Freeing seized piston: Hope Mono Mini

[moonlite]

Drill small pilot hole in centre of piston.
Find a HEFTY self tapping screw
Find a stout piece of material (metal, maybe wood with washers) and drill it so that the screw thread will pass through freely (but not the screw head)
place the screw through the material and butt that up against the caliper body
find spacers/stack washers so that the screw can screw a fair way into the piston but it can't pull into/through the metal/wood block

tighten the screw and it will pull the piston out.

Nice one -- that's an improvement over my idea of two holes and pliers!

 

[Twozaskars]

I know it’s been said already but I really think the best idea is to rebuild it and pump it out.

 

[My_Teenage_Self]

I know it’s been said already but I really think the best idea is to rebuild it and pump it out.

It should work, but that's going to be messy when & if it goes. Also actually tricky to set up without some specific equipment.

 

[Twozaskars]

It should work, but that's going to be messy when & if it goes. Also actually tricky to set up without some specific equipment.

Can’t you just put an old disc or something similar in the caliper, so the free piston can only travel so far?

 

[moonlite]

Quiet on this subject for a while, although I'm grateful for everyone's good advice. I finally gave up on the stuck piston, but not without putting a whole lot more effort into it -- carefully drilling through the piston (that stuff is incredibly hard) and making the hole into a slot. No matter what I did, though, it just would not shift. I did manage to pull out a few chunks of the piston but the force required made this a risky approach and the problem remained that this approach virtually guaranteed damaging the bore.

So I went on ebay for a replacement caliper. The first one I bought was cancelled by ebay -- apparently it was a 'restricted item'. Then I found another which fit the bill, apart from a few scuffs -- and this one arrived yesterday. So all the parts are here and it just remains for me to build it. Thankfully there's some kind of holiday coming up . . .

 

[elite504]

Exactly what Novocaine said on the first page and twozaskars said above. Put it back together and use a toolmakers clamp (or two) on the non seized piston. Bleed it, then use the hydraulic pressure to push the seized piston out.

 

[novocaine]

Exactly what Novocaine said on the first page and twozaskars said above. Put it back together and use a toolmakers clamp (or two) on the non seized piston. Bleed it, then use the hydraulic pressure to push the seized piston out.

Can't, he drilled a hole through the piston. It's now FUBAR.

 

[moonlite]

Can't, he drilled a hole through the piston. It's now FUBAR.

Unfortunately so. And believe me, both my LBS and I tried that method first without success. This level of surgery was very much a last resort.

 

[novocaine]

Unfortunately so. And believe me, both my LBS and I tried that method first without success. This level of surgery was very much a last resort.

Wanna send it to me for a go? Can't **** it up more than it already is.

 

[moonlite]

Wanna send it to me for a go? Can't **** it up more than it already is.

Thanks mate but I'm about to transfer all the bits and bobs over to the new-old one I bought on eBay . . .