I have bled and re bled my brakes – formula oro K18s – and, on the advice of this forum, used silicone spray to try to lube the pistons at the caliper to allow a better release.

But I’m still struggling to get the pads to return without them staying rubbing on the discs.

What am I doing wrong? any advice gratefully received….
Just for my education is it just the little spring between the pads that should be pushing them back? it’s not exactly super powered but is springing well when removed.

TIA

If you have honestly tried everything else, just get a thinner rotor.

Just a thought, maybe you could be over filling the system with fluid? Therefore the pads can not retract away from the rotors?

If it is IS mount, getting the mounts faced can sometimes help.

Another thought. What pads are you using? It might be that they are a thicker than formula branded pads?

Pads are pushed off by the springs…

Pistons are pulled back by the piston seals…

Hence it’s important to make sure the pistons move easily. I remove the brake pads and then slowly pull the brake lever to get the piston to move out. Then I smear some Brake fluid around the edge of the piston and push the pistons back in. Pump them out again and push back in – repeat this until the pistons move freely. The brake fluid will help lubricate the seals and make the pistons retract properly.

Should solve all your problems.

Thanks all for advice.

Brake fluid or silicone spray to lube the pistons? I may not have given it enough go’s to get the pistons fully moving

I had similar problems with Avid Juicys. What was the clue for me was that once I’d lubricated the pistons (I used silicone grease, applied to the edge of the piston with a cocktail stick) I still couldn’t get them apart enough, but when I pushed one in, the other moved out. So I let a bit of fluid out at the lever. That fixed the clearance issue, the front was perfect but the back had too much lever travel, so I bled it, then it was fine.

Same as I said to somebody here yesterday.. The diaphragm tends to fall to bits, and clog up the port on the master cylinder, making them pump up.

I’d always use the same brake fluid that you fit in the brakes – that way you can be sure of compatibility between the lubricant and the seal.

If you get this wrong the seal material can swell and cause the pistons to jam – this is usually not fixable.

bikewhisperer – so this issue with the diaphragm means they ‘pump up’ and don’t release? This sounds like it could be the issue but they have only been used for the last 18 months or so for mainly commuting, they were new before fitting. Is this something I can reasonably expect to have happened?