The NAG1 automatic transmission is an electronically controlled 5-speed transmission with a lock-up clutch in the torque converter. The ratios for the gear stages are obtained by 3 planetary gear sets. Fifth gear is designed as an overdrive with a high speed ratio.
NAG1 identifies a family of transmissions and means “N”ew “A”utomatic “G”earbox, generation 1. Other names associated with the NAG1 family of transmissions depend on the transmission being used in a specific vehicle. Some examples are W5A300, W5A380, and W5A580. The name can be interpreted as follows:
- W = Transmission using a hydraulic torque converter.
- 5 = 5 forward gears.
- A = Automatic Transmission.
- 580 = Maximum input torque capacity in Newton meters (428 ft-lbs).
The gears are actuated electronically/hydraulically. The gears are shifted by means of an appropriate combination of three multi-disc holding clutches, three multi-disc driving clutches, and two freewheeling clutches. Electronic transmission control enables precise adaptation of pressures to the respective operating conditions and to the engine output during the shift phase which results in a significant improvement in shift quality. Furthermore, it offers the advantage of a flexible adaptation to various vehicle and engines.
Basically, the automatic transmission with electronic control offers the following advantages:
- Reduces fuel consumption.
- Improved shift comfort.
- More favorable step-up through the five gears.
- Increased service life and reliability.
- Lower maintenance costs.
The transmission can be generically identified visually by the presence of a round 13-way connector located near the front corner of the transmission oil pan, on the right side. Specific transmission information can be found stamped into a pad on the left side of the transmission, above the oil pan rail.