Hello,

have been greasing up the piston heads of my hayes 9's, one bike is perfect now…
the other is having issues holding pressure:

during greasing one of the piston heads popped out just a little too far and pressure was released, popped the head back in and bled the brake using the proper kit and my own method several times but no matter what i do it wont hold enough pressure:

the heads do move slightly under braking but not enough, lever still touches bar.

Have i **** my calliper?

or any other ideas please!

could it be that i havent seated the heads back into the calliper enough before bleeding?

Have you tried winding in the little screws on the lever?

Sounds like the piston isn't seated properly…when you reinstalled it, did you push the pistons all the way back into the caliper? This needs to be done so that everything is back to 'factory zero', then when you bleed the system the only thing inside the hoses and caliper is fluid and not air – you could have a massive chunk of air still trapped behind the caliper.

I'd drain the system, push the pistons all the way back (I'd get them as far back as possible before draining the system, then try some more once drained) and then I would reverse bleed the brake – put the fluid in at the claiper in instead of the lever end – air travels upwards so by putting the fluid in at the claiper you are using the natural direction of air to help expel it – any air in the system will be forced upwards and out the lever, leaving the caliper end air-free.

Once bled, I'd install some new pads, fit to bike and then give the lever a good few pulls, the first few pulls will be rubbish feeling until the pistons/pads set themselves up then it should be right proper!

cupid stunt- sorry what screws?

dick barton- thanks for the reply i will try that now 😀

Dick, Hayes are bled from the caliper end anyway, but i agree that it is likely there is still air in there – all it can be really, assuming no leaks.

Walla, there are reach adjustment screws in the lever. 2mm allen key ( but use a fresh one as they round out easy at this size! ). unscrewing allows the lever further inwards towards the bar.

bleed them again, give the caliper a good banging around, manipulate it about in all orientations, flick the hose etc. etc. then leave the pads spaced out with something so they are held all the way back, and tie the lever back to the bar as far as it will go, overnight. then try bleeding again. with the lever held back and the system pressurised, any air should gradually make it's way to the top of the system.

HTH.