I never understood how you can push start a '57 -'58 Oldsmobile with an automatic ( Hydramatic ) , yet you cant push start a 1959 or 1960 Oldsmobile with the same transmission. Yet I have swapped '57 - '60 Hydramatics and they all seemed the same to me. What is so different about the pre '59 automatics? I was just curious

 

It has something to do with the rear pump on the earlier transmissions.

 

In real Hydros ('40 to '56) the driveshaft turns the rear pump, builds pressure, and actuates both bands, which puts the trans into first gear and turns the engine. Jetaways will work in a similar fashion, as long as they have rear pumps.

Norm