2011 XTR (M985) Brakes Leaking- Mtbr.com
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  1. #1
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    2011 XTR (M985) Brakes Leaking

    I bought the new M985 brakes a couple of months ago. They were feeling a little squishy, and when the bike is tipped upside down lever goes to the bar. So I decided to bleed them. No big deal, I've bled 100's of brakes before. Did the front one, fine. Started the rear one, and at the lever reservoir it started to leak when I bled it. The reservoir will not hold any fluid! It leaks out the black part (see pic). I have no idea whats going on, the bike has been sitting for a couple weeks, but was working fine before that. Any idea?
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  2. #2
    The Punk Hucker
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    Isn't that the "overfilled exhaust port". Not sure how it's called but I believe that when there is too much oil in the system, that's where the extra oil exits from.
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  3. #3
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    maybe! I'm gonna give shimano a call today
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  4. #4
    The Punk Hucker
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    Let me know, I could never get a confirmation this was indeed the overfill port.
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  5. #5
    Mudder
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    So I took it to my LBS and they are warrantying it. I'll keep ya posted.
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  6. #6
    The Cheater
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    DUDE! That's exactly the same problem I'm having right now with my rear brakes. I just came home from my LBS to see if they have a replacement set since I'll be selling mine. And I see quite a few posts of the same problem around the net. No, I never bled my brakes, these have been taken out on maybe 10 on road rides. Never had a problem with Shimano hydraulic brakes before and I've tried all that they released since 2009.
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  7. #7
    Mudder
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    They warrantied my rear lever and got it within a couple of days. But with these brakes I feel like you never can get the "pull" without overfilling the system to much (which makes it leak out of that hole). Plus the stopping power isn't great. I might get the new XT's. Way more power and no stupid hole for fluid to leak out of.
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  8. #8
    The Punk Hucker
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    Quote Originally Posted by slalomnorth65 View Post
    They warrantied my rear lever and got it within a couple of days. But with these brakes I feel like you never can get the "pull" without overfilling the system to much (which makes it leak out of that hole). Plus the stopping power isn't great. I might get the new XT's. Way more power and no stupid hole for fluid to leak out of.
    I hear you. I couldn't get the proper lever pull for my liking until I removed the wheel and got the piston out of it's seat until I got the proper lever feel. What I didn't do however is fill the system afterwards....
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  9. #9
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    2012 XTs also have there share of leakage issues. My 2012 XTs started leaking while I was bleeding also. I was starting to freak out and thought I might have to take them in for warranty. But I finished the bleed job (definitely wasn't leaking as much oil as you were), and surprisingly the leaking stopped after that. Though I realize these brakes are slightly different, my theory is that the reservoirs on these new Shimano brakes don't like the back pressure into the reservoir and causes the pressure relief port to let loose. Nor do they like any air in the reservoir, which seemed to help start a leak in the other lever I bled. I love these brakes now and they are working great.

  10. #10
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    Made a quick and easy fix in the local workshop.

    Found a matching bolt, put couple pieces of rubber rings made from old tube, and a washer on top of it. No leaking for half a year now

    2011 XTR (M985) Brakes Leaking-img_2831.jpg
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  11. #11
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    My XTR's are doing the same thing. I like that idea of putting a screw/bolt in there.

    Any idea of what thread pitch is needed to fit into that small port?

  12. #12
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    Quote Originally Posted by Gunnar-man View Post
    My XTR's are doing the same thing. I like that idea of putting a screw/bolt in there.

    Any idea of what thread pitch is needed to fit into that small port?
    Can't really tell. You will need to go through all available bolts to find the matching one. All i can say is that thread is pretty small. You can see it inside this port if look really close.
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  13. #13
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    Yeah I have tried all the small ones i have lying around and no luck so thought on the off chance someone knows, I can go to a bolt supply store and give the the exact specs.

    THanks anyways.

  14. #14
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    The correct fix is actually pretty easy and it doesn't involve running all over the place to find a small screw that fits the hole in the cap. I had this happen to me twice, the first time Shimano replaced the brake because they were only a few months old, then I had the same thing happen this spring when I was bleeding the brakes so I called Shimano and got a guys on the phone that knew exactly how to fix the issue correctly.

    There is a small rubber diaphragm that snaps over the the inside of the cap. If you bleed the brakes and end up getting too much fluid in the system the first few times you pull the lever good and hard the excessive pressure will force some of the fluid around the rubber diaphragm and you will then get the leakage out of the hole in the cap when you squeeze the brake lever. Along with that the leaver action feels like crap and isn't solid because the system no longer has enough oil.

