Hydramatic performance

dave11

Wondering if there are any hydramatic experts on line that answer a few questions, or dispell rumours.

 I understand that the hydramatic transmission was introduced in 1942? and was used during WW2 in military tanks.

 I have also heard a rumour that when this transmission was offered in the new Oldsmobile rocket in 48 it was quite a performer. In fact my father used to tell stories of back in the day "they" used to say an Oldsmobile driver would tape a $10.00 bill on the dash, mash the throttle to the floor, if you the passenger, could grab the bill before the car reached 20 mph, you could have the bill....who knows ,...this may well be an urban legend?

Another Hydramatic rumour I've heard is that by the time these transmission were used in Hudsons the shift pattern was changed so that first gear was only used to get the car rolling , almost imediately it would shift into second gear,...apparently this was done to tone down the acceleration which was a considered bit intimidating for the average car buyer.

Dave Eddie

snowshoe90aolcom

Dave, I'm no expert but I do own and drive two Hydra-matics...one in a '51 Hudson and the other in a "54 Cadillac. Cadillac engineers were the ones who designed these transmissions and they were installed in Oldsmobiles to test them out....they didn't want the initial problems to show up in a Cadillac. The Hudson has the single range version and the Cadillac has the dual range version....the difference being you could shift the dual range to third and leave it there for better around town acceleration (and according to the manual, up to 70 mph). Both these transmissions have early shift points....about 4mph from first to second....7mph 2nd to 3rd depending on the throttle position. The Hudson will really jump if I step it down in first and will bark the tires as it shifts to 2nd.....the Cadillac is too heavy for me to try and squeel the tires. I have heard that they were used in tanks during the war and that they were mated to Packard engines. I tried the $20 bill on the dash and lost....to my wife.   Terry

Ric West IN

Many ww2 tanks were Cadillac flat head V-8 powered with hydramatic.   

Fred

lostmind

I think 1939 Olds was first with hydro

RonS

Dave, the Hydromatic was first offered by GM in the 1940 Oldsmobile, then in 1941 in Cadillac. It was a single Dr   2 speed transmission with two ranges High and Low, and a mechanical reverse. That gave the sense of a 4 speed unit. But, the unit had N D L & R. There was no way to hold 3rd ( actually Low/high range). The unit would start in 1st (low/low) go to second(high/low), then 3rd, then 4th( high/high) .   It was indeed used in WW2 tanks. I believe there were 2 torque converters used for each track. They were the same until 1952, when the Dual Range Hydros were offered in all cars using them. Those cars were Cadillac, Olds, Pontiac, Hudson, Nash, Kaiser, Willys, & Rolls Royce. Now the driver can leave the trans in D-3(nice for city drives) or D-4. but now, when in  Low  it stayed in low and did not upshift to second as single range. The '51 Hudson only had a single range Hydro , albeit with a hydraulic reverse. That permitted the driver to shift back & forth from L or D into reverse without a completely stopping, necessary to rock the car in snow or sand. Confused yet? Ask about Fluid Drive. Performance was negatively affected as well as gas mileage, in all automatics or semi- automatics of the time. The Borg/Warner units in Ford & Rambler( later) started in second in D-2  unless those units were placed in L  (Ex Fordomatic) and shifted manually to D or D1 Cruiseomatic and Flashomatic . An educational course was needed to properly operate these cars back then. BTW the Rocket was in the 49s. 303 cubes... way faster with a manual shift.

Park_W

To be technically accurate . . . Hydramatics (note spelling) of the forties and early/mid fifties did not have torque converters, they had "fluid couplings."  There's quite a difference.  A torque converter produces significantly more hp to the drive wheels when you're stopped and punch the throttle.  A fluid coupling is essentially a "fluid clutch."

It's my understanding that the Dual-Range Hydramatics are pretty much the same as the preceding ones except for the control valve changes that allowed one to stay in 3rd around town.  The change was driven by the adoption by most companies of 3.07 or similar rear end gearing, for better fuel mileage and lower rpm at higher cruising speeds.  With the higher gearing, if you didn't have the ability to keep it in third, you'd often find yourself at 30 mph in 4th gear, wanting to accelerate but in an awkward gear.  Some of the Hydramatics had a "part-throttle kickdown" feature to help work this problem.

dave11

Dave, I'm no expert but I do own and drive two Hydra-matics...one in a '51 Hudson and the other in a "54 Cadillac. Cadillac engineers were the ones who designed these transmissions and they were installed in Oldsmobiles to test them out....they didn't want the initial problems to show up in a Cadillac. The Hudson has the single range version and the Cadillac has the dual range version....the difference being you could shift the dual range to third and leave it there for better around town acceleration (and according to the manual, up to 70 mph). Both these transmissions have early shift points....about 4mph from first to second....7mph 2nd to 3rd depending on the throttle position. The Hudson will really jump if I step it down in first and will bark the tires as it shifts to 2nd.....the Cadillac is too heavy for me to try and squeel the tires. I have heard that they were used in tanks during the war and that they were mated to Packard engines. I tried the $20 bill on the dash and lost....to my wife.   Terry

dave11

 I have a wife like that as well

Park_W

I can answer Dave's question about the "Rocket 88s" being hot performers.  Starting with their first year, '49, and continuing for three or four years, they were indeed the car to beat in the local traffic-light drags..  A very well-designed and reasonably light weight engine in the Chevy body. The Caddy engine was actually a little lighter, and more "cubes," the same for the Chrysler hemi when it arrived in '51, but both these cars were significantly heaver than the Olds 88.  And the Chrysler suffered from a non-competitive transmission early on.  So if you could beat an "88," you were doing very well.

SuperDave

Park,

I did outrun a 53 Olds (HydraMatic) with my 51 Hornet four door three speed (no O.D,).probably about 1970. Both cars were four doors and light blue. We met at a traffic light and we exchanged glances, thumbs up and a nod. He was holding the brake and had the engine well above an idle.. Remember how the olds rear end would raise up when the springs started to wind up? Light turned green and I beat him to the next light with much room to spare. He was determined to beat me next time and jumped the light by 1/2 a car length. I caught him in second gear a half block away when disaster reared it'd head. My left front motor mount separated.  Throttle linkage went past center and locked wide open. Clutch linkage came apart and the pedal fell to the floor. Can't pull it out of gear!!! With both feet on the brake pedal I shut the engine off and coasted into a parking lot.. Never saw the Olds again. must have been visiting from out of town.

RL Chilton

That's a great story, Dave!  Did you have to clean the seat, too??!

Park_W

The '49 Olds Hydramatic was the preferred one by "rodders."  Although its downshifts weren't as smooth as in subsequent years, the upshifts were very solid, thus the attraction to car guys.  Near the end of my relationship with my '38H sedan in '54, I put an all chromed-up '49 Olds engine and Hydramatic in it.  As a nineteen year old USAF 1-striper, I didn't have the means to do anything in the way of rear end gearing, so ran it with the original 4.11.  Got away from a start very quickly, but was maxed out at 90 mph.  Wish I'd gotten a pic of that engine . . . literally everything that wasn't cast iron was chromed (bought it that way).