This comprehensive 52-page PDF file contains the official VAG Self-Study Program 476 (SSP 476), focused entirely on the development and mechanical function of the rear axle final drive units 0BF and 0BE, famously marketed as the Audi “Sport Differential”. Introduced on high-performance longitudinal quattro vehicles (such as the B8 S4/S5, C7 S6/S7, and the D4 A8), the Sport Differential represents a massive leap in handling dynamics. Instead of relying on the brakes to simulate torque vectoring, this active differential utilizes planetary gearsets and hydraulic clutches to physically push more power to the outside rear wheel during a turn, actively steering the car into the corner and eliminating understeer. This technical training manual is an absolute must-have for VAG technicians, diagnostic specialists, and Audi performance enthusiasts.
Please note: As a Self-Study Program, this document focuses on engineering design, hydraulic layouts, and operational theory. It is not a step-by-step rebuild or workshop manual, though the foundational knowledge it provides is crucial for diagnosing complex all-wheel-drive or handling faults.
This detailed technical training manual covers the following key engineering topics:
- The Physics of Torque Vectoring: An introduction to the basic physical principles behind the Sport Differential, explaining yaw rates, understeer/oversteer, and how selectively distributing power to the rear wheels fundamentally alters the vehicle’s cornering trajectory.
- Mechanical Design and Components: A deep dive into the physical construction of the 0BF/0BE units. It meticulously details the internal layout, including the central final drive, the two planetary gearsets (superposition gears) on either side, and the multi-plate clutches (speed modulation units) that actuate the torque transfer.
- Electro-Hydraulic Actuation: The core of the active system. It explains the design and function of the hydraulic pump, the pressure reservoirs, and the proportional valves controlled by the All-Wheel Drive Control Unit (J492).
- Dual Oil Circuits: Essential reading for servicing the differential. It maps out the separate and distinct lubrication systems: the traditional gear oil circuit used for the central differential ring/pinion, and the dedicated ATF (Automatic Transmission Fluid) circuit required for the hydraulic pump and the multi-plate clutches.
- Sensors and Diagnostics: An overview of the specific sensors used to monitor the differential, including the two oil pressure and oil temperature senders required to calibrate the system via the control unit.
Whether you are trying to understand the exact fluid separation between the gear oil and ATF, diagnosing a fault in the hydraulic proportional valves, or simply want to appreciate the engineering that makes an Audi S4 corner on rails, SSP 476 is the definitive technical resource.
CONTENTS
- Basic physical principles
- Basic principles of lateral torque distribution
- Possibilities of the torque overlay differential (sports differential)
- Operation – functions
- Audi drive select
- System overview
- Technical data
- Final drive cutaway
- Torque overlay gear (internal gear)
- Multiplate clutch
- Power flow and handling dynamics
- Oil systems
- Overview
- Oil system junctions in sports differential 0BF
- Oil system junctions in sports differential 0BE
- Hydraulic control system
- Hydraulic control unit
- Overview of components
- Hydraulic circuit diagram
- Hydraulic function control settings
- Sensors and actuators
- Oil pressure and temperature sensor G437/G640
- Pump for all-wheel-drive system V415
- Hydraulic pump
- Clutch valve for all-wheel-drive system N445/N446
- Pressure limiting valves
- Electrical control system
- Function diagram – B8 models
- Network bus topology – B8 models
- Function diagram – D4 and C7 models
- Network bus topology – D4 and C7 models
- All-wheel drive control unit J492
- Service
- Guided functions
- Other notes and information
- Overview of repair operations
Language: English
Format: PDF
Pages: 52
Self Study Program 476 – Rear axle final drive unit 0BF+0BE– Sports differential
