Multitronic
A continuously variable transmission, in some Audi cars, that uses a chain instead of a belt.
Multitronic: Audi's chain-drive continuously variable transmission
Multitronic is a continuously variable transmission (CVT) that Audi deployed in front-wheel-drive models from the early 2000s onward. Unlike conventional step-gear automatics with fixed ratios, it shifts smoothly through an infinite number of gear ratios within a range, keeping the engine closer to its optimal operating point. The mechanical heart of Multitronic is a steel roller chain, running on two variable-diameter pulleys, where transmission ratio changes by altering pulley diameter hydraulically rather than by shifting between fixed gears.
The chain design sets Multitronic apart from belt-based CVTs used by other manufacturers. A steel chain can transmit higher torque than a rubber belt and tolerates greater contact pressures before slipping. This made it suitable for Audi's larger-displacement petrol engines, typically ranging from 2.0 to 3.2 liters in vehicles that received the transmission. The pulleys are hydraulically squeezed by solenoid-controlled actuators; oil pressure increases to narrow pulley spacing, which increases the roller chain diameter in contact with those pulleys, shifting toward higher gear ratios.
Service and failure modes
Multitronic systems have a reputation for durability problems, particularly chain stretch and pulley wear. The transmission depends on precise hydraulic pressure regulation; degraded transmission fluid or stuck solenoids lead to erratic ratio changes and shuddering. Chain replacement typically requires full transmission removal, making service expensive. Some owners report juddering during acceleration in lower gears, often traced to worn pulleys or fluctuating hydraulic pressure rather than catastrophic failure.
The name Multitronic reflects the continuous, multi-ratio characteristic of the transmission family; the term follows Audi's naming convention for this generation of CVTs. Audi phased out Multitronic in the late 2000s in favor of traditional torque-converter automatics and dual-clutch transmissions, which offered more linear performance feedback and simpler thermal management. Today Multitronic appears mainly in used-market vehicles and represents a technically ambitious but commercially discontinued approach to smoothness and efficiency in passenger cars.