[Closed] Hayes 9 - Pistons not returning.

My Hayes nine pistons got corroded after a bit and started to stick, not sure if this is a general problem - take it you've had the pistons all the way out and lubricated with brake fluid? You could also try and gently file the piston down a wee bit to take any rough edges off.

OEM Hayes nine were pretty cheap on CRC a while back - £35 for brake and caliper IIRC.

Mine used to get sticky, take the pads out, pump the brake a bit, put some brake fluid on the pistons and return back into the caliper.

just fitted new pads? is so, 'tadts', otherwise you can try applying some brake fluid to the sides of the pistons, then pushing them back, and repeat. also, if only one is sticking ( quite common IME ), hold that one in, and allow the other to move outwards when you apply the lever. carefully does it though, cos you don't want the piston popping out altogether!

It's possible that you have a little too much fluid in the system if the problem has occured since you've fitted new pads, otherwise you've probably got sticking pistons. You may be able to bodge a short term repair using the above methods(use silicone lube, not brake fluid, DOT fluid is corrosive when exposed to the atmosphere, and can corrode the caliper body where the seals sit, and when aluminium corrodes, it expands and will create an even stickier piston). A longer term solution is to strip the caliper completely, clean and lube everything, and re-assemble(with new parts if needed), once you see the accumulated filth in the seal grooves you'll understand why just adding lube is a bodge that creates a lovely grinding paste for the piston to run on.

It's possible that you have a little too much fluid in the system if the problem has occured since you've fitted new pads

I always found this was a regular problem with Hayes 9's, some aftermarket pads were just thicker than others. Popping the lever horizontal (as you would to bleed the system), remove the bleed hole "stopper" on the lever and push the pistons back again to fix..

Though as above corrosion is another regular problem with them, and may not be helping the situation.

Typical Hayes issue. Was why I ditched them, despite liking their feel.

Common issue for me was corroded / gunged up pistons ... or what also happens is the dirt and grime sticks to the side of the pistons, bakes on and is too solid to be wiped off by the self retraction of the piston, thereby preventing the piston from sliding back into the caliper.

Getting a cotton bud and thoroughly cleaning the outside outside edge that slides back in helped a lot for me. I used all sorts from brake fluid to degreaser type liquids to break down the grime stuck on.