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Discussion Starter · #1 ·
Hey guys recently I took a spill and smashed my shimano xt rear brake lever in. Now its spongy and has a longer free stroke The free stroke is as low as it can go and the brakes are brand new. What do you think is the problem. Thx
 

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Magically Delicious
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They are hydraulic xt brakes they are the 2013 models with ice tech.
Cable stretch won't apply in this case...that's on mechanical brakes.

You've looked things over around the master cylinder and can see no indication of any fluid leakage, correct? Assuming no leakage of any type my assumption is that air has created the problem. I would assume that your brake reservoir was a bit low and during the upset, excessive air in the master cylinder reservoir found its way past the piston and into the line. I've experienced this too once.

My suggestion would be to try and work the master cylinder to self-purge some air if possible followed by topping off the reservoir. Fortunately, this is must easier and more likely to work on the XT's when compared to some other brakes. Again, assuming no leakage, worst case scenario is doing a bleed job. Bleeding the XT's are pretty straight forward. Lot's on these forums on that.
 

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Discussion Starter · #7 ·
Hey guys I haven't posted in a while because I've been busy. Cleared 2 land I'm a noob to brakes and was wondering if you or someone else who reads this could explain how to purge a master cylinder. Thanks
 

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Magically Delicious
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Hey guys I haven't posted in a while because I've been busy. Cleared 2 land I'm a noob to brakes and was wondering if you or someone else who reads this could explain how to purge a master cylinder. Thanks
My use of the word 'purge' is somewhat nebulous. I used the purge as opposed to 'bleed'. What I mean by purge is not really a full-blown bleed job. On the XT's, the reservoir has gotten a bit too low and air has likely mixed with brake fluid in the master cylinder reservoir during a crash or on a rough section of trail. This air has found its way into the master cylinder piston and perhaps slightly into the brake line. Fortunately, the air is most likely trapped in the upper portion of the brake system.

If this is the case, and I suspect it is, then often you can just pump the brakes several times or until the trapped air has reversed its way back through the master cylinder piston and into the reservoir. By doing this you are purging the master cylinder to get the air out. Then top off your reservoir to prevent any future re-occurrences.

Chances are that you won't need a full bleed given the circumstances that caused the problem.
 

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Elitest thrill junkie
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It leaked a tiny bit or sucked air in, you wouldn't be able to detect that small of a leakage, but levers don't do what you desribed without one of the above happening. Needs at least a rebelled, possibly new seals/olives/compression ring.
 
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