Check a gap between a flange 33 and a conic gear wheel of a power shaft 17. If it is necessary, establish a lock ring 30a more thinly or more thickly. Thickness of a lock ring changes from 1.4 mm to 2.7 mm with a step of 0.05 mm. A gap between a flange and the case of differential: 0.03 - 0.3 mm.