    In order to fix the issue you need to take the brake lever off the bar, when you open up the clamp on the brake flip it all the way open and look for a small set screw down in the hinge area of the brake. That set screw is what holds the reservoir cap in place, remove the set screw completely and then thread it into the hole in the outside of the cap. You can then use your allen key in the set screw to gently wiggle the cap out of the reservoir. Pay attention to the direction of the rubber diaphragm as you pull the cap and diaphragm out as the diaphragm is about 1" long and fits up into the reservoir cavity, one side is flatted and needs to insert into the reservoir correctly. Anyway pull the cap/diaphragm out, pop the diaphragm off of the cap, clean all the oil out of the inside of the diaphragm, re-install it back on the cap and them put the whole thing back into the lever and then re-bleed your brake and you should be good to go.

    If you just bled your brakes prior to this issue occurring you should only need to re-bleed the the lever assembly without needing to go back through the entire process of bleeding the caliper.

  15. #15
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    Quote Originally Posted by Dr Wankel View Post
    The correct fix is actually pretty easy and it doesn't involve running all over the place to find a small screw that fits the hole in the cap. I had this happen to me twice, the first time Shimano replaced the brake because they were only a few months old, then I had the same thing happen this spring when I was bleeding the brakes so I called Shimano and got a guys on the phone that knew exactly how to fix the issue correctly.

    There is a small rubber diaphragm that snaps over the the inside of the cap. If you bleed the brakes and end up getting too much fluid in the system the first few times you pull the lever good and hard the excessive pressure will force some of the fluid around the rubber diaphragm and you will then get the leakage out of the hole in the cap when you squeeze the brake lever. Along with that the leaver action feels like crap and isn't solid because the system no longer has enough oil.

    In order to fix the issue you need to take the brake lever off the bar, when you open up the clamp on the brake flip it all the way open and look for a small set screw down in the hinge area of the brake. That set screw is what holds the reservoir cap in place, remove the set screw completely and then thread it into the hole in the outside of the cap. You can then use your allen key in the set screw to gently wiggle the cap out of the reservoir. Pay attention to the direction of the rubber diaphragm as you pull the cap and diaphragm out as the diaphragm is about 1" long and fits up into the reservoir cavity, one side is flatted and needs to insert into the reservoir correctly. Anyway pull the cap/diaphragm out, pop the diaphragm off of the cap, clean all the oil out of the inside of the diaphragm, re-install it back on the cap and them put the whole thing back into the lever and then re-bleed your brake and you should be good to go.

    If you just bled your brakes prior to this issue occurring you should only need to re-bleed the the lever assembly without needing to go back through the entire process of bleeding the caliper.

    Awesome. That worked perfect. Thanks boss.

  16. #16
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    Any way to avoid this from happening? Should the fluid be below the threads before replacing the reservoir?

  17. #17
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    If you bleed the brakes correctly using the bleed kit and cup you really shouldn't have this problem. I was trying to firm up the brake lever feel by getting a little bit more fluid into the system by applying pressure to the bleed syringe at the caliper when finishing my bleed. You can get more fluid into the system and firm up the lever but I've found that the diaphragm is very sensitive to over filling and it will pop and push fluid out of the reservoir cap.

    Now, when I bleed my brakes, in order to get as much fluid into the system as possible and give me the firmest lever, I back the pad contact screw all the way out and I adjust the lever reach so it is also all the way out before I start the bleed. After bleeding I then reset the pad contact screw and reset my lever and this seems to give me a good solid lever.

  18. #18
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    Dr Wankel: That's interesting what you say about the pad contact screw. Shimano recommends the opposite -- screwed all the way in.
    Do you find adjusting that screw for bleeding makes a difference?
    I know adjusting the lever all the way out definitely made a difference for me. Much firmer brake feel by doing that before bleeding.

  19. #19
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    Quote Originally Posted by jon123 View Post
    Dr Wankel: That's interesting what you say about the pad contact screw. Shimano recommends the opposite -- screwed all the way in.
    Do you find adjusting that screw for bleeding makes a difference?
    I know adjusting the lever all the way out definitely made a difference for me. Much firmer brake feel by doing that before bleeding.
    I really cant tell if it makes a difference at all, backing it all the way out prior to bleeding was a recommendation that one of the mechanics at my LBS had so I tried it. By my way of thinking if it screws into the reservoir cavity it must displace a small amount of fluid, which should allow you to get more into the the system if it is backed all the way out while bleeding but I'm not sure.

