2005-2008 Honda ATV TRX500FA/FGA Fourtrax, Rubicon Factory Service Manual, Page 369Get this manual
FRONT DRIVING MECHANISM Replace the pinion shim with thicker one if the contact pattern is too high, toward the faceTOO HIGH:
PINION SHIM
Drive side Replace the pinion shim with thinner one if the contact pattern is too low, toward the flankFifteen different thickness shims are available from the thinnest (1.64 mm) shim to the thickest (2.18 mm) shim in increments of 0.06 mm
Coast side