How do I free a caliper that's siezed onto a disc?

Got me a lovely new -old- Transalp today to do up and go two up with her indoors. First problem I need to overcome is the rear single piston caliper seized onto the disc. Can't shift it. Have given it loads of whacks with a very large adjustable and cardboard to protect it but nothing. Have rocked and rocked the bike too.

Please help!

P.S. I'm not abandoning the SV, meerly keeping it for best!

Assuming it's the pads stuck onto the disc by corrosion, it may be possible by removing the retaining pins to remove the caliper and leave the stuck pads on the disc for removal later.

Don't know if that would be possible, depends on the caliper/disc configuration I'd guess, but I've used the same technique on classic car brakes with success before.

Assuming I'm gonna rebuild the caliper with new seals would using penetrating spray help and be ok?

You could certainly give it a try, but you'd need to make absolutely sure you remove all traces of the penetrating fluid from the disc before fitting the caliper and new pads back on.

And if you don't already have some, PlusGas is your friend, WD40 might work but PG will get the job done much quicker.

Plusgas? I got some 3 in 1 high performance penetrant spray. Would this contaminate the pads so I need new ones then? Couldn't they just be thoroughly cleaned too? They are relatively new pads you see.

Originally Posted by teriyakimonkey

Plusgas? I got some 3 in 1 high performance penetrant spray. Would this contaminate the pads so I need new ones then? Couldn't they just be thoroughly cleaned too? They are relatively new pads you see.

Yeah, PlusGas is uber-penetrant. Never used anything else for real unsticking, so I don't know how the 3-in-1 would compare, but give it a go. Some pads are a little porous, so I personally wouldn't re-use them. For the price of a set of cheap pads, I would replace them to be on the safe side

Tried and failed. Read the Haynes and tried again taking out the pads first and succeeded! I did try the penetrating iol but it didn't get the friction side of the pads. I have wiped clean the piston and caliper as much as possible. Why must only brake cleaner be used to clean brake parts as long as they're rinsed clear of all other cleaners? Am I right in thinking I need a caliper repair kit and then just fit it all up again (after cleaning the discs of course)?

i would try some PB or Kroil and the take the caliper off with a mallet

Someone didn't read my post all the way through! It's now in pieces on my living room table.

Originally Posted by teriyakimonkey

Tried and failed. Read the Haynes and tried again taking out the pads first and succeeded! I did try the penetrating iol but it didn't get the friction side of the pads. I have wiped clean the piston and caliper as much as possible. Why must only brake cleaner be used to clean brake parts as long as they're rinsed clear of all other cleaners? Am I right in thinking I need a caliper repair kit and then just fit it all up again (after cleaning the discs of course)?

Brake cleaner's just a very pure solvent - so it leaves nothing nasty behind. About the only other pure solvent would be carb/FI intake tract cleaner, which doesn't leave lube or gum behind. Brake cleaner will also get rid of pretty much any other cleaner too.