The Stovebolt Site Forums The Shop Area Engine Shop 54/55 1st Hydromatics

Who is familiar with the 54 and 55 1st series hydromatic transmisions?

I have a 53 Hydramatic, what are you trying to find out ?

I havbe two hydramatics.One is from a chevy, one is from a GMC.How much are they used?
How does it work in your truck?

When I was more of a rube than I now am (5 years ago), I drove from NY to MO to buy a 1954 Hydramatic transmission out of a '54 Chevy 1/2 ton. This is the first year for an automatic transmission in a Chevy truck. I understand that the '53 GMC was the first year for an automatic in a GMC truck.

The '54 1/2 ton Chevy Hydramatic is set up for an enclosed driveshaft AND the driveshaft is different than the enclosed driveshaft for a manual transmission (about 4 to 5 inches shorter). AND, I understand the engine and hydramatic transmission were matched at the factory. So, it would be a good idea to buy all three - no, it is a necessity.

Dumb luck was on my side - the engine and rear end were thrown in for free when I bought the Hydramatic (as was the front axel and steering box). Not a bad deal. On top of my good/dumb luck, it was an interesting and enjoyable drive (around 2,200 miles in 2 1/2 days).

Be sure you get the shift linkage, push button from the dash (to engage the special starter), starter with solenoid, frame crossbar (to support the rear of the transmission), the accelerator pedal and transmission cover for the cab floor. Also, be sure to get the shift indicator that goes on the steering column (it is cute and it is rare) and check to see if the mounting holes for the indicater are different than for a 3-speed (if they are, get the steering column). The brake master cylinder is unique to the1/2 ton Hydramatic and my Factory Assemblty Manual shows that the brake lines are routed differently.

Gee, I guess I really was a rube. Maybe I should have purchased the whole truck (which was not for sale at the time).

Am I right to think that the '55 first series 1/2 ton Hydramatic has an open driveshaft?

Does anyone have a 1954 1/2 ton Hydramatic cab and frame for sale (with or without the drivetrain)?

I have been told that this cast-iron 4-speed automatic transmission (which is quite heavy) was quite reliable.

53 4 me, how do you like your Hydramatic? Does it shift smoothly? Is it quiet? Has it ever been rebuilt?

Mechainiac, do you have the cab/frame for your Hydramatics?

Tim

i have a hydromatic in my 55 1st chevy and it did great i changed to a 10 bolt with 2.73 ratio and that worked good too interstate speeds of 70 no problem then it died one morning on the way to work and the estimates i have to rebuild it are around 1000.oo <>1500.oo so its sitting here in the yard i boubht a 57 hardtop belair last week and am going to sell the truck the car is better suiyed for the family yes the 55 1st has open drive line did not have to modify shaft for 10 bolt

[ 11-24-2001: Message edited by: pte359 ]

The Hydramatic in my 53 GMC works great. I have only owned the truck for two years. I took the side and bottom pans to replace the gaskets, everything inside looked nice and clean so I am assuming it has been rebuilt at some point.

As tclederman mentioned above, there are a few differences that are peculiar to the Hydramatic trucks. My block and bell housing both have the same number stamped on them. They were machined at the factory to be a matched pair. There is no foot starter but a starter button over the headlight switch and a solenoid on the starter. The gas pedal linkage is connected to a kickdown for the transmission. Also the carb is turned ninety degrees on the mainfold from a standard tranny model to accomodate the changes in the linkage. The wiring harness includes a neutral safety switch to keep the truck from starting in any gear except nuetral.

The Hydramatic shifts nicely and runs great behind the 228 GMC motor. I have the 3:55 Patricks gears so the truck cruises nicely at 55 - 60 mph.

It is always an eye catcher at truck shows. Many people were not aware that these early model trucks were factory equipped with the Hydramatic..

[ 11-24-2001: Message edited by: 53 4 me ]

Yes, I have several parts for the hydromatic trucks.I have both chevy and GMC cabs.The GMC has part of the frame,but it was cut off just behind the cab.
Contact me.

What years were the Hydromatics used in trucks??
Up to 62 possibly?

I see where this is going!

Mechainiac, I had a 62 GMC panel truck with a 305 V-6 with a hydromatic I,m not a hundred percent sure but I think it was the last year. It was one shifting muther!!! shifted 3 times before 40 MPH. Thank's Mick Inniss

[ 11-28-2001: Message edited by: mick inniss ]

I know the engine to bel-housing bolt pattern changed in 63.
I am pretty sure these will fit all the way to 62.
I have been told that they are nearly indestructable trannys.these two are both good units with linkage to boot!!!