Quote Originally Posted by Frosty View Post
I was thinking that ther might be some slip in the auto? Why would the diff on the auto be 2.78 and a manual in the same model be 3.36?
Fair points. The speedo drive is always on the output shaft of any box. Any slip would be in the converter, which would explain why you get a slight flash in rpm when you start to accelerate from an already steady speed in top gear. In a trimatic for example, the band is completely disengaged, the 2nd and 3rd clutch packs are buttoned down driving the output shaft at the same speed as the input shaft (otherwise there would be no engine braking on decell either). The diff ratio issue would be more to do with first gear start-off in a manual (think hill start and trying to reverse with too tall a diff ratio) - or she would shag the clutch quick smart.