Hope Mono Mini piston stuck

Hi folks. Went to change my pads yesterday and found that the inboard piston won’t retract all the way. It moves in and out fine as long as there’s more than about 5mm showing but once it gets that far in it just stops and won’t go in any further. The outboard piston goes all the way in until it’s flush with the caliper.

As it happens, the piston has a small chip out of the front (pad) surface and I managed to make that worse yesterday whilst faffing about, so I need to replace the piston now. Even so, I’d like to know what’s preventing it going back in any more that it does. I could understand if it had gone back in at an angle and got stuck, but the fact that it goes in and out smoothly to a point and not beyond is what’s puzzling me.

Tried pushing the piston out completely but full movement of the lever/master cylinder piston doesn’t quite push it far enough (with outboard piston held flush).

Two new pistons = a tenner, plus the cap removal tool, plus piston seals, postage – starting to look like about £30 plus a whole load of hassle 🙄 Anyone got a working Mono Mini caliper they want to sell me? 😉

try taking the reservoir cap off, putting a cloth around the reservoir and then pushing it in – it may just be that you’re meeting the point at which all the fluid in the system is compressed as far as it can be.

More likely its a bit of corrosion or damage or dirt on the piston that is preventing it to retract fully

More likely its a bit of corrosion or damage or dirt on the piston that is preventing it to retract fully

Could also be stopping it popping all the way out I guess?

I’d say spend the money and time and fit new pistons and seals – you’ll then have brakes like new (really – I was amazed when I did mine recently) and a smug moral glow 🙂

ill second that… just replaced the rear pistons and seals on my Juicy’s and its transformed the brake (once id managed to bleed it properly!)

and dont forget the red rubber grease on the seals when re-assembling if you do do it 🙂 (can be found on ebay for cheap!)

Fair enough, time for an overhaul then. Don’t think it was a fluid issue as I tried opening the bleed valve with some tubing attached, in case I’d run out of ‘space’ in the system – didn’t make any difference.

CRC are out of stock on Mono Mini pistons. Any other recommendations?

try contacting hope direct?

Just send it back to Hope and forget the hassle. If you have the old type of pistons they’ll replace them for free when they service it anyway. It cost me around £40 for mine which included new pistons,seals,pads & reservoir cap.

Hey, I have the same issue, my old pads were bent around the piston (!) when I removed them and now one piston won’t go all the way back in.
The brake works fine (with less lever travel than I’d like), the wheel spins a few times and stops. This doesn’t in practice really slow me down but I’ll be doing the Passportes in a couple of weeks and I’m concerned that heat build up on long descents will result in the brake locking. Is that possible?
My LBS suggested I do a long descent and with repeated braking it’ll fix itself but I’m sceptical…

Having real probs finding anyone that sells Mono Mini pistons. Anyone know of anywhere? I’ll send it off to Hope if I have to but would rather just order them and fit them myself one evening rather than send the caliper off and be without it for weeks.

http://www.chainreactioncycles.com/Models.aspx?ModelID=9218

Or any bike shop should be able to order them from hope.

CRC have been out of stock for ages. I’ll make some phone calls…

If you send it back to Hope you’ll not wait weeks for it Aftersales is Excellent really quick turnround 😀

recently sent mine back to hope. They were back with me in 2 days after posting them!