I've approx 3 year old set of mono minis. One of the pistons is stuck fully retracted. Does anyone how to sort this out as I can't see anywhere to hammer, lever and swearing at it hasn't helped so far?

Perhaps the easy option is to bin in and buy a replacement caliper.

Thanks in advance

Which side? If it's bore cap side then pop the bore cap off.

It it's not then its a bit trickier. I did it by pumping out the moving one, then adding more fluid, and pushing the moving one back in, the pressure pushes the stuck one out.

If it's really stuck then can you removing the bore cap side, then

*** maybe a stupid idea ***

drill it, tap it, put a bolt in and pull it out with the bolt. Mew pistons are quite cheap, and you are going to chuck it anyway. It might crack when you drill it and then you can remove the bits.

You can pull the old seals out with an o-ring pick, orbig needle.

Good luck (I found fitting new seals was really fiddly when I cracked a piston).

If you put something to clamp the free piston and pull the lever is it likely that the piston would move or is it really stuck

mm its the side which doesn't have a cap.
Clamping the other side sounds good but I can't think how to clamp it.

I'd chuck it but I suspect the caliper isn't available anymore – everythings gone postmount now…hummmmmm

thanks for the replies folks

I would hold the moving piston in place with needle-nose pliers or similar and pump the brake, as above. That should get the bugger moving. Then clean and lube with DOT 4.

Works for me,

APF

Not sure of the mechanics of doing it on a bike caliper but fellas on motorbike forums with big seized calipers used to attach a grease gun and use that to pump out seized pistons. I don't think many things resist that approach.

Multiple tie wraps to hold the "free" piston in, then pump out using the lever. If you've already taken the caliper off, you can use compressed air to blow it out BUT don't let your fingers get anywhere near the gap when you do it (unless you want to discover the difference between A&E and Minor Injuries Clinics).

If that doesn't work – LBS or motorbike shop – happens all the time on motorbikes ridden through the winter

First off I'd leave it soaking in something like Plus-Gas or paraffin for a day or so & then try blowing it out with an airline

Failing everything – Hope are good value when it comes to servicing & repairs

personally id try a healthy plus gas approach if that doesnt work strip for spares/ebay it and get a new 1 hope do caliper adapters for all fitments i.s. post and sizes for rotars.