[U47]

Just some information for you A/T guys. Dual coupling also has a split torque feature, but the trans that is more intriguing is Roto. Everyone knows Roto is a three speed. The service manual's description is a four range three speed automatic. The service manual counts torque multiplication in 1st gear at 3.50 to 1 and as the multiplier spools up and driving and driven units equal in speed oil begins to pass directly through it causing it to be a simple coupling and a ratio of 2.93 to 1 and as the factory calls it 2nd range. In third range or second gear the fluid coupling dumps which means the transmission is in full mechanical drive and 1.56 to one. In fourth range or third gear the coupling is now full and the ratio is 1 to 1. The HydraMatic book alternately talks in terms of range and gear ratio, so you have to pay attention to which language they are using as one paragraph it's range and the next it's gear ratio. Roto HydraMatic is considered a dual range Hydramatic with drive rt. (DR' ) and drive left ( 'DR ) Just like Super HydraMatic. and uses the same shift quadrant.
Also stated in the HydraMatic manual is this transmission has split torque and that in fourth range or third gear 40% of the engine torque is going through the fluid coupling and the rest is mechanical connection.
Roto HydraMatic is the only automatic that has a real flywheel instead of a flex plate. Roto is the only automatic that has a fluid coupling and a stator.

[wheneaglesfly]

Originally Posted by U47

Just some information for you A/T guys. Dual coupling also has a split torque feature, but the trans that is more intriguing is Roto. Everyone knows Roto is a three speed. The service manual's description is a four range three speed automatic. The service manual counts torque multiplication in 1st gear at 3.50 to 1 and as the multiplier spools up and driving and driven units equal in speed oil begins to pass directly through it causing it to be a simple coupling and a ratio of 2.93 to 1 and as the factory calls it 2nd range. In third range or second gear the fluid coupling dumps which means the transmission is in full mechanical drive and 1.56 to one. In fourth range or third gear the coupling is now full and the ratio is 1 to 1. The HydraMatic book alternately talks in terms of range and gear ratio, so you have to pay attention to which language they are using as one paragraph it's range and the next it's gear ratio. Roto HydraMatic is considered a dual range Hydramatic with drive rt. (DR' ) and drive left ( 'DR ) Just like Super HydraMatic. and uses the same shift quadrant.
Also stated in the HydraMatic manual is this transmission has split torque and that in fourth range or third gear 40% of the engine torque is going through the fluid coupling and the rest is mechanical connection.
Roto HydraMatic is the only automatic that has a real flywheel instead of a flex plate. Roto is the only automatic that has a fluid coupling and a stator.

I wish I still had the original Rotohydramatic 10 in.my 1963 Grand Prix.
It did indeed use a True Flywheel.
I blew the Slim Jim 10 behind a hot 455 Pontiac in 1998.
I installed a Turbo 400 from.a 1976 Grand Prix 400 ci V8.
It did not slip.right in.
I fabbed and made it work when I was 28 years old.
Never cut the floor pan but I put a few dents with a Ball peen hammer in the floor pan to clear nice.

[U47]

Another interesting thing about all the old HydraMatic's is in the original and original Dual Range transmissions there was a harsh 1-2 shift. Evidently Buick rejected this harsh shift and decided to produce their own automatic ( 1948) deciding it would be a seamless variable ratio transmission. In response for 1956 Cadillac, 1956 Olds s.88 and 98, and 1956 Pontiac StarChief received a new transmission called Controlled Coupling 4 speed HydraMatic. With the old front HydraMatic conventional clutch removed a small fluid coupling was use by alternatively draining and filling was used to control the front planetary gear, because this was done by using fluid in a coupling it softened the I-2 shift.
In 1957 the Controlled Coupling HydraMatic was used in all Cadillac again and in all Olds and Pontiac automatic applications.
1961 Roto appears, there is a real flywheel and the main fluid coupling from Super hydramatic is eliminated and the secondary coupling 8" dia is made to do both duties, but the Roto is a three speed. Roto's problem has always been it's 1-2 harsh shift ( back to the same old problem again ) The reason it's harsh is the trans is going from second range of 2.93 to third range (2nd gear) at 1.56 which is a huge ratio jump, plus 2nd gear or 3r range is pure mechanical connection with no fluid cushion. Controlled coupling goes from 2nd gear at 2.55 to 3rd gear of 1.55 with fluid cushion.
There has been a lot of past scuttlebutt as to why Pontiac was using controlled coupling in StarChief and Bonneville from 1961 -1964 and Catalina, Ventura and Grand Prix useing Roto from 1961-1964.
Remember all Oldsmobiles used Roto from 1961 to 1964. Olds was the only U.S. GM car to use the model 5 and model 10 Roto. The F-85 and cutlass "Y" bodies got the smaller #5 Roto. Most of the scuttlebutt revolves around Oldsmobile. Oldsmobile didn't make enough cars to justify Roto's existence and so Pontiac was forced by the corporation to take Roto for it's short wheel base cars so that Roto could show profitability.

