I have a 1957 Pontiac with a Stratoflight and the transmission is close to dying. Is a 1956 Olds Jetaway the same trans? I can get a really good price on a completely rebuilt one, but it doesn't do me any good if it doesn't work. It appears that the pan gasket configuration is somewhat different.
Are you sure the ‘56 Olds tranny is a Jetaway ? In ‘56, Olds used two different Hydramatics, depending on model. One was the older dual-range hydro, the other the Jetaway. Ray
The 32nd Hollander book says the 1956 Olds JHM trans fits the 1956/57 Pontiac by changing just the converter and converter housing. When changing the converter housing make sure you change the rectangular o'ring between them. The 1956 JHM's had a major weak point, the 4 lug driven torus, but most broke and have been changed by now, hopefully the 1956 one was changed. The only reason the pan could look different if one was a 1956-59 trans (15 bolt holes) and the other one is a 1960 (or up trans 14 bolt holes). Dave
"Positive, it has park position." Are you saying the 1956 trans is in the car and it has a "P" on the quadrant or do you mean because you can lock up the output shaft that it must have the Jetaway "Park". All 1956 and earlier regular Hydramatics have a Park position which is Reverse when the engine is turned off. Turn off the engine, pull into Reverse, and the Parking Pawl drops into place. The regular early Hydramatics all have a 12 bolt pan plus a side pan. Dave
Thanks for the excellent information. I should have just said that it has a 15 bolt pan gasket. It's not in the car, but the shift sequence still indicated Jetaway. I'm not sure what you mean by the term "converter" for this vintage transmission. I associate converter with torque converter. I need to speak to the person that rebuilt it to ask about the torus. He's about 80, and has been doing it for a long time, but longevity doesn't always mean expertise. We'll see if he knows the details of what you just told me. I just can't find anyone qualified to do what I need. Do you rebuild these? Most of my friends told me to switch to a turbo 400. Expensive, and only a 3 speed.
It has a split torque converter held together by 12 or 24 (very early models) studs. You must remove the 12 nuts and separate the converter to be able to remove it (snap rings). After removing the converter you than can separate the housing by unbolting it. Put a new o'ring in the housing you are going to use and bolt it to the trans. Then reassemble the TC to the input shafts with the snap rings then install the large, aprox 12" dia o'ring on the cover and bolt it back together. It is now ready to be attached to the engine. Good luck, Dave A guy I have known over 35 years, (Steve) Peluso Precision Automotive in Mendon, MA rebuilds them 508-478-8900 By the way, nothing is cheap today!
Thanks again! You're right, of course, nothing is cheap today - my wife proves that to me all of the time. I really wasn't trying to get away cheap, but the conversion is about $1000. more than what I would have to pay the local guy to rebuild mine. He only wants $1000. for the Olds trans, which would save me $500., but I'm not going to buy it to save the money if it creates too many headaches. What's your opinion on converting to a TH350 or 400?
Any of the later TurboHydramatics would be a good replacement for your old hydro. The fact that the 350/400 are three speed is no detriment regarding performance. The reason being, the TH trannies have a torque converter rather than the earlier hydro’s fluid coupling. The difference being, as the name implies, the torque converter multiplies engine torque initially, whereas the fluid coupling does not increase torque.....hence the need for a lower 1st gear. Also, the later TH trannies shift a bit quicker than an unmodified dual range hydro. Getting the newer trans repaired is easy peasy compared to the old hydro. Unless originality is a prime consideration, adapting the newer trans is a better deal......in my opinion. Ray
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