I could be wrong, but the adapter/caliper probably shouldn't have a washer between them, they're meant to fit specific rotors, so putting a washer there would throw the alignment off.
From
http://www.hayesdiscbrake.com/Stroke...EnglishWeb.pdf
C. Mounting the Caliper to the Frame or Fork
Warning:
When following any of the procedures below, be sure to keep your hands and fingers from getting caught in the disc. Failure to do so could result in injury.
1. Remove the wheel(s).
2. For some installations it will be necessary to mount a mount bracket to accept the HB Disc Brake caliper. Mount the mount bracket to the frame or fork using
(2) M6 x 1.0 18.4mm long mount bolts. Torque the bolts to 110 in-lbs (12.43 Nm).
3. Mount the caliper to the frame or mount bracket using (2) M6 x 1.0 18.4mm long mount bolts and (2) mount washers. Snug the bolts, but leave them loose enough so
that caliper will move on its slots.
Caution
: For post mount forks you will need to use (2) M6 x 1.0 22mm long mount bolts. These bolts are supplied in your aftermarket kit or supplied from the bike
manufacture. Failure to use the longer bolt may result in fork damage that will not allow you to tighten down your caliper properly.
4. Re-install the wheel(s).
5. Squeeze and hold the brake lever. While holding the brake lever, shake the caliper to position it in its natural centered position over the disc. While squeezing the l
ever, tighten the mounting bolts.
Warning
: Do not adjust the caliper while the caliper is hot.
Warning:
Do not adjust the caliper while the wheel is spinning.
6. Release the lever, spin the wheel. Check that it spins freely and that the gaps, between the pad and the disc, are equal. If the gaps are unequal, or if there is drag,
readjust the caliper position by loosening the mounting bolts and adjusting the caliper as needed. Hint: A white piece of paper can be used as a background to help
sight down the disc looking for equal clearance between the pads and disc.
7. When the gaps are equal and the wheel spins freely (without drag), torque the mounting bolts to 110 in-lbs (12.43 Nm).
Caution:
For post mount forks, torque the mounting bolts to 80 in-lbs.
8. Repeat above procedure for other wheel