All-Trac is a permanent four-wheel drive system installed on certain Toyota vehicles between the years 1988 and 2000. It was developed by the Japanese car manufacturer Toyota Motor Corporation in 1986 and was originally called “GT-Four”. It was considered revolutionary at the time because it offered a center locking differential that had previously rarely been seen on passenger cars.
The All-Trac Design and how it works
In the early versions of the system, the output torque from the gearbox was fed to the center differential, which was built into the front differential. Then the power could be evenly distributed to the axles. The traction of the wheels has consequently been improved on all surfaces. There was also the option of manually shifting the transfer case with the “Center Diff. Lock” button that could be found in the interior. After pressing the button, the axles were firmly connected and the drive shafts of the front and rear differentials rotated at the same speed.
Later, a viscous coupling replaced the center differential.
Vehicles equipped with the All-Trac-System
| Model | Years of manufacture | Equipment variants that include the system | Displacement (l) | Engine power (hp) |
| Camry V20 | 1988–1991 | DX, LE | 2 | 82–140 |
| Corolla E90 | 1988– 1992 | Standard and SR5 | 1.6 | 95-125 |
| Previa XR10 | 1990–1999 | DX, LE | 2.4 | 135 |
| Celica А60 | 1988–1993 | Default | 2 | 203–205 |
| RAV4 XA10 | 2 | 119–129 |