I thought I'd have a go at replacing my brake discs and pads myself today while the sun was out. I've had a good read through the Haynes and watched a 'how to..' video here and it seems easy enough, but I've gone and got stuck at the first hurdle... I can't get the bloody calliper retaining bolts out! I'm a total beginner but I can only assume these are the ones that need removing... ...but they just won't shift!? Any ideas?