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Shimano SLX hydro discs. Front feels spongy and down on power.

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Shimano SLX hydro discs. Front feels spongy and down on power.

Old 01-15-12, 11:32 PM
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ESW116
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Shimano SLX hydro discs. Front feels spongy and down on power.

The story of these brakes is that I bought them as a christmas present to myself for my mountain bike. *Note* I am very happy with them and the only reason they're underperforming is because I know that either the pressure is low or that there's air in them (actually it's just the front - the rear brake feels perfect).

I'm guessing the problem is because the amount of fluid is low, because the front recently leaked. Why did it leak? The mech who installed them apparently did not tighten one of the hoses properly (I normally like doing the work myself, but these were my first hydraulic brakes, and I didn't want to possibly mess something up) and a small amount of fluid came out during a recent ride.

The thing that bothers me is that, although he admitted to the mistake, he insisted that it felt the same as the rear brake (it absolutely doesn't, the rear lever feels firm and strong; the front feels, like I said, spongy and weak.)

I felt like I rambled so the question is: what is the actual problem with my front brake and what should I say if the mech says that he doesn't feel a difference again? (I have a feeling I know the answer to this).
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Old 01-16-12, 10:24 PM
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Sounds like you at least need to bleed the front brake (this would get any air out of the line). Sponginess is usually due to air getting into the line, since air can be compressed (when you apply pressure with the lever), unlike the brake fluid. This is something that you should learn how to do as well, as you'll likely have to do it again.
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Old 01-17-12, 07:05 AM
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if fluid leaks out then air goes in its place.
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Old 01-17-12, 08:01 AM
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Matt Gaunt
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Originally Posted by reptilezs View Post
if fluid leaks out then air goes in its place.
Yep.

Bleed them yourself. It's not tough and then you've acquired another skill in your arsenal.
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Old 01-17-12, 09:23 AM
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You haven't said what version of SLX you have, if you have M666's (2012) these you wil need the M575 kit to assist in the bleeding, the process is similar to this http://cycle.shimano-eu.com/publish/...d_br-m575.html
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