Stubborn caliper bolt

[nikkyboy]

I'm having trouble with a seized top caliper bolt on my 8valve.  Managed to get the bottom one out, but the top one's rounded.

I've tried:
loads of penetrant spray
mole grips - grips evetually give in, slipping off and take chunks out of the bolt
filing the outside edges so I can hammer on a 12mm impact socket - the socket doesn't grip as much as whats seized the bolt, and slides off
hitting it with a hammer (probably wouldn't do much but made me feel better )

I'm stumped...any ideas?

[Dolly]

i got a set of irwin bolt/nut extractors knock the tightest fitting one over the bolts and as it turns it grips. i could believe how well these worked on various exhaust bolts ect.

http://shop.ebay.co.uk/?_from=R40&_trksid=m38.l1313&_nkw=irwin+extractor

[nikkyboy]

they look the business and my local screwfix sell them. I'll give it a try tomorrow and let you know how I get on. Thanks for your help! 

[Jay]

If that fails, Angle Grinder comes to mind 

[Mr Blue]

get a blow torch and heat the bolt.

then smack a splined socket over the whole bolt and unscrew. Works well

[DarnPB]

Drill the head off the bolt, remove the caliper and then tackle the stud that remains, on a bench.

[nige_s]

A Dremel is your friend, great tools for cutting stubborn nuts and bolts of.  Less dramatic than an angle grinder and ideal for tight spaces. 

[richard s]

get some irwins they dont mess about

[nikkyboy]

The irwins did it, took next to no effort, can't believe it!  Thanks all for the advice 

[Dolly]

good aint they