[wheneaglesfly]

Originally Posted by U47

Another interesting thing about all the old HydraMatic's is in the original and original Dual Range transmissions there was a harsh 1-2 shift. Evidently Buick rejected this harsh shift and decided to produce their own automatic ( 1948) deciding it would be a seamless variable ratio transmission. In response for 1956 Cadillac, 1956 Olds s.88 and 98, and 1956 Pontiac StarChief received a new transmission called Controlled Coupling 4 speed HydraMatic. With the old front HydraMatic conventional clutch removed a small fluid coupling was use by alternatively draining and filling was used to control the front planetary gear, because this was done by using fluid in a coupling it softened the I-2 shift.
In 1957 the Controlled Coupling HydraMatic was used in all Cadillac again and in all Olds and Pontiac automatic applications.
1961 Roto appears, there is a real flywheel and the main fluid coupling from Super hydramatic is eliminated and the secondary coupling 8" dia is made to do both duties, but the Roto is a three speed. Roto's problem has always been it's 1-2 harsh shift ( back to the same old problem again ) The reason it's harsh is the trans is going from second range of 2.93 to third range (2nd gear) at 1.56 which is a huge ratio jump, plus 2nd gear or 3r range is pure mechanical connection with no fluid cushion. Controlled coupling goes from 2nd gear at 2.55 to 3rd gear of 1.55 with fluid cushion.
There has been a lot of past scuttlebutt as to why Pontiac was using controlled coupling in StarChief and Bonneville from 1961 -1964 and Catalina, Ventura and Grand Prix useing Roto from 1961-1964.
Remember all Oldsmobiles used Roto from 1961 to 1964. Olds was the only U.S. GM car to use the model 5 and model 10 Roto. The F-85 and cutlass "Y" bodies got the smaller #5 Roto. Most of the scuttlebutt revolves around Oldsmobile. Oldsmobile didn't make enough cars to justify Roto's existence and so Pontiac was forced by the corporation to take Roto for it's short wheel base cars so that Roto could show profitability.

Thank You.
My 1963 Grand Prix Launched like an Animal with the Rotohydramatic Slim Jim 10.
The Low 2.97 1st. 455 Pontiac. & 3.23 Posi 9.3 Rear.
I was really sad when I blew up the original trans.
1-2 upshift was harsh. I didn't care.
My Big Tin Indian Hooked hard and Took off fast on the street.
Turbo 400 has not failed but it does not have the same low 1st gear.

Not sure what I am going to do with my 1964 Super Hydramatic Dual Coupling trans.
I researched online and no market really to sell it.
I did read its strong enough to take 455 Torque on the street.
A later cousin that the B& M Hydro was based off of.
Gasser Guys LOVED THEM.

[U47]

Originally Posted by wheneaglesfly

Thank You.
My 1963 Grand Prix Launched like an Animal with the Rotohydramatic Slim Jim 10.
The Low 2.97 1st. 455 Pontiac. & 3.23 Posi 9.3 Rear.
I was really sad when I blew up the original trans.
1-2 upshift was harsh. I didn't care.
My Big Tin Indian Hooked hard and Took off fast on the street.
Turbo 400 has not failed but it does not have the same low 1st gear.

Not sure what I am going to do with my 1964 Super Hydramatic Dual Coupling trans.
I researched online and no market really to sell it.
I did read its strong enough to take 455 Torque on the street.
A later cousin that the B& M Hydro was based off of.
Gasser Guys LOVED THEM.

Remember Roto is a 4 range three speed and that means;
1st range 1st gear 3.50 with stator multiplication coming out of the hole
2nd range 1st gear 2.93 without stator multiplication as the unit winds up at high speed in that gear
3rd range 2nd gear 1.56
4th range 3rd gear 1:0 to 1:0

What is the condition of your Super Hydramatic?

FYI The B&M HydraMatic was a reworked Dual Range single coupling HydraMatic the best ones were the 1955-56 slant pan versions. B&M also made up a beefed T400 trans. I don't believe they ever did the Super HydraMatic / Dual Coupling HydraMatic. If I used one behind a 455 I would drive it very sanely.

[wheneaglesfly]

Originally Posted by U47

Remember Roto is a 4 range three speed and that means;
1st range 1st gear 3.50
2nd range 1st gear 2.93
3rd range 2nd gear 1.56
4th range 3rd gear 1:0 to 1:0

What is the condition of your Super Hydramatic?

Excuse me. Your right about the Rotohydramatic gear ratios.

