Results 1 to 23 of 23
  1. #1
    mtbr member
    Reputation: farenj's Avatar
    Join Date
    Jan 2010
    Posts
    43

    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"
    Reputation: Warp's Avatar
    Join Date
    May 2004
    Posts
    18,780
    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.
    Check my Site

  3. #3
    On your left.
    Reputation:
    Join Date
    Jan 2004
    Posts
    1,177
    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
    mtbr member
    Reputation: farenj's Avatar
    Join Date
    Jan 2010
    Posts
    43
    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"
    Reputation: Warp's Avatar
    Join Date
    May 2004
    Posts
    18,780
    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.
    Check my Site

  6. #6
    mtbr member
    Reputation: farenj's Avatar
    Join Date
    Jan 2010
    Posts
    43
    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
    mtbr member
    Reputation: farenj's Avatar
    Join Date
    Jan 2010
    Posts
    43
    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"
    Reputation: Warp's Avatar
    Join Date
    May 2004
    Posts
    18,780
    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.
    Check my Site

  9. #9
    mtbr member
    Reputation: knl2stl's Avatar
    Join Date
    Jan 2011
    Posts
    222
    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
    mtbr member
    Reputation:
    Join Date
    Mar 2008
    Posts
    662
    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
    mtbr member
    Reputation: farenj's Avatar
    Join Date
    Jan 2010
    Posts
    43

    ... 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
    mtbr member
    Reputation:
    Join Date
    Mar 2008
    Posts
    662
    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
    mtbr member
    Reputation:
    Join Date
    Nov 2007
    Posts
    746
    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
    mtbr member
    Reputation: farenj's Avatar
    Join Date
    Jan 2010
    Posts
    43
    pwu_1,

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

  15. #15
    mtbr member
    Reputation:
    Join Date
    Oct 2007
    Posts
    9
    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
    RIDE...
    Reputation: MarcoL's Avatar
    Join Date
    Jun 2007
    Posts
    417
    Thanks it worked great

    Sent from my Nexus 7 using Tapatalk 2

  17. #17
    mtbr member
    Reputation: farenj's Avatar
    Join Date
    Jan 2010
    Posts
    43
    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
    Reputation:
    Join Date
    Jun 2004
    Posts
    247
    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
    mtbr member
    Reputation: ktm520's Avatar
    Join Date
    Apr 2004
    Posts
    1,422
    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
    Reputation:
    Join Date
    Jun 2004
    Posts
    247
    Nice job KTM520.

    Thanks for the thread and support gents!

    Let me know if I can help with anything.
    Jude

  21. #21
    mtbr member
    Reputation: 006_007's Avatar
    Join Date
    Jan 2004
    Posts
    8,445
    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.......

  22. #22
    mtbr member
    Reputation:
    Join Date
    Apr 2014
    Posts
    7
    I got the same problem on my MT2 (lever were touching the bar) in order to solve them I had to apply these corrections:

    Remove the air bubbles using the process described in the file "Quick_bleed_instruction_final_techtip_2_May_2012_ 01.pdf". On the final part I had to try to fill the system with as much oil as possible (a little bit of overfilling.
    Problem of loose tank described in "http://www.support-english.magura.com/index.php?showtopic=5053". The tank of the master cylinder is just between the bar and the main plastic part of master cylinder. Sometimes it gets loose: remove the 2 Torx Bolts: threaded studs will appear. Use a plastic tape and pliers to screw those studs without damaging the threads.
    I still believe these are good brakes they worked well

  23. #23
    Magura N. America Svc Mgr
    Reputation:
    Join Date
    Jun 2004
    Posts
    247
    Hi, You can save the MC by performing the above repair with little hassle. In fact, I lock two 5mm nuts together on the steel stud of the MC and then turn both locked nuts AND the steel stud to tighten the top cap located between the MC and the handlebar.

    As for pulling the lever blade to the handlebar, make certain your pads are not contaminated from all the service and bleeding on the brake because it is real easy to have residual bleed fluid find its way down into the pad area of the caliper!

    It doesn't take much and heat helps it find its way to the pads and or rotor!

    This will cause all friction to go away and even though the pad contact/lever engagement is good, no friction allows the lever blade and all its componentry to flex enough and deceive you into thinking another bleed is in order.

    Good luck and let me know what you need and we will get you back up and on the trail.
    Jude

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  

Can't find it? Just search our site!