatedly with the syringe until you get resistance. Then press oil into the brake lever, repeat one or two times and again squeeze the lever blade. Thus you only bleed the brake lever, this is crucial because the standard bleeding procedure do not insure that air will not stay in the complicated membrane circuit of the brake lever. If air remains there the pressure point is not stable.

    This new procedure is a good remedy as long air stays at the top in the brake lever it has no effect if air stays in the brake calliper! Magura will publish this procedure soon.
    "

    Of course I tried this method AND IT WORKS!!! Some bubles came out on the first suction. Now the pressure point is stable and the power of my MT6s is perfect.

    So do not hesitate to complete a normal bleeding process with this easy trick!

    Good luck!
    Let me see if I got this right.

    You are using the syringe with plunger installed and sucking up fluid(from a bottle of extra fluid) into the syringe until its half full, then you install syringe with plunger still installed into the EBT and you pull on the plunger to suck fluid/air out from the reservoir, then you push on the plunger and pump fluid back into the reservoir?

    That sound about right?

  14. #14
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    pwu_1,

    Your're right, this is exactly what Magura is about to officially advise!

  15. #15
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    Thanks for this thread, it saved me! I will say that you probably want to tilt the lever up to 45 degrees or so before removing the syringe to minimise the amount of lost pressure when you remove the syringe. Things get messy and it's also a good idea to have that EBT screw ready to go. Two sets of hands would be nice!

  16. #16
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    Thanks it worked great

    Sent from my Nexus 7 using Tapatalk 2

  17. #17
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    The procedure I described above is now officially recommanded by Magura and can be downloaded on their web site (look for "MT-Techtip - Quick bleed instruction").

    Since I bleeded the masters with this method my MT6s work perfectly!

  18. #18
    Magura N. America Svc Mgr
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    Congratulations on your success Farenj!

    In addition to the comments above, Don't use the o-ring on the fitting at the caliper, just thread on the M6 threaded bleed fitting minus the o-ring.
    Then at the MC, don't thread in anything into the EBT, just press in the syringe's nipple.

    Good luck and let me know if you are still having problems.
    Jude

  19. #19
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    Had a similar symptom with my front MT4. Was planning to do a full bleed before I stumbled upon this thread. The master cylinder bleed did the trick. Thanks Magura.

  20. #20
    Magura N. America Svc Mgr
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    Nice job KTM520.

    Thanks for the thread and support gents!

    Let me know if I can help with anything.
    Jude

  21. #21
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    Quote Originally Posted by judemonica View Post

    Let me know if I can help with anything.
    I really want my Magura Louise FR to stop working so I can justify switching them to a nice set of MT-8.......

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