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  1. #1
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    XTR caliper explaination

    Refer to this image for this question:


    In the image above, there's a large screw - the same bolt appears on the XT caliper. I'm told it's used for adjusting the position of the pistons. Is this correct - I've never seen it used for any reason, nor can I find any documentation that refers to it.

    If that's true, what tool is used? Better yet, is there a Shimano tech doc I've missed which explains what it is? I can't find any mention of it in the manual either.

    Is there a chance it's purely cosmetic or not intended to be touched?
    Quote Originally Posted by tom2304
    Yep farkin.net is mostly immature kids asking how to put dual crown forks on hardtails and such.

  2. #2
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    I wouldn't touch that. If you remove it, you will spill the oil.

  3. #3
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    Isn't that used to access the pistons and allow installation?

  4. #4
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    Quote Originally Posted by akashra
    Refer to this image for this question:


    In the image above, there's a large screw - the same bolt appears on the XT caliper. I'm told it's used for adjusting the position of the pistons. Is this correct - I've never seen it used for any reason, nor can I find any documentation that refers to it.

    If that's true, what tool is used? Better yet, is there a Shimano tech doc I've missed which explains what it is? I can't find any mention of it in the manual either.

    Is there a chance it's purely cosmetic or not intended to be touched?
    dont touch that bolt,all adjustments are done at the lever

  5. #5
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    THat's the bore cap

    Quote Originally Posted by akashra
    Refer to this image for this question:


    In the image above, there's a large screw - the same bolt appears on the XT caliper. I'm told it's used for adjusting the position of the pistons. Is this correct - I've never seen it used for any reason, nor can I find any documentation that refers to it.

    If that's true, what tool is used? Better yet, is there a Shimano tech doc I've missed which explains what it is? I can't find any mention of it in the manual either.

    Is there a chance it's purely cosmetic or not intended to be touched?
    as others said, but maybe didn't explain... that is the bore cap. They machine a hole down the middle of the caliper for the pistons and seals, then seal it up with that threaded funky star tool cap. You would only remove that cap to remove the pistons and seals if you are rebuilding your caliper.

  6. #6
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    The 5 pointed star plug is to allow access to pistons since this is a monobloc caliper. I tried to find the rebuild kit to show you but I guess Shimano doesn't want you to rebuild their calipers.

  7. #7
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    That's one thing I don't understand about them. Someone's got to make a kit to pick up the slack.

  8. #8
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    Maybe shimano pistons are so good there's not really a market for that.... or shimano will sue anyone who tries.

  9. #9
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    It DOES NOT adjust the pistons. The pistons are self adjusting. As mentioned it is merely a bore cap. Since the caliper is not 2 halves joined by bolts, you need to have the cap to access the pistons.

    Shimano does not have rebuild kits or parts available.

  10. #10
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    Well that about clears it up - thanks guys.

    Basically I was looking for some ways to better tweak my levers - I don't like the amount of free throw the lever has, it's stopping me being able to brake smoothly into corners as I can't get the position at which they grab accurate each time.
    Quote Originally Posted by tom2304
    Yep farkin.net is mostly immature kids asking how to put dual crown forks on hardtails and such.

  11. #11
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    Quote Originally Posted by akashra
    Well that about clears it up - thanks guys.

    Basically I was looking for some ways to better tweak my levers - I don't like the amount of free throw the lever has, it's stopping me being able to brake smoothly into corners as I can't get the position at which they grab accurate each time.
    Have you checked under the resevoir covers? Sounds like they didn't get enough fluid in the system or you had a bad bleed and there is air pockets in your resevoir. I moved to a narrower rotor than the centelock and I had to open the covers and add a tad more mineral oil to the resevoirs. Workded like a champ.

  12. #12
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    I've noticed a similar effect due to pad wear. As my pads wear, my levers get mushier but firm back up after replacing the pads. I suspect the reason for this is due to the system needing more oil as the pistons extend further and further as they compensate for the pad wear. Why this is exactly, is still a mystery to me.

    On one hand, I assume that the lever feel should remain constant so long as there are no air bubbles between the master piston all the way to the slave pistons at the rotor - regardless of how far the caliper pistons are extended.

