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Hydra-Matic tranny history

I was reading through the Oldsmobile FAQ at www.442.com, and saw that their section on automatic transmissions had a lot of missing pieces on the early (1940-1964) Hydra-Matic. For some bizarre reason I went on this odd quest to compile a history of the old HM -- which is historically notable as the first commercially mass-produced, fully automatic transmission. I was going to send it to David Brown, the Olds FAQ compiler, but e-mails to him bounced as undeliverable.

I figured since I went to the trouble of putting this together, I ought to get it out on the web to get corrections and clarifications, and eventually have it added to the FAQ for the reference of other auto history nuts.

Anybody out there interested in taking a look at it? It's an RTF document, about five pages and a bit over 2,000 words. I'd be happy to get updates or corrections.

Comments

  • argentargent Posts: 176
    RTF = Rich Text Format. What that means is that it's a "generic" word processing document -- it's got proper line breaks and basic formating (unlike pure text documents), but it can be read by any word processing program for Mac or PC. (It was created in Word, but RTFs are much easier for Mac users to open -- Word for Mac is weirdly fussy about opening Word for Windows documents for some reason.)
  • andre1969andre1969 Posts: 21,902
    ...to read up on it. Don't know if I could add anything, but I'm just thinking as a learning experience for me!

    One thing I'm wondering, what exactly is a TH-200-R4? Is it basically just an overdrive version of that flimsy little TH200 that made GM infamous in the '70's? I found out that my grandmother's '85 LeSabre had that tranny...I just thought it would have something a little sturdier! It was a good tranny though; we got rid of that car with 157,000 miles, and the tranny was still fine. My mom's old '86 Monte, I guess had the same tranny, and it had about 192,000 miles on it when I totaled it.

    I was just kinda surprised that these trannies lasted so long, if they were indeed based on that TH200.

    Also, what kind of tranny would my '85 Siverado have? It's a 1/2 ton truck, 3-speed automatic, 305-4bbl V-8. Would that be the TH350, or something newer?
  • wq59bwq59b Posts: 61
    I'd also be interested in reading it, but what is an RTF document? What program would I need to open it?
  • andre1969andre1969 Posts: 21,902
    ...I think. I think my computer at work can open it, but I'm not sure. Microsoft Word might be able to open it, but I dunno for sure.
  • argentargent Posts: 176
    I'd guess an '85 Silverado 305 probably has a TH350, unless it had optional heavy-duty transmission, in which case I think that meant TH400.

    The TH200-4R is indeed the old light-duty TH200 with an integral overdrive and lockup torque converter. The reason for the light-duty transmission was that it weighed less, cost less, and consumed less power than the big TH400 -- the less-beefy innards made it less durable, especially if the engine was souped up, but had less mass and inertia, so it got more of the engine's power to the ground.
  • Mr_ShiftrightMr_Shiftright CaliforniaPosts: 44,547
  • carnut4carnut4 Posts: 574
    the original Hydramatic could be called one of the best automatics ever, since it was bought from GM and offered in so many different makes [Lincoln, Hudson, etc, etc,] and did its time in tanks in WWII. My Dad had a 57 Pontiac with the "strato-flight" dual turbine version of it. I got my license, and learned how to burn rubber in that car. The 55 Pontiac I have now has the simpler version of the Hydramatic, with no park position. You put it in reverse for park. THe shift points are also a lot harsher than the later Hydramatics that came out in 1956.
    From what I've heard, all those hydramatics were pretty strong transmissions. Funny how Olds and GM could pioneer and build a tranny like that and then years later stick the lowly THM200 in its fullsize cars. Oh-not to mention the "Roto-hydramatic" we've already talked about elsewhere in this forum. It was a cost thing, just like everything else.
    GM seems to be good at finding ways to save money on production, and then passing on the result [one way or another] to the buyer.
    Personally, I've always thought the original Chrysler Torqueflite was right up there with the Hydramatics deserving honorable mention.
  • argentargent Posts: 176
    The Hydra-Matic was tough and efficient (they did use a lot of them in military vehicles both in WW2 and Korea), a lot more so than the early Buick and Chevy torque converter transmissions. The Dynaflow and Powerglide were smoother, but they were syrupy and slow. The Dynaflow (and the Powerglide before 1953) didn't even shift in normal driving. You started out in direct drive and took off on the converter multiplication. You had to manually select Low and shift up to Drive to get 1st gear, and doing that too much wore out the bands.
     
    The problem GM had with the Hydra-Matic is that it wasn't particularly smooth. It shifted with a surge and a clunk, especially if it wasn't in perfect shape. They kept revising it to make it smoother (leading up to the dual-coupling system in '56), but that also made it more complex and more expensive to build, Chrysler's Torqueflite was a better compromise. With three speeds and a torque converter, it actually had better off-the-line torque multiplication, but with less drop in engine speed between shifts (and thus smoother shifting), and it was less expensive and less bulky (Torqueflite weighed around 70 pounds less than the four-speed Hydra-Matic). That's why GM ultimately went to the THM in '64-'65.

