[Bill Eveland]

Geez even with a 2.75 gear it would seem like alot.
M-20 2.52 x 4.30= 10.84
Hydro 3.97 x 2.75= 10.92
And have highway gears to boot.
I take it a 2:52 is the standard gear for a th-400 than ?

[PITTSBURGH 64]

The M-20 stands for wide ratio Muncie 4 speed.

The Turbo 400 has a 2.48 first and has torque converter, its a different animal. The hydro is more like a stick with an automatic clutch (fluid coupling) and has low gear ratios with a direct drive to get the car under way.
If you listen to the video, you can hear a little bit of tire scratch right after pulling out. That's the coupling closing.

[Charlie Jones]

Originally Posted by Steve Barcak

I would like to know more about these trans too. I have plenty of them in my yard and most or all years too.
What are the gear ratios? As far as Pontiacs, 1961-4, I know they came in Star Chiefs and Bonnevilles. The GPs, Venturas and Catalinas got the slim jims.

What about 1960 and older Pontiacs? Bonne only? or which models?

The "Super Hydramatic" or "Dual coupling" transmission was introduced as a mid-year change to the 1956 Pontiac. The most obvious difference was the addition of a "Park" position to the shift quadrant. This transmission was used in all models of Pontiac through 1960. As mentioned before, in 1961 The "slim jim" trans was introduced for GP's, Catalina's and Ventura's and the "Super Hydro" was only used in Star chiefs and Bonnevilles.
One of the most unique features of this trans was the use of two fluid couplings (read torque converters).The largest one behind the engine served as the main coupling between the engine and trans. The other smaller one, directly behind it, was used lock up the front planetary gearset in direct drive for 2nd and 4th gears.
These transmissions were used for stock class racing back in the day and will as previously noted handle a lot of horsepower.
However; They are larger, much heavier, and more cumbersome than TH 400's. They were only available in a long shaft version. They are also much more expensive to overhaul and modify. Performance parts for them probably don't exist.They are a good choice behind 60 and previous engines , rather than useing pricey adapters for a TH 400. 61 -64 engines only require a starter adapter to use a TH400, at less cost.

[Bill Eveland]

Thats still pretty close to first gear though between the 2 , thanks for the info. I'll see if my uncle has any laying around for future use. I think he still has about 100 Pontiacs.

[stevep]

There are actually a few different length output shafts for these units, form 56-64 in Pontiacs, Olds and Caddy.

[PITTSBURGH 64]

What I know is from my own experience.
I have about $800 in my hydro. $300 in labor, $50 in a lighter weighted governor and $350 for the overhaul kit from Daves Transmissions
http://www.autotran.us/jhmkits1.html.
I removed and installed the tranny myself, I also lifted into my truck by myself after it was rebuilt without fluid.
Mine runs fantastic behind my hi-po 462. I have over 35,000 miles on this set up.
There is no way I could run the same kind of street performance with a 041 cam and a 2.56 posi with a turbo 400. The Turbo 400 (while being an excellent transmission) would need a looser converter (slip=heat=efficiency loss) along with at least a 3.55 rear and that would kill my 18-20 mile per gallon cruising.

If my car was a bracket car I wouldn't think of anything but a 400 Turbo.

For some reason these transmissions were put into the "old junk" catagory along with the 389, the points distributor,the 041 cam and the Quadrajet.

[stevep]

Jeff,

Dave Edwards was at my shop yesterday and we swapped some parts. I have know him for 25 years. He is still driving the 85 Parisienne that I sold him 6 years ago. It is very convenient to have him 5 miles away from me.

[PITTSBURGH 64]

Ya he warned I mean told me about you Steve...........

My trans guy said the kit was going to cost "big bucks" as he put it. He was surprised when I mentioned how much I payed for it. Of course I waited until after he gave me his labor bill.............

[Jack Gifford]

All this talk about 4-speed Hydramatics- I've been enthused about them since I first used a '58 Dual-Coupling back in 1964. I rave about the features, but it usually seems to "fall on deaf ears". Following that trans, I started using a HydroStick, with valve body and most major pieces from HydrMotive. I built it as the "unblown competition" version, so I've never run a blower engine through it. But every time I shift it, I have a mental picture of Montgomery's AA/GS banging through the hydro gears- I swear he spent little more than one second in first! Mine is a '55 Pontiac core, with 4.08 first gear. I ran it mostly with a 3.08 posi, which makes a nice all-around street/touring machine. I didn't run more than 389 c.i., but I can believe that you guys with 455+ could easily handle 2.55 rear gears.
I had to laugh when Detroit starting fitting lockup clutches to torque converters, since the Hydro is "locked up" in 3rd & 4th, ever since it was designed ('39?).
Regarding efficiency, not many automatics have a variable-displacement front pump, as in the Hydro. This feature cuts internal power loss way down, by pumping the minimum amount of oil to maintain required pressures.
A word to the wise- if working on a Dual-Coupling Hydramatic, pay attention to the location of the one shorter front pump bolt. The guy who rebuilt mine back in '64 didn't- which only allowed a trickle of oil flow when the second coupling tried to fill, so 2nd & 4th gear were useless. I had to drive it all the way from the port at Bremerhaven (sp?) to my base near Luxembourg in 3rd gear with 4.11s in the rear! I really didn't like breaking in a new engine for about six hours that way, so I did a bunch of "burst mode" driving on the autobahn- blast the Tri-Power open up to 80/90 MPH or so, coast in neutral down to 40/50 MPH (carefully watching the rear-view), then do it all over again, and again, and ....

