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  1. #1
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    upgrade from XTR 975

    I have a (probably stupid) question. My 3-yr old rear XTR 975 brake is falling apart. It bleeds minute amounts of oil, which requires frequent oil refills and also damages the brake pads. I need to do something about it!

    So, I thought, instead of just replacing the caliper, maybe I could upgrade it to a 985 caliper. Can you tell me whether this is doable (I would rather keep everything else as is, just exchange the rear brake caliper), and - if so - whether it is advisable?

    Many thanks in advance

  2. #2
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    63 views thus far, and nobody volunteers an opinion??

  3. #3
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    Where exactly is it leaking from? If it's a hose then somewhat easy fix.

  4. #4
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    Not entirely sure where. Leakage is minimal, and manifests itself as progressively soft grip (over weeks) and broken slippery pads. Hence I suspect it's the piston seals. But I feel intrigued by the prospect of upgrading the caliper, and 110$ is a loss that I am prepared to suffer...

  5. #5
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    It can be done but you'll need a new brake hose (Shimano BH90) since the caliper fittings are different and most importantly, a new banjo bolt which is specific to the BH90 hose and latest generation SLX, XT & XTR calipers. Once you get it all setup it works just fine.

    Universal Cycles -- Shimano Disc Brake Hose Parts

  6. #6
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    Aerius, you rule! Yours mechanical advice is impressively competent - many thanks!

    I still have a question though. Do I really need to replace the entire hose from the lever to the caliper? I was hoping to be able to avoid that. Can't I just squeeze the new Banjo bolt into the existing hose (after shortening it by 1cm or so)?

  7. #7
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    Unfortunately you will have to replace the entire hose. The M975 brakes use a compression fitting where the hose goes straight into the body of the caliper. The M985 uses a banjo bolt system where the banjo on the end of the hose is bolted into the side of the caliper. Making things even more fun, the banjo on the end of the BH90 hose is slightly different than the one on the older hoses so you have to buy the more expensive BH90 hose (though I do remember a thread where someone had used washers to make the BH63 hose work with XT calipers).

    I also forgot that there's 2 versions of the BH90 hose, the one you need is the BH90-SB which is the one with the banjo fitting for the M985 & 785 brakes.

    M975 caliper & hose fitting
    http://www.coloradocyclist.com/img/p...s/ssmhlt41.jpg

    M985 caliper & hose fitting
    http://www.sicklines.com/news-images..._brakes14s.jpg

    Thanks Shimano, for breaking compatibility and making things a PITA.

  8. #8
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    Thank you Aerius; I got it. My (hopefully final) question is: if the BH90-SB hose is different from the one I have on the M975, will the new hose play nice with the fitting at the other end, where it must fit to the (old) lever? If external or internal diameters differ, I would fear trouble there as well...

  9. #9
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    I'm not sure if the hose itself is different, but it fits fine and works properly with the M975 levers.

  10. #10
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    I have bought the M985, and I have only now realized that it is designed to fit a PM (vertical) post mount. My Cannondale Rize has, however, IS (lateral) brake Mounts. Most adapters appear to be for IS brakes onto PM mounts, but I need the opposite, and there is a bewildering variety of different Mounts. Before I go ahead and order a wrong mount, would a kind soul advise me on what I might need? My rotors are 180mm (front) and 160 (back). Many heartfelt thanks in advance!

  11. #11

  12. #12
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    I have now mounted the new XTR as a rear brake, and I am very happy. The biggest deal is that the PM Mount does not require any shims: it is perfectly centered!!! This was never the case with the old IS-mounted XTR.

    Because I have a new XTR in the back and an old XTR in the front, I can compare them side-by-side. The relationship between lever pressure and brake strength is definitely more linear with the new brake - but this may simply be because the old ones were really worn-out.

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