don't put WD40 near the calipers, if it gets on the Piston seal, it softens the rubber, making it more prone to tearing, and also may cause swelling of the seals. The caliper is an alloy caliper, boil a kettle, and pour hot water over the caliper where the pins locate, the hot water makes the alloy expand enough for you to knock the pins out safely. also, before you push back the caliper piston, clamp off the rubber brake hose(use a hose clamp ***NOT Vice grips***) pop open the bleed nipple, (the hot water trick will work on this too if it's tight) then gently push back the caliper piston. that way you are not going to run the risk of damaging the master cylinder seals by forcing the fluid through it the wrong way. only use a slight skimming of copper grease on the rear of the pads, this will eliminate any squeeling, and avoid a lot of brake dust sticking to the back of the pads.
Zapp Whyzz
November 2009