Sticking Hydraulics

[Globalti]

Oh dear! "Hope Mini is particularly bad"? Is that because the pistons actually swell over time, do you think? I've just nipped to the garage to dig out an old piston and check the material but I must have thrown the last ones away.

 

[Levo-Lon]

Best and safest way to get pistons out.

Remove pads..
Use a suitable width spacer..single pad usualy works.
pump the pistons so they push out and meet in the middle ...hence the need for a spacer so the tight one will move after the lose one stops moving.

split caliper..pistons will simply just pull out of the bore..
no high pressure or brake fluid risk..

i used this method many times while refurbing tokico calipers, and cycle brakes
works with 2 pot 4 pot and 6 pot brakes ..or any that requires the pistons to be pushed out.
some brakes need a special tool but not for cycle brakes.

 

[Yellow Saddle]

Oh dear! "Hope Mini is particularly bad"? Is that because the pistons actually swell over time, do you think? I've just nipped to the garage to dig out an old piston and check the material but I must have thrown the last ones away.

Hope actually discontinued those brakes, IIRC . I wish I knew more about polymers but I can say that the pistons somehow became rough and kept on sticking, even though to the eye they were not pitted or abraded. The caliper required a special tool to open and get to the pistons and once these came to us for service someone else had usually already attempted the job with a can opener.

The Avids and Hayes' had the same problem - resin pads made from sandpaper or something.

 

[Globalti]

I'm pretty sure all my Hope pistons are alloy with a magnet inside to hold the pads. They have a surprisingly textured finish on the outside.

 

[Yellow Saddle]

I'm pretty sure all my Hope pistons are alloy with a magnet inside to hold the pads. They have a surprisingly textured finish on the outside.

Are you sure those were not Hayes? Hayes mechanical had such a magnetic mechanism to retract the pad with the piston. Nevertherless, I may well be wrong. It has been some years since I've cared about those things.

 

[Globalti]

Definitely original Hope minis. There is also a small M shaped spring but that's more to prevent pad rattle.

 

[Kestevan]

Well, still having problems. The lads in the lbs have seen the problem, but don't have an answer. The lever has also started to play silly buggers on gear changes, sometimes the ratchet engages, sometimes not.

Lbs last comment was bugger this for a game of soldiers, we'll just send it back to Shimano and get a new one.

So still no working bike..

Fortunately the lbs lent me a shiny Trek boone cx bike so I could go and play silly buggers with Kes jnr this morning.

(hats off to cycle technology in Wakefield for top class customer care
- especially as I didn't buy this bike there)