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Really struggling with these brakes now. Just installed new pads, but pistons won't separate far enough to put the wheels back in. Tried pushing the piston in using a plastic tyre remover, but no joy. It seems like one pad (hub side in both cases, front and back) is a lot further out that the other, which suggests sticky pads.

I'm also a bit confused as the pistons move (both pistons on both brakes) as soon as the actuator arm starts moving. I thought they were supposed to have a delay as a valve closed, so I'm wondering if they're actually properly set up at all. I can't see where the bleed valve is though, and if it's opening.

Any advice gratefully received!

Edit; I think there's three problems I'm working on here; i.) The pads are asymmetric; the outside pads are barely showing, the inside ones are protruding by about 2-3mm. ii.) Even with the cable detached and the arms locked out I can't push the protruding pad in. It moves slightly under extreme force, but moves back after the force is removed. iii.) The pads move as soon as the brake lever moves, which I don't think is right.

I'm going to try and clean the edges of the pistons I can get to, as following this you tube video

and see if that helps at all, will report back.

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    Possible duplicate of TRP HY-RD brake pistons won't retract to take new pads – Argenti Apparatus Aug 21 '18 at 23:51
  • If rotor won't fit between pads, pistons must no be retracted. Looks like someone ran into the same problem. Makes sense seeing as you have same problem in both calipers. – Argenti Apparatus Aug 21 '18 at 23:57
  • The other question is probably the same thing but the accepted answer doesn't really get into what's going on. – Nathan Knutson Aug 22 '18 at 3:19
  • @NathanKnutson Agreed. We should close the other question as a dupe of this one. – David Richerby Aug 22 '18 at 11:10
  • My close on this retracted, voted other as dupe of this. – Argenti Apparatus Aug 22 '18 at 14:47
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The big thing about this brake that differentiates it from everything else is you must not under any circumstances use the barrel adjuster to do anything but take out slack from the cable. If you use it to pre-actuate the arm, or in other words to take up pad gap, the brake stops working right. The automatic piston advancement doesn't work correctly anymore and I believe this can happen too.

This is the whole reason they have the lockout knob on the arm. You engage that, pull the cable tight, undo the lockout, and the automatic pad advancement should take care of the rest of the adjustment. The pistons will then also be able to be retracted manually when needed.

So what you should likely do is undo the cable anchor, push the pistons back in as you were attempting to before, screw the barrel adjuster all the way in to its starting point, engage the locking knob, pull the cable tight with a plier, anchor it, and then use the barrel adjuster to get any last little bit of slack out such that when you pull the brake lever, the brake arm immediately starts moving, but not so much that the brake arm's static position is away from its own starting point (you can test this by trying to engage the lockout). Squeeze the lever a bunch of times and the automatic pad advancement should make the system firm up.

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After spending hours looking at these and bleeding them, and talking to my LBS, I think the answer is to switch them out and replace them with Spyres. We've got absolutely nowhere. After three years, they still don't adjust their position with pad wear, so after half a pad they're dangerous. As the mechanic at the LBS said "They're supposed to combine the best of hydraulic and cable, but instead they just combine the worst".

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