    Interestingly, I read that almost all the three speed/torque converter automatics used in America by the sixties were based on an arrangement designed by the same engineer. Evidently Howard Simpson had worked out the optimal setup, and so thoroughly blanketed it with patents in the early 50s, that each of the major automakers ended up paying royalties to his estate for their automatic transmissions.
  • kinleykinley Posts: 854
    start the car under compression. At least in 1950, the Hydramatic could be started by being pushed to 40 mph and then dropping the selector lever into "Lo". Something about deleting the rear pump to make more interior room in the cabin stopped this feature. A Kettering engine, Hydramatic, with Power Steering in the Rocket 88 was "everything" in '52.
  • andre1969andre1969 Posts: 21,902
    Kinley, are you sure it was 40 mph? My '57 DeSoto also has that feature, but according to the owner's manual and everything else I read, you only had to get it up to around 10 mph. Seems kinda dangerous to have to push a car up to 40 to start it!

    I think you're right though, that the pump in the rear had something to do with it.

    Oh yeah, thanks for the file, Argent. Good reading, and very informative!
  • dgraves1dgraves1 Posts: 414
    40 mph? You need some damn fast guys pushing you.
  • andre1969andre1969 Posts: 21,902
    ...the idea was to get another car to push-start you. Let's try THAT with the bumpers they have on cars nowadays! I think even getting it up to 10 mph would be rough, unless you had a downhill slope or enough manpower.
  • wale_bate1wale_bate1 Posts: 1,986
    Oh hell, all y'all are wimps these days. Heck, we use to push 'em to 50.

    Uphill.

    In the snow.

    With no shoes...
  • rea98drea98d Posts: 982
    "With no shoes..."

    I didn't think they had invented shoes yet when you were born.

    Did you have indoor plumbing?
  • wale_bate1wale_bate1 Posts: 1,986
    Technically speaking, an outhouse is "indoors".

    Well, less'n of course you don't got no door on it...
    ;)
  • Mr_ShiftrightMr_Shiftright CaliforniaPosts: 44,547
    I recall the speed was about 30 mph, maybe 35.

    Oh, yeah, we would push 'em up to 40-50, wale is correct about that. Or tow them 25 miles on a piece of short rope. Roads were not so crowded in the 70s, and the few cops that were around were fairly blase, since nobody was carrying guns around. Also, no compulsory insurance, and the cars were pretty tough, if crude, back then. It was car lovers paradise on the cheap.

    MODERATOR

  • dgraves1dgraves1 Posts: 414
    Are you describing the '70s or the '20s? Doesn't sound like the '70s I remember. Where were you then, Shifty? In Montana?
  • wq59bwq59b Posts: 61
    All HydraMatics built after 1958 cannot be push-started because of -yes- no rear pump. But '58 and earlier HMs can be. For the Dual-Range HM, you turn on the ignition & shift into D between 30-35. For the earlier single coupling HM you turn the ignition on at 18-20 MPH and shift into D at 25.

    So how can I go about getting a copy of your trans history, Argent?
  • Mr_ShiftrightMr_Shiftright CaliforniaPosts: 44,547
    No, not Montana....New York City! No, really, you could get away with murder then when it came to messing with old cars anyway. Age of Benign Neglect.

    Being able to push an automatic trans. for a start in freezing winter weather was definitely a plus...although I'm amazed we didn't break something, doing that to a basically frozen driveline.

    MODERATOR

  • dgraves1dgraves1 Posts: 414
    No compulsory insurance in New York City in the '70s? That's where I was then, Shifty and you couldn't register your car until you proved you had insurance. And if you missed an insurance payment, the cops would show up at your house and take your plates. Believe me, I know this to be true.
    And the cops were anything but lackadaisical. But maybe a 17 year old kid in a hopped up Camaro with headers and glass packs gets a little more attention then he wants.
  • Mr_ShiftrightMr_Shiftright CaliforniaPosts: 44,547
    No, I don't remember NYC being tough at all. Chicago cops were a LOT meaner. You may be right about the insurance though, but it was very easy to get around every rule, even that one, at least the neighborhood I lived in. I used to drive without license plates a lot of the time, park on the sidewalk, fix cars in the street, and of course the notorious 40 mph automatic trans push--lol! We did a lot of street racing. There just weren't enough cops around to watch you all the time.

     Being such a gigantic place, I'm sure it was different everywhere you went. Like they say-- "Anything you say about New York is true".

    We were bad boys, but never hurt anybody (much).

    MODERATOR

  • argentargent Posts: 176
    I've been revising the history (now up to 3800 words - ack!), and I'd be happy to e-mail it to anybody who wants to take a look. There may be errors, because info on the old HM is sketchy these days and often contradictory -- that's part of what inspired this in the first place -- so corrections would be graciously appreciated. wq59b, thanks for the info on push-starting, which was more specific than I'd found before (I actually quoted you, if that's ok).
  • wq59bwq59b Posts: 61
    No problem. I would be interested and more than willing to contribute wherever I could; I'd return my comments & my sources of info and let you judge whether or not to use them. If you post your e-mail I'll contact you off-line with mine, if that's OK with you.
  • argentargent Posts: 176
    Anyone who would like a copy of the document in its current form can contact me at aaron@platinumstudios.com and I will forward it. It's still missing reference and bibliographic information, which I still have to compile.
This discussion has been closed.