All-Trac

All-Trac was a trademarked name used by Toyota for a full-time four-wheel drive system. It was featured on several Toyota models from the mid-1980s through the early 1990s, primarily on their passenger car lines. The All-Trac system was designed to provide enhanced traction and handling in various road conditions, including snow, ice, and wet surfaces.

The system typically employed a viscous coupling center differential to distribute torque between the front and rear axles. This type of differential allows for a variable torque split depending on the amount of wheel slip detected between the front and rear. Under normal driving conditions, the torque split was often near 50/50, but could shift as needed to maintain traction.

All-Trac should be distinguished from more traditional four-wheel drive systems often found on trucks and SUVs, which typically require manual engagement and disengagement and are intended for more serious off-road use. All-Trac was designed for on-road performance and improved all-weather capability.

Some notable Toyota models that featured the All-Trac system include:

• Toyota Camry All-Trac
• Toyota Celica All-Trac Turbo (also known as the Celica GT-Four in some markets)
• Toyota Corolla All-Trac Wagon