Hayes Nine Hydraulic Disc - won't release rotor

Simon Notley

Went to get my gf's bike out of the shed the other day only to find her rear Hayes Nine brake was jammed on and gripping the rotor so firmly it was hard to turn the wheel. I tried the normal process of pushing the pistons back in (literally the only thing I know how to do with hydraulics), but they just won't go back into their normal position.

It was very hot in the shed, so could it be that there is air in the system and it has expanded? I will check once it is cooler to see if they go back. I tried googling and found a bit about 'stuck pistons', would that describe this problem? They are not stuck as such as they move inwards, just not far enough outwards.

If bleeding is required, I'll probably go to my LBS as I can't be faffed with buying any more tools and kit right now, but just wanted to check if there was anything else I should be trying? Would be nice to get the bike rideable while the weather is good.

nicklouse

release the bleed nipple and catch the fluid that will shoot out. then push the pistons back catching the rest that come out.

then do up the nipple and see how the brakes feel after a couple of pulls.

if crap then a full bleed is needed.

Simon Notley

Thanks, that seems to have worked although I think I release a bit too much as the lever moves a bit too far now.