First off this is what the front caliper/s looks like..




This is an picture of the passenger side inc ware sensor..

OK so first of all you need to get the car up on axle stands with the wheels off..

We will deal with the drivers side for this guide so turn your steering on a right lock so the brake pads are seen either side of the disc..now look at the caliper and you will see its in two parts ..there are two bolts that need to be removed[ right hand side of the first pic]..these need to come out and a 13mm spanner does the job quite nicely ..use a combination one ..thats one with a ring one side and an open end the other..OK you got those out..what kept you ! !..now carefully prise up the top section of the caliper it has the hydraulic brake hose connected to it so its going no where ..turn it over and you will see the piston..



There you go a nice clean new one for you to look at..

Now its time to push that piston back in and to do it I do this..but before you do you need to clamp the brake hose and open the bleed nipple to expel all fluid out of the bleed nipple..pushing fluid back through the system can have a bad effect on the ABS system..



This way you dont push it in to far Ooh err madam.... you should have the cap off of the brake fluid master cylinder so see if the fluid rises as you push that piston in if it does come up to far you will need to remove some ..I use an old plastic hypodermic from my friendly druggie at the bottom of the street..
Now you can hang this top part up out of the way while you go about changing the pads over.. I use a hook made from some wire or a plastic cable tie to hold the caliper out of the way..

First prise out the back pad..its located into metal clips one at the top and one at the the bottom ..once out give all the bits and those clips a good clean up and as much of the brake dust and debris out as possible..now smear some copper grease into those clips I was telling you about and dont get any on the disc ..thats right in the channel of the clips ..well done....now you can insert the pad into the back side of the caliper ..
Next go to the front pad and remove that one ..prise this one out at the edge and tilt it at a 45 degree angle to get it out..I know its fiddly but it will come out..time to clean out those little clips again and all around where there is dust..dont breath it in [cough ] if you can help it [cough] smear some more copper grease to the front clips and insert the new pad here at the same angle as it came out ..its fiddly I know but what comes out goes back in I assure you..
Now you have both the pads in with no grease on the disc..if there is then wipe it off..now smear some copper grease to the backs of both pads if you look at the old ones you will see a circle where the caliper piston has been pressing..yes thats a hint..

With all this done you can now bring the top section of the caliper back down and fit it on top of the bottom section insert the two 13mm bolts and tighten them up nice and hard..have a general look at you handy work and if all seems ok sit in the car and pump up the brake pedal until its nice and hard..you have now pushed the piston out into its correct position so check if the brake fluid need topping up to the max mark on the fluid reservoir..your job is now complete on the one side and you deserve a nice cup of tea ..before completing the next side which is the same procedure except for the unclasping and reconnecting of the brake pad ware sensor..

Cheers..