Common problems with a Ford automatic overdrive transmission in stock form are a weak lockup input shaft and the tendency for the overdrive band to burn up. To improve the automatic overdrive, mechanics upgrade and harden the input shafts and upgrade the valve bodies.
When upgrading input shafts, mechanics typically use parts made from billet or chromium-molybdenum alloy. To control overdrive, they may use an electric solenoid. For some people, the automatic overdrive is a problem because its converter is locked mechanically, although others prefer it because the overdrive is not computer-controlled.
In standard form, the Ford automatic overdrive can accommodate about 250 feet-pounds of torque and 300 horsepower. Mechanics can modify the transmission to accommodate between 700 and 800 horsepower.