The Stovebolt Site Forums The Shop Area Driveline 1954 Dual Range Hydramatic

I have a Hydramatic that came with the '54 GMC 302
They will eventually go back into the truck.
First things first, rebuild the engine.
Apparently the transmission was working fine when it was parked decades ago.
Thinking ahead when the engine is running I will install the transmission and test run before I install.
This is the heavy duty version, as is it has coolant lines
Not not had any experience with these transmissions.
So think ahead, at the very least it’s will likely need seals and gaskets .
Who is the supplier for these transmissions, gaskets, seals and tech info?

Dave

Northwest Transmission and Fatsco will have virtually everything you need for these transmissions.

Automatic transmission parts for all makes and models including Hydramatic and Jetaway

Fatsco Transmission Parts
337 ChangeBridge Road
PO Box 635
Pine Brook, NJ 07058
(973)227-2487 or (800) 524-0485
http://www.fatsco.com/index.htm


Transmission parts for Hydramatic, etc

Northwest Transmission Parts
13500 US Route 62
Winchester, Ohio 45697
937-442-2811
http://99.152.162.116/nwtparts/

Also Dave Edwards for parts. Years ago he loaned out the special tools you will need with a hefty deposit from you. Don't know if he still does.

Dual range HydraMatic is a joy when it is working and set up properly, but a PITA when it isn't. Rolls-Royce used them until 1966. I loved the one in my '57 GMC.

I knew there was a third one I forgot. Yes, Dave Edwards has everything for Hydramatics.

Automatic Transmission Parts, 40s –60s, rebuild kits

David Edwards
56 Dale Street, Dept. A
Needham Heights, MA 02494-1218
781-449-2065
http://www.autotran.us/

Check out the WW II Stuart light tank. It was powered by two Cadillac flathead V8 engines- - - - -with Hydra-Matic transmissions. Back in the 1950s my Father's only competitor in Nashville at building Hydra-Matics was a former US Army tank mechanic.
Jerry

Thanks for the info ! Just what I am looking for.
I never rebuilt an automatic transmission, hoping I don’t have to

The Dual Range Hydra-Matic can be a mechanic's nightmare to rebuild unless you have a shop full of special tools and lots of experience. Engines and transmissions were mated at the factory with very close runout tolerances, and unless the engine block, bell housing, and transmission stayed together, it was prone to failure due to misalignment. Offset alignment dowel pins were available back then to correct for runout errors if an engine block and transmission had to be force-matched during field repairs.
Jerry

I agree with Jerry about the mechanic's nightmare. There are a bunch of special tools just for maintenance type work and many more for tear-down and rebuild. Not an automatic to cut your teeth on.

There was also a 283 Chevy V8 with HydraMatic combo in a US Army tracked vehicle in the early/mid 1960s. M-114?

I have a 55.2 service manual that includes a section on the HydraMatic. As a comparison of the complexity, the 3 speed overdrive, the most complicated manual transmission gets 15 pages. The HydraMatic gets 98 pages. Here's a page showing the required special tools.

The Hydra-Matic was one of the most "over-engineered" transmissions I've ever worked on. For instance, it has two hydraulic pressure pumps, one driven by the engine, and another that's connected to the output shaft. Theoretically, that was done so hydraulic pressure to apply the clutches and bands could be developed by pushing the vehicle above 30 MPH- - - - -in case of a dead battery. However, there's an additional advantage- - - - -above certain vehicle speeds, the rear pump generates enough fluid volume that the variable-displacement front pump moves "over center" and acts as a pressure relief for the rear pump- - - - -effectively taking the load of generating hydraulic pressure in the transmission off the engine. There's a good reason Rolls-Royce licensed the production of Hydra-Matic transmissions for their own vehicles.
Jerry

Amazing how you have documented and shared the rebuild process. Thanks Tim!

As a lowly E3 autopilot tech/newlywed living in Cordell Oklahoma in early 1968 I had a '59 Chevy 283/Powerglide that didn't want to turn over fast enough to start when the temperature got down to 10 degrees or so. My "fix" for the problem was to park the car in the driveway nose out (down hill) the night before. Turn on the key, put it in low, let it roll out of the driveway and then turn right continuing downhill for a short distance. The rear pump wouldn't quite get the job done in that short distance so I rigged a bypass switch for the neutral safety switch so I could engage the starter while I reached "terminal velocity" of about 20 MPH. Started every time with the bump from the rear pump.

My '56 Cadillac's owner's manual actually states the car can be roll started in the case of a dead battery. Push it in neutral and then pop it into drive.

Good luck pushing that 5000 lb tank at the A pillar by yourself!

It's the first time I heard of an automatic transmission being able to be bump started like a manual transmission.

Had a automatic transmission in my straight eight 1950 Pontiac when I was 17. I remember having to get a push to get it started. Many years and beers ago.

My '61 Pontiac Tempest with the Corvair derived two speed automatic transaxle would also gladly push start, it only needed maybe 12-15mph and the hill outside my house was more than enough.