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PostPosted: Sat Jan 19, 2013 6:31 pm 
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Joined: Fri Jun 10, 2011 8:21 pm
Posts: 283
Location: London / Brighton
Ok, so having a nightmare with some Hayes Stroker Carbon hydraulic brakes.

The pistons were not moving well so I decided to try and sort them out by pumping them out of their bores to add Dot 4 fluid around them and then easing them back in. To cut a long story short I now have the caliper pulled apart and one piston stuck firmly in its bore. Normally Hayes suggests pumping the pistons out with compressed air by attaching the compressor hose to the banjo hole or bleed nipple and blocking off the connector hole through to the other half of the calliper with a finger. This is not working at all! I have tried for hours trying various sealing methods but firstly it is hard to get a perfect seal at the banjo hole with an air compressor hose or a track pump, and secondly the finger blocking the other hole is not good enough either.

Even when I do get some pressure going in, the piston doesn't move even a bit. It looks like it is stuck solid. I tried pulling it by its central pin but the pin just came away. I have tried a variety of pliers around the small bit of protruding edge but the ceramic coating just crumbles and its impossible to get much of a grip.

Image
Image

By the way, I tried before I took any of this apart, pumping the brake lever lots to try and push the piston out with the fluid but that didn't work either. I also tried putting the calliper in a boiling kettle and then pumping the air through - no luck either. I have not tried freezing it but I have little faith in those spray can penetrating fluid things.

One bit of hope was that the piston was protruding more when I had originally pumped it with the brake intact, but I then added Dot fluid around the bit that was out and pushed it back in to try and lubricate the bore - now it won't come out at all.

This is the clean bore from the other half of the calliper -
Image

The only things I can think of at this stage is using some JB Weld to try and stick a bar onto the piston and pull it out, but I don't expect even JB Weld to stay attached to that flaky ceramic coating.

Any other ideas anyone?
Thanks


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PostPosted: Sat Jan 19, 2013 8:48 pm 
retrobike rider
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Joined: Tue Jul 14, 2009 7:52 pm
Posts: 1904
Location: Trancecentral
I had the same issues with a hayes nine.
I lay the caliper flat, used a small wood chisel and whacked the plastic piston making sure not to touch the sides of the bore. The plastic is the hard brittle type which smashed easily allowing the but to be easily removed.

New puston kit from CRC came with rubber seal ring, all is fine with mine niw.


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PostPosted: Sat Jan 19, 2013 8:52 pm 
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Joined: Fri Jan 12, 2007 1:32 pm
Posts: 1953
Location: Staffordshire
When I had a similar issue with my old HFX brakes, I just used to smash the pistons.

I'd use a small screwdriver or similar, place it on the centre of the piston and hit it with a hammer until it cracks and then lever the broken bits out. I was tod to do this by a chap from Hotlines.

Hope that makes sense.


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PostPosted: Sat Jan 19, 2013 8:52 pm 
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Joined: Fri Jan 12, 2007 1:32 pm
Posts: 1953
Location: Staffordshire
stewlewis wrote:
I had the same issues with a hayes nine.
I lay the caliper flat, used a small wood chisel and whacked the plastic piston making sure not to touch the sides of the bore. The plastic is the hard brittle type which smashed easily allowing the but to be easily removed.

New puston kit from CRC came with rubber seal ring, all is fine with mine niw.


Beat me to it!


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PostPosted: Sun Jan 20, 2013 1:34 am 
Retro Guru

Joined: Fri Jun 10, 2011 8:21 pm
Posts: 283
Location: London / Brighton
Nice one. Thanks! I will try it tomorrow.


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PostPosted: Sun Jan 20, 2013 2:14 am 
Gold Trader
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Joined: Sat Mar 06, 2010 12:40 am
Posts: 896
Location: Away wi the fairies
Hayes and seized pistons :x

I use a self tapper screw and yank on that, or if you take the screw out once you've started the thread then flatten the point of the screw you can be brave and turn the screw in to push the piston out.


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