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  1. #1
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    Bleeding/Adjusting pad contact point xtr m988

    Hi, I recently put a pair of these awesome brakes on my beloved bike and even paid someone to bleed them and lighten my wallet $50 for the priveledge. However, the rear brake has significantly longer free play before the pads engage and almost bottoms out on the bars so I have to back off the free play adjuster about 5mm or so to get it close to the front brake engagement point. The free play adjuster doesn't seem that great so I am wondering if this can be adjusted by bleeding and if so how? Bearing in mind I have never bled mtb brakes before but done plenty of cars etc.any pointers would be greatly appreciated.

  2. #2
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    Sounds like the guy you paid $50 should do the job over, and make sure it's done right.

  3. #3
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    After having to shorten the hoses twice (didn't measure right) I had to bleed the brakes.
    By using the gravity method like Shimano's advise, I wasn't pleased with the bleed.
    Still a 'juicy' feel and no clear contact point.

    Went to the local pharmacy, bought 2 'luer-lock' syringes, got an M5 hosebarb and some clear 6x4 mm polyurthanehose and 2 hoselocks.

    By putting the O-ring from the lever bleedsrew on the M5 hosebarb I got an airtight connection (set-up: barb with O-ring to 8cm hose to syringe)

    For the caliper I use the bleedscrew and attach the hose directly.

    Took out the pads, pushed back the pistons.
    Strangely the yellow spacer had lots of play, so a few layers of tape held the pistons back symmetricaly and imo avoid overfilling the system with oil...

    Took the calipers off, so the brake hoses hung straight down and than used the 'Avid' method by pushing oil back and forth several times, tapping caliper and the lines, changing lever position (like in Shimano manual).
    After I thought the bleed was ok, I used the syringes for 'compression and suction' and could still extract some tiny bubbles.
    It took several repeats before the oil was bubble-free.

    If I pull the lever now, I can hear the pads land on the disc and at the same time feel that contact point in the lever.
    Short throw also: about 1cm to contact @ the end of the lever plus ca. an extra 0,5 cm to lock the wheel, somewhat more for the rear due to the longer line's expansion(?).

    Some people might like longer leverthrows but I like crisp braking with an early contact point.

    Oh, and I also think that the contact point adjuster screw doesn't do much...
    Just ads more weight.

  4. #4
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    Weird, guessing the guy didn't do a good job with them, I'd concure and ask him to go at them again and make them right - it's what I'd do if I did the same job for someone and they weren't happy and I always tell people who I setup or do brake work for exactly that. FYI, I just got some XT 785's and had to shorten both hoses, did it carefully and didn't have to bleed either and both have a nice hard feel to them, bite point adjuster works fine and very noticeable - I like my levers to stay far away from the bar when pulled for my big mits, so it's dialed all the way in.
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  5. #5
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    It ain't rocket science.
    Takes just some surfing on the net to learn the 'how to' and begin with it.

  6. #6
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    I used Dikkie's method on mine also, but just used a cleaned Avid bleed kit. But, I also had an old Hayes bleed bottle w/ the spring that helped to keep the hose on the bleed nipple. With the two syringes attached, I was able to pull a vacuum on both levers and very quickly get all the bubbles out of the system.

    If you follow the Avid bleed method (close down and hold down the lever and pull a vacuum at the caliper, then push the degassed oil into the lever and repeat w/ a closed caliper), you can get a super clean, degassed, bleed. The only thing, seal up the master cyl after the 2nd degassing first and then open the caliper and use the caliper's ability to seal things up under pressure to 'tweak' the pad engagement range. It's a bit tedious but works.
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  7. #7
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    Thanks guys, I took it back and he re-bled them and now they work a treat. Very little sponginess and a nice early contact point. I am going to need to learn how to do this myself at some stage!

  8. #8
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    In my little experience with Shimano's brakes I first did a lever swap without the proper bleed kit and got it to work, I then got the bleed kit (after a few years working mainly on Avids with their kit) and have to say I found it worked well and very easy, as good or better than Avid or maybe it's just the better design of them
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  9. #9
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    I've found that after bleeding, and allegedly getting all the air out, the contact point can be wrong. In other words, there's still a long lever pull before pad to rotor contact even if there is no sponginess. I've found that removing the rotor and pulling the lever 1-5 times to get the pistons to "auto adjust" or whatever helps. Do one pull at a time and put the rotor back in and test the feel til it's to your liking.

    I hate bleeding brakes on cars, karts, and now bikes.

  10. #10
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    Hi all, for the last almost 2 years I´been following the Shimano XTR bleeding manual / instructions with the same issue, the levers stoping at the grip. Last week I stope and tried to figure out what could be wrong and I suceeded very well.

    I´m a bike mechanic since 1992 and thinking about how the open air system works (XTR´s are open air due to the overflow hole aside the brake levers) is found a final solution, very simple.

    You may proceed with the Shimano´s bleeding instructions or Avid, both will work. You got think like you were using cable and housing systems, what you did to get more leverage / contact point ? The idea is the same, now you got put more oil inside the hoses / brake travel, but how ?

    After following the bleeding instructions (Shimano or Avid), stop at the time you have to squeeze the brake lever some times with the yellow pad spacer on it.
    *** The Trick: Take out the yellow block, put the pads back and no wheels yet. At this time you got have the funnel filled with oil at the levers, press about 10 - 20 times, doing it, you will put more oil into the hoses, making the pistons go further and keep the oil level at the levers filled. Now take out the funnel, put the screw back and the wheel. Check if the lever reach is ok, if not, still too much travel, repeat the last steps, you don´t need to re-bleed. If few travel, just open the bleed port at the caliper and let some drops go out. Is easy and works pretty well, I tested myself. Sometimes the manufacturer is wrong, believe me.

    Regards,

    Luis

  11. #11
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    FWIW: The brake pads are retracted away from the rotor by the caliper piston seals. With freely moving pistons, properly aligned calipers, and properly reset seals, there can be a fair amount of lever travel to take up that clearance before getting braking action. The lever will move easily until pads come into contact with the rotor then will suddenly firm up. That's normal. If the lever is squishy at that point, then it's air in the system.

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