The Super Hrdamatic trans I have appears to be in decent shape.
The 389 & Superhydramatic trans were actually installed in a 1963 Grand Prix that came from Chicago.
No trans crossmember attached. An abandoned project.
I should have bought the entire car but didn't.
Just bought the engine and trans Superhydramatic.
I had no.idea for 8 years what trans I had.
I grew up around Muslecars.
Very few. Old Time Pontiac guys left....1963-64 & earlier .

[U47]

Well the Super HydraMatic would have to be a known good working unit with ALL the linkage to the trans and to the carburetor including the crosspiece to the frame. It would probably have to come apart for seals because it's been inactive for so long. I added some B&M information on my last thread after you posted your last one.
FYI The ratio's for Super HydraMatic are
1st 3.97
2nd 2.55
3rd 1.55
4th 1 to 1

[wheneaglesfly]

Originally Posted by U47

Well the Super HydraMatic would have to be a known good working unit with ALL the linkage to the trans and to the carburetor including the crosspiece to the frame. It would probably have to come apart for seals because it's been inactive for so long. I added some B&M information on my last thread after you posted your last one.
FYI The ratio's for Super HydraMatic are
1st 3.97
2nd 2.55
3rd 1.55
4th 1 to 1

Yes I agree.
It should be rebuilt before reuse.
I am the Drag racing type on the street.....The Super Hydramatic has a Gear ratio 1st like the Modern Dodge Hellcats with 707 Hp that is actually 780 Hp Flywheel.
And like the $100,000 ZO6 Corvette.

Gearing is everything Drag Racing.

[Jack Gifford]

Originally Posted by U47

... Roto HydraMatic is the only automatic that has a real flywheel instead of a flex plate...

I'm guessing you meant to say "the only automatic with a torque converter that has a flywheel; since all the Dual-Range HydraMatics used true flywheels. [It's also noteworthy that the Dual-Range flywheels and torus covers were high-tensile steel, which earned them an exception from NHRA-mandated shielding]

[Jack Gifford]

Originally Posted by Jack Gifford

... My misunderstanding may come back to bite me, in a very real way. The HydroStick I'm putting in my GMC will mark the first time I've used torus members cut for higher stall speed in a road-going vehicle- I was thinking the coupling would have no influence in 3rd and 4th gear. But it might turn out to be "looser" than desired when at-speed on the highway...

Here's the follow-up on that concern I had four years ago- since I finally got the GMC on the road in August of 2014:

The stall-speed of the modified coupling (brakes locked, half-throttle on the center carb) is right where I hoped, at 3,200 RPM. But in normal driving it acts pretty much like a stock coupling. In 3rd & 4th gear it feels like driving a standard transmission, just as a stock Dual-Range does- almost no tach movement when changing between acceleration and engine-braking.

[U47]

Originally Posted by Jack Gifford

I'm guessing you meant to say "the only automatic with a torque converter that has a flywheel; since all the Dual-Range HydraMatics used true flywheels. [It's also noteworthy that the Dual-Range flywheels and torus covers were high-tensile steel, which earned them an exception from NHRA-mandated shielding]

Well no Roto has a fluid coupling which happens to have a stator in it.
Are you saying the torus assembly on a Dual range or single range is a flywheel?

[Bill Hanlon]

The flywheel is the "front" of the torus cover. A bowl-shaped cover bolts to the flywheel to finish the cover. 30 bolts.

[U47]

Originally Posted by Bill Hanlon

The flywheel is the "front" of the torus cover. A bowl-shaped cover bolts to the flywheel to finish the cover. 30 bolts.

Yes, I know that and Dual coupling also has that, but no HydraMatic or any other automatic has a flywheel in the description of a real flywheel of a stick shift car except Roto. It's a stand alone heavy chunk of change.
There has always been a incorrect statement that Roto has a torque converter. It does not. Roto has a fluid coupling that happens to have a stator in it. Hydramatic service manuals confirm this to be true. Inspection reveals the straight vanes all couplings have in common. Take the stator out and you have a simple coupling. Take the stator out of a torque converter automatic and you still have a torque converter because the vanes are curved.

[wheneaglesfly]

Originally Posted by U47

Yes, I know that and Dual coupling also has that, but no HydraMatic or any other automatic has a flywheel in the description of a real flywheel of a stick shift car except Roto. It's a stand alone heavy chunk of change.
There has always been a incorrect statement that Roto has a torque converter. It does not. Roto has a fluid coupling that happens to have a stator in it. Hydramatic service manuals confirm this to be true. Inspection reveals the straight vanes all couplings have in common. Take the stator out and you have a simple coupling. Take the stator out of a torque converter automatic and you still have a torque converter because the vanes are curved.

