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I recently replaced the brake pads on my hydraulic disc brake. The brakes are a Tektro Draco 2. Now the new pads are constantly touching the rotor.

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This is how it looks like with caliper unmounted. Notice the left piston is constantly sticking out:

enter image description here

I tried spreading the pistons with a spacer. I left it in there for 3 hours

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But still, the left piston comes out again. I'm thinking about buying a service kit to bleed the system. Will that help?

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Make sure there's absolutely no air in the system. – Daniel R Hicks Dec 7 '13 at 13:36

Before changing to new pads you usually need to reset the pistons to their original position. I'm not familiar with your specific brakes but usually pistons auto adjust in order to compensate for pad wear. That's why right now you get constant rub.

Bleeding will help in case there is a lot of air trapped in the system (and that may be the reason why reseting with the spacer did not work for you). Also, air will expand when the brakes get hot so it'll make this problem even worst. Generally, properly bleeding your brakes is the only way to have good brakes.

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I thought so too so I just bought a service kit for the brakes. – mles Jul 12 '13 at 20:56
up vote 2 down vote accepted

I left the spacer in overnight. The Piston now goes all the way back. Guess I was just too impatient :)

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