2005-2008 Honda ATV TRX500FA/FGA Fourtrax, Rubicon Factory Service Manual, Page 393Get this manual
REAR DRIVING MECHANISM Set horizontal type dial indicator on the ring gear through the oil filler holeTurn the ring gear back and forth with the axle to read backlashSTANDARD: 0.050.25 mm (0.0020.010 in) RING GEAR DIAL INDICATOR
SERVICE LIMIT: 0.4 mm (0.02 in) Remove the dial indicatorTurn the ring gear 120 and measure backlashRepeat this procedure once moreCompare the difference of the three measurementsSERVICE LIMIT: 0.2 mm (0.01 in) If the difference in measurements exceeds the service limit, it indicates that the bearing is not installed squarely, or the case is deformedInspect the bearings and caseIf the backlash is excessive, replace the ring gear right side shim with thinner oneIf the backlash is too small, replace the ring gear right side shim with thicker oneBacklash changed by about 0.06 mm (0.002 in) when thickness of the shim is changed by 0.12 mm (0.005 in)Ring gear shims: A: (thinnest): 1.82 mm (0.072 in) D: (standard): 2.00 mm (0.079 in) I: (thickest): 2.30 mm (0.091 in) Change the left side shim as follows: If the right shim was replaced with 0.12 mm (0.005 in) thicker shim, replace the left shim with one that is 0.12 mm (0.005 in) thinnerLEFT SHIM RIGHT SHIM