Balancer Shaft
The function of the balancer shafts is to smooth out the engine's oscillations. The balancer shafts are driven by a gear on the crankshaft. The two counter-rotating balancer shafts are located in their own housing in the oil sump. Drive to the balancer shafts is via the crankshaft to one balancer shaft, which in turn drives the second balancer shaft. One of the balancer shafts' gears is two-piece. The "narrow" half (Scissor gear) is spring tensioned in the opposite direction to the "wide" half. It provides silent backlash elimination. This technology is already found in the gear on the B63x4x engine. To ensure correct backlash, the balancer shaft housing is shimmed to the engine block at the assembly plant.