I like Old Tech by the way.
Nothing wrong with modern high tech but I am around it daily .
Gets Boring.

What kind of Friction plate material is used in.these old Rotohydramatics & Super Hydro Dual Coupling transmissions ?
Do they offer Eagle Red Alto frictions, Kolene Salt Bath treated Steels & a Carbon Fiber Band(s) ?
I have rebuilt and blueprinted Turbo 400, TH 350, 700R4, 4L60E & others non GM.

[Jack Gifford]

Originally Posted by U47

... no HydraMatic... has a flywheel,,, except Roto. It's a stand alone heavy chunk of change...

You've never handled a Dual-Range flywheel apparently.

Originally Posted by U47

... There has always been a incorrect statement that Roto has a torque converter. It does not...

??? You're saying the Roto device doesn't perform torque multiplication?

Originally Posted by U47

... Take the stator out of a torque converter automatic and you still have a torque converter because the vanes are curved...

No.

[U47]

Originally Posted by Jack Gifford

You've never handled a Dual-Range flywheel apparently.

??? You're saying the Roto device doesn't perform torque multiplication?

No.

Jack , just read what I said.

Yes, I have handled a dual range transmission, but a torus cover is not a flywheel in the traditional sense. Even though a Turbo 400 has a flex plate and a torque converter both together perform a flywheels function as well as connecting the engine to the transmission nether part or the sum is referred to as a flywheel and that goes for the Single, Dual Range, and dual Coupling. Roto is different. If you were to take a torus cover assy to someone who's never worked on one you wouldn't get a flywheel answer, but if you took a Roto's flywheel to him he would have no problem calling it a flywheel.
Straight angle vanes are what differentiate a coupling from a torque converter which has curved vanes. Take the "Acceler-Rotor" out of the coupling and you have a fluid coupling. Roto has a coupling with a fix angle stator and multiplies torque in the first stage only, after that oil passes straight through in 2nd and 4 range and is empty in 3rd range ( mechanical connection ). The Pontiac HydraMatic Book, the Oldsmobile HydraMatic Book and HydraMatic division ALL call Roto's little 8" coupling a fluid coupling. They should know They made it.

[stevep]

John Sawruk told me that the Roto was an Oldsmobile design, which, to me, explained why Olds only had them.
Is that correct?

[wheneaglesfly]

So what happened to all the Rotohydratic 10 & Super Hydramatic transmissions ?
All the originals get tossed and a Turbo 400 or Turbo 350 get installed ?
Or converted to a Super T-10. & Muncie 4-speed
Or a Tremec TKO 5-speed or 6-speed manual ?

I don't ever see any Super Hydramatics or Roto 10 Slim Jims for sale.
One guy on Ebay rebuilds Super Hydramatic -Olds Jetaway Transmissions.
$2,500 some dollars exchanged.

[U47]

Originally Posted by stevep

John Sawruk told me that the Roto was an Oldsmobile design, which, to me, explained why Olds only had them.
Is that correct?

Roto is a design by HydraMatic Division.

At first Oldsmobile Division was to use the transmission, however Oldsmobile didn't sell enough cars to make Roto pay for itself, therefore the Corporation directed Pontiac Division to use them in their short wheelbase cars.
All Oldsmobile's with automatic's got them including the model 5 ( small version of the 10 ) for F-85 and Cutlass ( 1961 -1963) and model 10 All large full size from 1961-1964.

All short wheelbase Pontiac B bodies ( Catalina, Ventura, Grand Prix ) got Roto model 10 from 1961-1964.
All long wheelbase Pontiac's continued to ues Super HydraMatic known by it's creator ( HydraMatic Division ) as Controlled Coupling HydraMatic.

Cadillac also continued to use Controlled coupling to 1963. In 1964 some Cadillac's used Controlled coupling while other models along with some Buick's got the new ST400 Torque converter automatic. That automatic was a switch pitch T400.

[U47]

Originally Posted by wheneaglesfly

So what happened to all the Rotohydratic 10 & Super Hydramatic transmissions ?
All the originals get tossed and a Turbo 400 or Turbo 350 get installed ?
Or converted to a Super T-10. & Muncie 4-speed
Or a Tremec TKO 5-speed or 6-speed manual ?

I don't ever see any Super Hydramatics or Roto 10 Slim Jims for sale.
One guy on Ebay rebuilds Super Hydramatic -Olds Jetaway Transmissions.
$2,500 some dollars exchanged.

GM stopped making them that's what happens. Not everyone tossed either type of trans. I have a perfectly healthy 63 Catalina that has it's original Roto and it works very well. Most were not converted to stick shift. In the late 60's and early 70's most of the converted ones were converted to T-400. Now there has been quite a few going to 200R4 or 7004r.