    That said, the feel and firmness of the lever improved considerably once I started adjusting the lever reach all the way out first prior to bleeding for me as well.

  20. #20
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    So why does the lever trick work? Isn't it just a reach adjust?

  21. #21
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    Quote Originally Posted by Dr Wankel View Post
    The correct fix is actually pretty easy and it doesn't involve running all over the place to find a small screw that fits the hole in the cap. I had this happen to me twice, the first time Shimano replaced the brake because they were only a few months old, then I had the same thing happen this spring when I was bleeding the brakes so I called Shimano and got a guys on the phone that knew exactly how to fix the issue correctly.

    There is a small rubber diaphragm that snaps over the the inside of the cap. If you bleed the brakes and end up getting too much fluid in the system the first few times you pull the lever good and hard the excessive pressure will force some of the fluid around the rubber diaphragm and you will then get the leakage out of the hole in the cap when you squeeze the brake lever. Along with that the leaver action feels like crap and isn't solid because the system no longer has enough oil.

    In order to fix the issue you need to take the brake lever off the bar, when you open up the clamp on the brake flip it all the way open and look for a small set screw down in the hinge area of the brake. That set screw is what holds the reservoir cap in place, remove the set screw completely and then thread it into the hole in the outside of the cap. You can then use your allen key in the set screw to gently wiggle the cap out of the reservoir. Pay attention to the direction of the rubber diaphragm as you pull the cap and diaphragm out as the diaphragm is about 1" long and fits up into the reservoir cavity, one side is flatted and needs to insert into the reservoir correctly. Anyway pull the cap/diaphragm out, pop the diaphragm off of the cap, clean all the oil out of the inside of the diaphragm, re-install it back on the cap and them put the whole thing back into the lever and then re-bleed your brake and you should be good to go.

    If you just bled your brakes prior to this issue occurring you should only need to re-bleed the the lever assembly without needing to go back through the entire process of bleeding the caliper.
    Do you recall if the flat side of the rubber diaphragm was towards the opening where you screw in the reservoir, or the opposite side? I think I put it back together with the flat side nearest the port and now I cant get fluid to push through from the caliper to the lever?
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  22. #22
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    I love you Dr Wankel

    Quote Originally Posted by Dr Wankel View Post
    The correct fix is actually pretty easy and it doesn't involve running all over the place to find a small screw that fits the hole in the cap. I had this happen to me twice, the first time Shimano replaced the brake because they were only a few months old, then I had the same thing happen this spring when I was bleeding the brakes so I called Shimano and got a guys on the phone that knew exactly how to fix the issue correctly.

    There is a small rubber diaphragm that snaps over the the inside of the cap. If you bleed the brakes and end up getting too much fluid in the system the first few times you pull the lever good and hard the excessive pressure will force some of the fluid around the rubber diaphragm and you will then get the leakage out of the hole in the cap when you squeeze the brake lever. Along with that the leaver action feels like crap and isn't solid because the system no longer has enough oil.

    In order to fix the issue you need to take the brake lever off the bar, when you open up the clamp on the brake flip it all the way open and look for a small set screw down in the hinge area of the brake. That set screw is what holds the reservoir cap in place, remove the set screw completely and then thread it into the hole in the outside of the cap. You can then use your allen key in the set screw to gently wiggle the cap out of the reservoir. Pay attention to the direction of the rubber diaphragm as you pull the cap and diaphragm out as the diaphragm is about 1" long and fits up into the reservoir cavity, one side is flatted and needs to insert into the reservoir correctly. Anyway pull the cap/diaphragm out, pop the diaphragm off of the cap, clean all the oil out of the inside of the diaphragm, re-install it back on the cap and them put the whole thing back into the lever and then re-bleed your brake and you should be good to go.

    If you just bled your brakes prior to this issue occurring you should only need to re-bleed the the lever assembly without needing to go back through the entire process of bleeding the caliper.
    Thanks mate - worked a treat!
    - Matt

  23. #23
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    Any chance someone knows about a similar solution for the m9000's? I have a lever that's behaving the same way (inconsistent lever feel, squirting / seeping from the overflow) but I can't find the set screw that's being referred to. If anyone has thoughts, I'm all ears. I've followed the shimano bleed procedure about as exactly as I can several times now.

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