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  1. #1
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    help bleeding XT 4-piston

    I have the older XT quad piston calipers and I need to bleed the front. All the instructions I've read say that you attach a hose(got one) to the end of the bleed nipple, squeeze the lever, then loosen and tighten the bleed nut and the bubbles should go into the hose. When I do this, all that seems to happen is that mineral oil goes into the hose, no bubbles and I'm afraid I'm just squeezing all the mineral oil out of the system.

    Any advice?

    Thanks in advance.

  2. #2
    Lopen is sneller....
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    Shimano is selling a bleedingkit. Inside this kit, you can find pictures for the correct bleedingprocedure.

  3. #3
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    Quote Originally Posted by Uzzi
    Shimano is selling a bleedingkit. Inside this kit, you can find pictures for the correct bleedingprocedure.
    Thanks. I have their 'kit' which consists of mineral oil and the little plastic tube. I follow the directions, but was curious what other people's experience was, especially in light of the results I described in my post.

  4. #4
    indigosky
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    I just did this last night...

    Quote Originally Posted by ashayk
    I have the older XT quad piston calipers and I need to bleed the front. All the instructions I've read say that you attach a hose(got one) to the end of the bleed nipple, squeeze the lever, then loosen and tighten the bleed nut and the bubbles should go into the hose. When I do this, all that seems to happen is that mineral oil goes into the hose, no bubbles and I'm afraid I'm just squeezing all the mineral oil out of the system.

    Any advice?

    Thanks in advance.
    Try not having the caliper mounted to the fork, just have it hanging there with the orange spacer thing between the pads. Tap the caliper with something to dislodge the bubbles, and try opening up the bleed nipple, squeezing the lever a few times while changing the position of the caliper (to facilitate bubble exit). close up the nipple and add more fluid to the lever. It took me 20minutes for my front one last night and over an hour on the rear, until I took the caliper off the frame, then bingo! Good luck.

  5. #5
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    The easieest way to do it ;
    Practically guaranteed to get rid of air.
    1. remove pads.
    2, Extend pistons slightly evenly , making sure one side does not pop out.
    3. Take the cap off the master cyl and place bowls /rags etc below master cyl.
    4. Fill a largeish (20cc+) syringe with hydr oil and a hose removing all trapped air from the syringe and hose.
    5. Attach syringe and hose to caliper at bleed nipple, pump master a couple of times, youll see a bubble or 2 appear at the syringe,
    6. Invert hte syringe so bubble is at the top. Pump the syringe to force the oil all the way up through to the master stopping before you hit those bubbles.
    7. Tighten the bleed, reinstall master cap and clean up the mess
    Works like a charm.

  6. #6
    indigosky
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    Pita?!?!?

    Quote Originally Posted by heatstroke
    The easieest way to do it ;
    No offense, but Wow, that sounds like a holy PITA!

  7. #7
    just along for the ride
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    Its good advice cause getting trapped air out of the caliper is key. I just pump up the lever and tie it levered down then quickly open close the bleed nut. Also helps to have the caliper hanging straight down and tilted so the air would be at the bleed nut. I can see where using a syringe to pump/draw out the air would make it easier/faster. Sometimes the bubbles are very small, but its got to get out to keep a nice firm lever and no vapor locking/dragging from unretracting pistons.

  8. #8
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    Awesome

    Quote Originally Posted by heatstroke
    The easieest way to do it ;
    Practically guaranteed to get rid of air.
    1. remove pads.
    2, Extend pistons slightly evenly , making sure one side does not pop out.
    3. Take the cap off the master cyl and place bowls /rags etc below master cyl.
    4. Fill a largeish (20cc+) syringe with hydr oil and a hose removing all trapped air from the syringe and hose.
    5. Attach syringe and hose to caliper at bleed nipple, pump master a couple of times, youll see a bubble or 2 appear at the syringe,
    6. Invert hte syringe so bubble is at the top. Pump the syringe to force the oil all the way up through to the master stopping before you hit those bubbles.
    7. Tighten the bleed, reinstall master cap and clean up the mess
    Works like a charm.
    Wow, that's fantastic. Thanks. One question. Since the master cylinder cap is still off, how do you avoid trapping air as you close it? Or is this irrelevant?

    Thanks.

  9. #9
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    Not relevant, since that reservoir is above the master cyl and not compressed when you squeeze down on the lever. Also if you just loosen the screws on the master cyl when you pump the syringe, the hydro oil can just squeeze out of the reservoir. unlikely to trap air.

    I dont think this is PITA. Compared to the normal approach where you have to pump lever, open bleed, close bleed. and repeat every time checking you do not suck in air cause the master cyl reservoir is emptied. I find my way is a bit faster but more messy/wastefull, but you'll only need to do it once.

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