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Hydra-Matic tranny history
argent
Member Posts: 176
in Oldsmobile
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.
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.
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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?
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.
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.
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.
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!
Uphill.
In the snow.
With no shoes...
I didn't think they had invented shoes yet when you were born.
Did you have indoor plumbing?
Well, less'n of course you don't got no door on it...
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.
So how can I go about getting a copy of your trans history, Argent?
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.
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.
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).