whats the difference between an overdrive and direct drive tranny?
In a direct drive tranny the highest gear ratio in the tranny is 1 to 1. That means that the engine crankshaft is mechanically coupled directly to the transmission output shaft and driving at the same speed. In an overdrive tranny the highest gear ratio is higher than 1 to 1 (usually somewhere around 0.85 to 1). Most new standard transmissions 4th gear is direct and 5th is overdrive. This is not always the case but is generally true. In automatic trannys 3rd gear is usually direct and 4th is usually overdrive; again this is not always true. If you have an old automatic like a TH350, TH400, C4, C6, TF626, TF727, these are all 3 speed non overdrive transmissions. A 2 speed power glide is a non overdrive transmission. If you know what year and type of tranny you have post it and someone can tell you.
