Help!! Hope C2 brake advice ... Or the dreaded alternative

[BigBailey74]

Hi , I am in the last stages of restoring my Cove Stiffee and the job I dreaded the most is upon me.
I am struggling to un seize my Hope C2 rear brake. I have taken the calliper apart but cant remove the pistons from the halves.. Any tips? I have had it soaking in wd40 and it still won't budge - Does it unscrew? What sort of tool do you use as the aluminium on the piston seems soft as hell.

... Finally IF I cant repair it What period disk brakes could I alternatively find to fit my frame.. I have been told its a rare "odd" fit with the mount on it. (see pic of Brake mount and adaptor) The current C2 calliper is a "type 1" if thats useful to anyone... I would also want the matching front brake on the Fox Talas RL (2004?) forks.. However I would ideally prefer to keep the C2's as I have had them since 2000 and loved them.
Thanks in advance

 

[TreaderSteve]

I can't help you for sure with this particular caliper but WD40 is pretty useless as a penetrant. Plusgas is what you might want to try, if indeed it'll be of any help. Something I remember from a motorcycle forum I was a member of some years ago was grease under pressure dislodges pistons - compressed air was known to push a piston out but at some velocity....! Soaking in diesel is another trick I heard about to undo corrosion/ binding.

 

[BigBailey74]

I can't help you for sure with this particular caliper but WD40 is pretty useless as a penetrant. Plusgas is what you might want to try, if indeed it'll be of any help. Something I remember from a motorcycle forum I was a member of some years ago was grease under pressure dislodges pistons - compressed air was known to push a piston out but at some velocity....! Soaking in diesel is another trick I heard about to undo corrosion/ binding.

Something I did consider was putting it in my ultra sonic cleaning tank in some degreaser.. Would this be worth a try or pointless?

 

[boxxer]

You know the pistons screw in right?

Unscrew with a peg spanner and then pop them with a bit of air to get past the seal…

 

[BigBailey74]

You know the pistons screw in right?

Unscrew with a peg spanner and then pop them with a bit of air to get past the seal…

yes, Stuck solid.. hopefully will be a bit looser later after 24 hours of soaking in wd40

 

[novocaine]

put it all back together then apply an air line to the oil inlet.
pressure baby, you can't beat it. (note, it may only remove one of the buggers, so you might have to get clever with clamp)

 

[BigBailey74]

This morning they are (ever so slightly) moving.. How much you unscrew them and it it in the right direction .. IE not a reverse thread? I am slowly bastardising the holes in the piston as nothings gripping very well. Been trying with circles pliers/ the small pin spanner you use for chain ring bolts

 

[boxxer]

This morning they are (ever so slightly) moving.. How much you unscrew them and it it in the right direction .. IE not a reverse thread? I am slowly bastardising the holes in the piston as nothings gripping very well. Been trying with circles pliers/ the small pin spanner you use for chain ring bolts

You can drill into the piston if needed, there is a ton of material under there

 

[dan28]

warm the alloy body up with a heat gun you dont need alot of heat for this
it will expand when warm should make it easier to unscrew the piston

 

[Chopper the ex Copper]

Freeze it, then attack ot carefully with a heat gun while still frozen.