The differentials in transaxles are constructed like and perform the same function as those found on rear wheel drive vehicles. Use an inch pound torque wrench to check preload. Helical gears are typical in final drive assemblies. The ring gear should be checked for backlash using a dial indicator. Always compare readings with manufacturer specifications. The collapsible pinion shaft spacer can not be reused; it should be replaced once removed.
Planetary final drive assemblies are checked similar to the helical type. These gears should be inspected for chipping and wear. Use a feeler gauge to check the pinion gears and roll them against an even surface to check for smoothness. If these gears are loose on the shaft, there will be a whining noise when their placed under a load. These gears are often colored blue from the manufacturer, but will turn blue/black from excessive heat. The pinions can get loose on their shafts. When this happens, the entire carrier must be replaced, they’re not sold separately.
Some transaxles use a chain and sprockets to drive the transfer gear. These chains are checked for play or slack by deflecting the chain up using a screwdriver, and then marking the case. Then moving the chain down and marking the case again. The sum of the two is the total amount of chain slack. There’s little deflection in a good chain. Some transaxles use transfer gears instead of drive chains to achieve the same results; transfer of power from the output shaft to the transfer shaft.