[stevep]

Jack,
I had actually done 2 Dual Couplings before I figured out about the short pump bolt. I must have been lucky....they worked fine.

[PITTSBURGH 64]

Well my new lighter 1960 Tri-Power governor has really made a difference. The engine revs up quicker and a little higher. It always seems to be in the right gear now.
Once the holiday police go away I'll be able to really wring it out.
Its a little trick holding a camera while the car is getting a little squirrelly.
http://www.youtube.com/watch?v=EoM8MafcA-A

Shifts nice and positive!
http://www.youtube.com/watch?v=rARX3pYolAQ

[stevep]

Jeff,
I couldn't really tell, but is it upshifting @ 5000 RPM?

[PITTSBURGH 64]

Yes. The shift points are a little longer by a few hundred rpm but the speed at which it gets there is faster. I've been reading the manual to see what G-2 pressure controls.
I started to make TV adjustments but didn't get too far.

[stevep]

I'm glad that it worked the way that you wanted it to work!

[Steve Barcak]

Pittsburgh- I really regret that this thread, and knowledge, didn't come out a month or two earlier. I drove through Pittsburgh when I delivered a Bonneville floor section there. I would love to get a ride in your car to demo this trans.
I think I have close to 2 dozen of them here in cars at Pontiac Heaven. I am not sure I have ever driven one.
Though text is good, it is still hard to understand these trans without the benefit of experiencing it in person. Oh well.

If you like this trans so much, why do you say you would use a TH400 for a bracket car?

I wonder if there is anyone in the Az area who knows how to build one. I wish I could learn to work with them myself but, again, without the experience driving or riding in one, it is hard to understand.
I have driven many of the slim jims and do not like them.

Pontac Jack- What is the difference between a hydro stick and a hydro? I only know these terms from looking at old car magazines. I know they had a following in the gas classes prior to the musclecar era.

Steve Barcak www.pontiacheaven.org

"Real Pontiacs only....no corporate nonsense!"

[PITTSBURGH 64]

Steve, I'm sorry I missed you. I caught the posts of your trip when you were back in Indiana and figured it was too late to invite you to my home.
Looks like I'm going to have to drive to a Pontiac heave event and meet you and Les.

The reason I say that about a Turbo in a bracket car is because I don't know how to rebuild a Super Hydro, yet.
I have the manual and I'm studying the different circuits. My tranny guy said "they are a little complicated but very stout. Get a kit and give it a try on one of your spare trannys".

Its pretty cool when something like this shows up and its been under your nose all along.
One thing I've learned from my Bonneville is these old B bodies were why ahead of there time in engineering.
I once had my car up on the rack at a local Chevy dealer and the mechanics couldn't get over how much the steering and suspension looked like a 90s caprice.

[tom s]

I raced my 63 Lemans in the mid 60s with a Ray Alley(spelling)Engine Master Automotive Hydro.Car ran good,tore your head off when it shifted.Went back to the Muncie.STILL hate auto,JMHO.Tom

[stevep]

Jeff, spend a weekend in Boston. I'll take you to the North End for Italian food (is there any other kind) and I'll give you a crash course in Dual Coupling rebuilds.

[stevep]

Steve B
A Dual Coupling shifts much better than a Slim-Jim. The Dual Coupling does not have that almost 50% ratio change on the 1st shift that makes it fall flat on it's face. The Slim-Jim was one of those things that looked great on paper but just didn't work the way they thought that it would have. The old saying was that the Slim-Jim put AAMCO in business.

[PITTSBURGH 64]

Steve, you got a deal!
I'll need good food and lots of coffee.
Or may be we could get together at Norwalk. I could disassemble my spare hydro and bring the pieces all cleaned up with one of Daves kits.

I can't figure out is why is my car running so much better at take off? Looking at the manual, the governor's G-2 circuit has nothing to do with first gear.
Its some kind of coincidence.
The tranny is more controllable now that I can hold gears longer with more TV (gas peddle opening) pressure. It runs much better now!