The Stovebolt Site Forums The Shop Area Engine Shop GMC hydramatic ???

I have an oppurtunity to pick up a 56 GMC with a 316 (Pontiac) V-8 and a hydramatic transmission. I was just wondering what other engines that hydramatic would bolt to as the 316 is not running.

I would assume it would mate up to the 288, 347, 336 Pontiac/ GMC engines, how bout a SBC? 389?

The dual-range Hydramatic in that truck has a variety of bellhousings that bolt to the main transmission. You'll need the bellhousing that matches whatever engine you choose to make it fit. Hydramatics were also used in some non-GM cars such as Lincoln Continental, Nash, and several others. Of course, the mid-50's Pontiac, Cadillac, Oldsmobile, GMC, and Chevy trucks all used the Dual Range. I think the 389 Pontiac and the later model Olds and Caddy engines had a different bolt pattern for the Turbo 350 and 400 transmissions.
Jerry

Jerry,

I have a '54 Hydra-Matic Chevy truck and am interested is understanding H-M terminology. "Dual Range" Hydra-Matic is a term that has been discussed on this site and elsewhere, and the use seems unclear.

Here is a page that gives some information but it would nice to see a GM manual's explanation for dual range.

Here is another reference to a dual-range Hydra-Matic that refers to dual-range as the use of two-speed gear box together with the Hydra-Matic.

[img]http://www.futurliner.com/images/trans1.jpg[/img]

What is your understanding of the meaning "dual range" with respect the Hydra-Matic transmissions?

Thanks,
Tim

FYI for Tim

http://cgi.ebay.com/ebaymotors/Pont...nual_W0QQitemZ320052945004QQcmdZViewItem

Randy,

Thanks.

Tim

Jerry,

If I understand your post... A 55-59 chevy truck hydramatic bellhousing will mate to the gmc hydramatic and make it possible to swap a sbc where the pontiac engine was???

Hy bigbadswingdaddy and guys, Yes you are correct in your assumption about what Jerry told you, but you will have to buy / fabricate mounts for the front/side of the engine as the sbc used a different mount system than the Pontiac in the trucks, hope that helps.

Swing-D, it might be a bit more complicated than that, but you're basically correct. Things like the correct flywheel, engine mounts, etc. would have to be purchased or fabricated, but the old hydro was pretty adaptable. Finding one of those Chevy V-8 to Hydramatic bellhousings might be a challenge, as they weren't too plentiful when they were original equipment, and 50+ years have taken their toll on their numbers.

The term "Dual Range" actually applied to transmissions built in the 53-55 model years or so, when GM added a "Drive right" or "Super" shift lever position which prevented the 3-4 upshift from happening until about 65 MPH. It was intended to give better throttle response in traffic, etc. Earlier Hydramatics had a shift quadrant that included only neutral, drive, low, and reverse positions. Park was accomplished by placing the shift lever in reverse with the engine off, and a locking pin would engage the output shaft, locking the driveshaft. Transmission oil pressure would release the pin when Reverse was selected with the engine running, providing a reverse gear.

In 1956 the Controlled-Coupling Hydramatic was introduced, with a revised shift quadrant consisting of Park, Reverse, Neutral, Drive, Super, and Lo positions. This same basic shift quadrant was used through the Turbo 400, 350, and some other applications with various changes for some vehicles.
Jerry

Thanks all. I let this one slip by. I was looking to buy a 56 gmc...

I am in the process of gathering parts needed to take the hydramatic out of my 1954 GMC 100 and put in a standard shift 3 speed with overdrive. The hydra doesn't shift very well and I think it will give trouble, besides I like the o.d setup best of all combinations available for the AD trucks. As soon as I get all the stuff I will put the std. shift trans. in and will have a hydramatic for sale if anyone is interested.

chevman,

Be sure to post those parts in the Parts for Sale section of this site. Also, you might want to post in the Parts for Sale section of the oldGMCtrucks.com discussion board.

Parts to be careful to keep (if you will not be using them):

• Carburetor and accelerator linkage parts (linkage to the accelerator pedal and to the transmission). They are specific to the Hydra-Matic.
• Shift lever, indicator, and shifting mechanisms (all the way to the transmission).
• Cross-frame mount at the rear of the transmission (only used on Hydra-Matic trucks in 54/55).
• Torque-tube and rear end (it is shorter than the torque-tube used on manual transmission 1/2 ton trucks.
• Hood side-emblems.
• Transmission floor cover, if you do not need it - it is different than on non-Hydra-Matic trucks.
• Starter, and brake master cylinder - they are different than on non-Hydra-Matic trucks.

If Greg Hill sees this, he will most likely correct and add to this.

Some of the above parts you might still use, but, if you are not going to use them, keep them with the transmission.

Tim

Tim is right. Basically they changed everything so that the crossmembers unbolted and transmission could be removed from the bottom of the truck. That affected the brake line routing, starter is different due to electric start vs. the old foot stomper. Carb had auto choke where manual trans had a cable operated manual choke with a throttle cable also. GMC had different linkage, frames, and shift indicators than the Chevs did. Truth is, the GMC looks a little more substantial and the shift indicatpr is much nicer than the Chev version. In half ton trucks, GMC got hydramatic I think in 53 where chev waited until 54. Tim is being modest. You need to look at his website to get a feel for all of the information he has accumulated. I learned quite a bit out of neccesity by biting off a project that turned out to be bigger than I expected. All taht being said, I don't like to see any of those parts get away. As Tim also stated, there are many hydramatic owners on the oldgmctrucks site. There will be several people willing to help you out to keep an eye on where the old parts go. Good Luck, G.H.

chevman32: I sent you an email about my friend hunting a hydramatic....but your 54 will not work in his 1949....I don't think. Sorry.

If someone is interestedin a trade, I would include all the hydramatic parts in exchange for all the column shift parts. I have collected some of the stuff but still need some. I have both '54 and '55 first series stuff, both are open driveline setup, no torque tube. I'm not in a great hurry but would trade tomorrow if the necessary stuff is available. I also have a complete 1955 first series 248 engine that could go with the trans.

I have seen those trannies hooked to those honkin GMC V sixes. The 305 and 351 V6. As what I remember of those trannies, they were well built. I have a friend that has exactly the same year and model. His son has the auto and his is the manual trans both with the Pontiac 347 engine. And they both run real well. A nice trucks to have. Just thought I would throw in my 2 cents worth. Henry