Hope mini's sticky ...
 

[Closed] Hope mini's sticky piston

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Hacked off as have just had a reba fitted by LBS but sadly they didn't have time to fix the breaks. Anyway my fault as I know it was a tad temperamental. Question is there anything I can do at home to free it up? It's borderline unridable (wheel turns maybe one rotation before sticking)

Also when it take it in should I ask/assume seals will be replaced when its stripped down

ta

MC


 
Posted : 21/02/2009 6:13 pm
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had the same problem myself when I bought a bike second hand.

A few websites / forums say pump them out and spray qt85, but then some say this contaminates the DOT. I just got the pistons out, cleaned with IPA, actually replaced the rear ones with new phenolic as they are only a fiver from CRC and they were in bad nick, and rebled. Took ages becuase I was new to hydrualic discs, but they work beautifully well now...


 
Posted : 21/02/2009 7:20 pm
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What are phenolic - different brand of piston - sorry if this is a daft question!


 
Posted : 21/02/2009 8:42 pm
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Phenolic pistons are a plastic not Metal ones like you have atm. I have a spare set of phenolic pistons and caliper seals if you are interested.


 
Posted : 21/02/2009 8:47 pm
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May be interested - guess they are new and would be for any version of mini? (mine are 5 -6 years old)

How much were you thinking?

thanks

MC


 
Posted : 21/02/2009 11:50 pm
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Take the pads out and pump the lever a little bit [i]gently[/i] to push the pistons out. You may find one moves more easily - hold it in and pull the lever again to get the other one to move. Clean the exposed part of the piston and lube - some folk use brake fluid - I use silicone / rubber grease. Push piston back in and refit pads - this might work if the piston is not in too bad shape. You can work the piston in and out a few times

Otherwise its a case of removing the pistons completely and cleaning them up - if you do this you might get away without new seals but I wouldn't do it without new seals to hand as seals are cheap and there is a good chance you will damage the seals.

Don't use GT85 or similar to lube the pistons - it might contaminate the seals and make them either swell or leak.


 
Posted : 22/02/2009 12:07 am
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cheers TD but PK_XC sorted me out with some new pistons.


 
Posted : 22/02/2009 8:29 pm