1958 cadillac transmission ?

[dnn1942]

   I used to drive my father-in-law 58 Cadillac, he liked having a choafer ... As I remeber it, on the road at  about 50 mph it seemed to go into a "overdrive". It slowly went into the final drive gear, felt simular to todays lockup torque converters. Did I remember this wrong? or was there  something differant in the ratio's used in 58. I do remember thatfirst was very low and would shift near 15 mph at full throttle. This car also got 20 MPG on the road.
    Would like to hear comment on my experiance ( or my rememberance of it)

    Regards
     Dave
   

[boomosby]

 i am not sure the specfic ratios for teh 58 model year, but i know that the hydramtic/jetaway design the the 331,365,390 engine block uses is a "OD" tranny. i am not sure if they called it overdrive or not but it does have a 4th gear for sure! you are not mistaken. i have 4 60s, and each one of them gets grt gas mileage on teh highway, between 17 -22. i have a 58 fleet with airide that i wil be orking on sooon. i can give you a more accuarte description then.

[Roger Zimmermann]

The 4th speed is not OD, the ratio is 1:1. Due to the fact that there is a fluid coupling and not a torque converter on the Hydramatic first and second generation , it was necessary to have 4 speed.

Roger

[The Tassie Devil(le)]

...... but i know that the hydramtic/jetaway design the the 331,365,390 engine block uses is a "OD" tranny. i am not sure if they called it overdrive or not but it does have a 4th gear for sure! you are not mistaken. i have 4 60s, and each one of them gets grt gas mileage on teh highway, between 17 -22.   

The only reason you are getting good fuel mileage is because your engine if fuel efficient, due to its' high compression, plus, the Speedo is reading fast, and therefore the Odometer is turning over faster, registering a higher distance traveled against actual distance traveled.

Plus, you don't have to put the gas pedal down as far to move off from a stop.

Bruce