Toyota AC60E / AC60F

Toyota's six-speed automatic for the body-on-frame vehicles — in the Fortuner and the Land Cruiser J300.

It replaced the A750F in the same role, and the pattern of failure follows the use rather than the design: these tow, idle in heat and run in low range, all of which put work through the torque converter rather than the gearbox.

So the recurring complaint is a shudder or a slip that appears when the vehicle is hot and loaded and disappears when it is not — the lock-up clutch, and a fluid-condition symptom first. On a towing vehicle the fluid decides whether it wears out at 100,000 km or 300,000, which makes an auxiliary cooler a preventative measure.

The AC60F is the four-wheel-drive version with a transfer case attached; mechanically the same gearbox, and the letter is the only record of the difference.

Fluid is Toyota's WS. As across the whole range, using the earlier Type IV produces a harsh cold engagement in a transmission that is fine.