1. Lubricate a pair of teeth of the crown drive gear of the main transmission with ink.
2. Rotate the drive gear back and forth while holding the driven gear with a special holder (601 589 01 40 00).
3. Compare the resulting tooth contact patches with the map shown in the illustrations below.
Normal engagement (the result can be considered satisfactory when the contact spots do not extend beyond the edges of the working surfaces of the teeth)
Displacement of contact spots to the bases of the teeth - the base seat size of the drive gear is insufficient (make the appropriate adjustment and repeat the check, having first checked the engagement play - see Section Removal and installation of interwheel differential assemblies with driven gears of final drives)
Displacement of contact spots to the tops of the teeth - the base landing size of the drive gear is excessive (make the appropriate adjustments and repeat the check, having first checked the engagement play - see Section Removing and installing interwheel differential assemblies with driven gears of the main gears)
Shift of contact spots to the heels of the teeth - excessive amount of gear engagement play (make appropriate adjustments - see Section Removal and installation of interwheel differential assemblies with driven gears of final drives, - and check again)
The contact spots are shifted towards the teeth, - the amount of clearance in the gear engagement is insufficient (make the appropriate adjustment, - see Section Removal and installation of interwheel differential assemblies with driven gears of final drives, - and check again)