    On the other hand, maybe the lever grows mushier as the pads wear and the pistons extend - because of a possible vacuum effect. Perhaps a vacuum builds up in the system as a finite amount of hydraulic fluid is forced to to fill an expanding volume (I realize that fluids are essentially incompressible, so this is more of a visualization aid than what's actually happening). Topping up with oil removes the the vacuum and allows the system to operate..um...better. All conjecture - anyone know what's actually going on?
    Never cross a river because it is on average 4 feet deep.

  13. #13
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    Quote Originally Posted by XSL_WiLL
    Shimano does not have rebuild kits or parts available.
    I'm sure you will find their rebuild kit listed in the catalog under "new caliper"

  14. #14
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    Anyone tried getting the pistons out, themselves?
    Last edited by fallzboater; 05-02-2009 at 05:32 PM.

  15. #15
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    Quote Originally Posted by fallzboater
    Anyone tried getting the pistons out, themselves?

    remove the wheel and brake pads
    squeeze the lever untill it pops out
    you will lose fluid and make a mess

  16. #16
    mnt bike laws of physics
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    seals?

    So, does anyone know where to get seals for these calipers (xtr)?

    I'm pretty sure mine are done since new pads are only working for about 2 rides before the pads are fading enough to render them useless. IOW, they are getting contaminated with oil from the calipers and the only place it could be leaking is the piston seals.

    Not at all interested in buying new calipers, but I guess if that is a last resort
    Are calipers for this model even available?

  17. #17
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    Shimano does not offer rebuild kits for their brakes.
    You can still buy these calipers new.

  18. #18
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    Quote Originally Posted by yogiprophet View Post
    Not at all interested in buying new calipers, but I guess if that is a last resort
    Are calipers for this model even available?
    They are:

    http://viewer.zmags.com/publication/...#/0f36a06c/148

  19. #19
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    Quote Originally Posted by yogiprophet View Post
    So, does anyone know where to get seals for these calipers (xtr)?

    I'm pretty sure mine are done since new pads are only working for about 2 rides before the pads are fading enough to render them useless. IOW, they are getting contaminated with oil from the calipers and the only place it could be leaking is the piston seals.

    Not at all interested in buying new calipers, but I guess if that is a last resort
    Are calipers for this model even available?

    nowhere, they dont sell those parts, they do have a 3 year warranty and will give you a brand new one

  20. #20
    mnt bike laws of physics
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    Quote Originally Posted by Maadjurguer View Post
    Nice find
    Strange thing is I have two 160mm calipers and they are only sold in pairs 160/140 or 180/160. Not interested in those combos.

  21. #21
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    Quote Originally Posted by dan0 View Post
    remove the wheel and brake pads
    squeeze the lever untill it pops out
    you will lose fluid and make a mess
    Iīve been there...
    No, seriously, some time ago just felt the need to remove the pistons. Why? Just becouse sometimes I need to get the things completely disassembled, curiosity, stupidity, a mix of both. Thatīs how Iīve learned 99% of the wrench work I do.And I do all of it on my bike.
    "Blessed is the man who, having nothing to say, abstains from giving us wordly evidence of the fact." George Elliot

  22. #22
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    Quote Originally Posted by yogiprophet View Post
    Nice find
    Strange thing is I have two 160mm calipers and they are only sold in pairs 160/140 or 180/160. Not interested in those combos.


    not true
    http://www.chainreactioncycles.com/M...?ModelID=45525

    the 160/140 means its 160 front or 140 rear without adaptors, same with the 180/160
    they sell individual calipers most everywhere

  23. #23
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    Use a simple allen key that fits.
    Shimano does not sell seal rebuilding kits.

  24. #24
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    Quote Originally Posted by egebhardt View Post
    Use a simple allen key that fits.
    Shimano does not sell seal rebuilding kits.
    Allen (hex) key has 6 sides. Shimano bolt you see there is 5 sides.

  25. #25
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    Quote Originally Posted by the-one1 View Post
    Allen (hex) key has 6 sides. Shimano bolt you see there is 5 sides.
    Oh. My mistake. 5-sides.
    Kinda like BMW and their special 5-sided allen to remove stereo systems.

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