2005-2008 Honda ATV TRX500FA/FGA Fourtrax, Rubicon Factory Service Manual, Page 366Get this manual
FRONT DRIVING MECHANISM Turn the mm nut and check the pinion gear turns smoothly and quietly without bindingIf the pinion gear does not turn smoothly or quietly, the pinion gear, ring gear or bearing may be damaged or faultyThey must be checked after disassembly; replace them if necessary
BACKLASH INSPECTION
Hold the pinion gear with the mm nutSet the differential case into jig or vise with soft jawsInstall the differential inspection tool into the right side of the differentialTOOL: Differential inspection tool 07KMK-HC50101 or 07KMK-HC5010A (U.S.Aonly) Remove the oil filler cap and set horizontal type dial indicator on the ring gear through the filler holeTurn the ring gear back and forth to measure the backlashSTANDARD: 0.05 0.25 mm (0.002 0.010 in)