You likely need to push pistons in calipers "out" so new pads will
> fit. Maybe your FLAPS has a tool for this?
>
>   Don't let anyone step on your brake pedal when the pads are out or when
the disc is not between the pads in the calipers.  Replace the pads before
you do any bleeding or topping up of the brake res.  When you put in the new
pads (thicker) you will be pushing your brake caliper pistons further
in..forcing the level of the brake reservoir to rise..

  I found a nice stick is good for forcing back the new pad and pistons.  I
used a piece of oak scrap about 10" long, 3/4" wide and about 3/8" thick.
The wood won't mar your brake pad compound or the caliper..wherever you can
get leverage to push the pistons and pads back.  I like to carefully use
some VHT anti-seize where the pads fit into their retainers to make sure
they are truly 'floating' around and don't get hung up off center or
something.  Don't get any on the friction material or the rotors.

  You should 'bed-in' new pads and rotors according to instructions.
Usually some easy stops, gradually increasing in intensity of brake force..
You want to avoid descending a huge pass or racing your Vanagon on the
racecourse until you have some moderate braking allowing the pads to seat
and the rotors to season it's surface.
  Don Hanson