Messed Up Hope C2 Seal Replacement - Newbie Help

[WiteWulf]

Evening all, I started out what I thought was a relatively simple job and have no idea what I've done wrong. I've got Hope C2 callipers and pro levers on my Pace RC200 F8 and one of the pistons on the rear calliper wasn't retracting properly and rubbing. This seems a pretty common complaint from reading around the Internet, so I thought I'd strip it down, replace the seals while I was at it, and lube it up. I got a proper Hope seal replacement kit off eBay, got both pistons out with a bit of elbow grease and the track pump trick, gently smoothed down a slightly burred edge on one piston with some emery paper, replaced the seals, popped some silicon grease on and screwed the pistons back in. At which point they completely seized solid and refuse to move. I have no idea what I've done, but they won't unscrew now and won't move back and forth.

I've wound up making a right mess of the tops of the pistons trying to unscrew them again with too much force and have given up now. Pretty disappointed with myself for making such a boll*cks of this

FWIW the front calliper is untouched and working just fine.

So, two questions:

- is anyone familiar with this situation and knows a way to free these up again?

or, assuming I've destroyed it and it's beyond repair:

- what are my options for replacing them? I know I'll not get a replacement C2 number 3 calliper easily (although I can keep an eye out on fleabay). If I'm going to replace them with an alternative there appear to be two mounting standards from what I gather: IS and Post mount. The rear mount is 51mm between the mounts, so I guess this is 'IS' (and from it's age, too). The front brake seems to be held on with a combination of brackets on the forks and the axle. Can newer callipers be fitted with adapters and will I need to replace the disc and lever, too? I'd imagine it's sensible to change both front and rear so they match.

 

[WiteWulf]

It's on a motorbike forum, but it looks like I've made the same mistake as this guy and the seal has reacted the with either the grease or the brake cleaner I used before I fitted the new seal (I could have sworn I'd cleaned it out properly), swelled up and seized up the piston:
http://forums.sohc4.net/index.php?topic=46299.0

 

[ishaw]

I'm no expert, but I have some hope brakes and at some point will rebuild them. Research suggested that hope use a specific lube (hunters) for their brakes. I bought some in readiness. Would not have used silicone grease myself.

You should be able to buy replacement pistons if you can get the old ones out.

 

[Bcxbcx]

Damn what a pain! Worst case (and expensive option) but Hope can rebuild them.
What make grease did you use? I just checked the (car) stuff I got for a rebuild and it says its good with brakes (and temperature resistant), but I'm now feeling a little cautious!

 

[WiteWulf]

Thanks, I’ve ordered some of that lube off Amazon and was fortunate enough to find a C2 number 3 calliper and pro lever on eBay that I’ve just won. Looks like this may work out after all.

As for replacing the pistons in the existing calliper, they’re both wedged absolutely solid in the calliper, they’re not going anywhere, sadly, unless I could somehow shrink or dissolve the expanded seal out of the way.

 

[WiteWulf]

What make grease did you use? I just checked the (car) stuff I got for a rebuild and it says its good with brakes (and temperature resistant), but I'm now feeling a little cautious!

No idea, I’m afraid! It was in a jar my Dad gave me, told me it was silicon grease for use on the bike specifically.

 

[boxxer]

Hope seals need specific grease, anything else that’s not DOT compatible will swell up like they do with Mineral oil and bugger the Caliper

 

[WiteWulf]

Got my replacement calliper (and a spare hope sport lever into the deal) off eBay yesterday and fitted it today. It was a bit manky, so stripped it down, cleaned it and fitted new seals (with hunters lube this time!), flushed out the old brake fluid and replaced it and set it all up nicely. It’s working a treat now. Thanks for the help and advice as always, folks.

Expensive lesson learned, but not as bad as if I’d had to replace the whole brake set.