The Stovebolt Site Forums The Shop Area Engine Shop 1956 Hyrda Matic band adjustment

I just bought an old Oldsmobile Super 88 has the 4 speed Hydra-matic inside. I dropped the transmission oil pan to clean out the 50 years of Gunk and clean the filter. I noticed the rear band has almost a quarter inch (3/8) of play! Is the band adjustable, and should it have that much freeplay in it? I bought the car without ever test driving it because the fuel pump is out. The previous owner said he had to let it warm up some, before the trans would engage. The transmission oil didnt smell burned but looked like the oil was breaking down back into a dead dinosaur, the filters corners were clogged so I've used an air compressor to blow the clumps out of the filter. Once auto zone finally gets me my new fuel pump I can elaborate more on the trans symptoms. I just want to know if I should be prepared for a trans overhaul, or a possible swap for a newer modern trans, or hopefully just a little adjustment on the bands.

Thank you all for any Help in Advance

In 56 they came out with the new Jetaway trans. If it has that one I don't know much about it. The old style 4 speed automatics had band adjustments on the side of the case. You could get a good book that will tell how to adjust them. I can look at some old manuals tomorrow when I get to the shop.

Hy ApacheAtkins, could you take a picture of the tranny oil pan, or measure it, describe the shape and the number of holes. In Canada I don't think Oldsmobile went to the Jetaway until 57, but Icould be wrong about that.

I have several 50s GM (Chevrolet and GMC truck) Hydra-Matic manuals and would be pleased to scan and mail instructions, if some one can help in determining if what you have is the same as was used in a truck.

I'd appreciate it very much. My email is [email protected] From what I've been researching they did different variations of the Hydra-Matic for the different branches of GMC.

I couldnt get very good pictures they really crammed it in there along with the V-8 you can tell this car was designed for a 6 cylinder not the Rocket 88. The Pan has 15 Holes and measures 15 3/4'' X 12 5/8''.

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And if you want to mail them I'll gladly send you the cost in postage.

Hy ApacheAtkins, those dimensions and number of holes say Hydramatic, not Jetaway, hope that helps.

Bobb,

What information might help to identify the year? And, if it might be the same as a same year GMC truck Hydra-Matic?

Thanks,

The Dual range Hydra-Matic did not have a Park position on the shift quadrant- - - - -Reverse served as park when the engine was not running. It looks like you have a "Controlled Coupling" hydra-matic, which was erroneously called Jetaway by some people. I believe the last Dual range was installed in 1955 Olds and Pontiac cars. Chevy trucks never ran a controlled coupling transmission.
Jerry

Hy guys, Hotrod Lincoln is correct, in that no two coupling Hydramatics were ever used in trucks. the truck Hydramatic oil pan has 12 holes, and is 13 3/8" X 10 3/16", the two coupling Hydramatic oil pan has 15 holes and is 15 1/2" X 12 5/16". Incidently there were two different Hydramatics offered in 1956 Oldsmobiles, the type "R" which is the older dual range Hydramatic [same as the transmission used in the truck], and the type "O" which is the two coupling Hydramatic used up to 1959. I haven't been able to locate a detailed enough description of the transmission in question, to say whether the "overunning band" is adjustable or not, but I will keep looking.

Well I got the fuel pump in and topped the transmission off with fluid. Unfortunately my fears were realized.The transmission is failing to move the car. The bands must be worn down from 54 years of driving. The engine barely goes under any load when I place it in gear.I Hooked the eingine up to the tachometer it drops about 50 RPM if that when in gear. Tomorrow I'm going to look for an access hole for topping off the torque converter I'm thinking maybe the trans fluid in there is as bad as what was in the pan. I agree with Hot Rod Lincoln from what I've researched its definitely the Jetway but I've had very little luck in finding any shop manuals on the transmission. The plus side is that it runs much smoother than any straight six I've owned. But I still favor the simplicity of an Inline 6.