The twin turbine Dynaflow was a good transmission if you manually used
low gear. That transmission did not automatically start off in low;
thus, by manually using low gear you could increase the power to the
rear wheels by 43 percent. This was a huge power increase by just using
low gear.
My dad had a 63 225 sport sedan with the 401 dynaflow. He use
to say low gear all the way. He would manually use low gear up to 65-70
MPH with a 3:23 rear end and then shift into drive. With cheater slicks
he would turn a 15.2 1/4 @ 88 to 89 MPH. However, a lot of races were
lost because people do not know you have to manually use low gear with
the dynaflow. I saw a guy in a 425 63 Riv. flooring his Buick off the
line in drive with just a tire chip; he did not know that you need to
use low gear manually.
You can increase your power by 43 percent in low
gear. Moreover, most test times listed are using the dynaflow are done
in drive-that is why the 1/4 performance is so lousy. If they used low
gear it would be a lot better at least 43 percent better. Auto-catalog
list the 1963 225 at 16.9 in the 1/4 mile and if you look at the small
print it tells you that they use drive gear only. This is not a true
test of what the Dynaflow Buicks will really do performance wise.
From 1948 through 1963, Buicks were like no other cars on the road, because they were equipped with Dynaflow Drive.
Like many of the early innovations in automatic transmissions at
General Motors, the Dynaflow was the work of GM engineer Oliver K.
“O.K.” Kelley, the kind of rare talent who could fairly be called a
mechanical genius. Born in Salo, FInland in 1904 as Olavi Koskenhovi, he
came to the United States as a teenager, Americanized his name, and
earned bachelor’s and master’s degrees in engineering from Chicago
Technical College. He entered the auto industry as a draftsman at Nash
in 1925, and in 1929 he went to work for GM’s Truck and Coach division,
where he found his calling in specialized transmissions and couplings.
In 1936, Kelley joined Earl Thompson’s transmission engineering team
at GM, developing the original Hydra-Matic, and when Thompson left GM in
1940, Kelley took over his position. Small world department, Motor City
desk: Among other things, Kelley is the man who, in 1956, invited
Packard engineer John Z. DeLorean to come to work at GM.
Introduced in 1948, the Dynaflow transmission arose from a special
set of needs at the Buick Motor Division. Unlike Oldsmobile, Cadillac,
and Pontiac, Buick pushed back against adopting the corporate
Hydra-Matic automatic transmission. While the Hydra-Matic was a major
breakthough it was not without its shortcomings, including firm gear
changes (downright harsh, some would say) especially on the 2-3 upshift.
This property was a poor fit with the classic Buick driveline of the
period, which used a rigid torque tube assembly suspended by a pair of
plush coil springs at the rear. Here, a stiff upshift could send a shock
wave though the entire drivetrain, the car, and through the passengers
too—unacceptable behavior for a fine car like Buick. In those days, the
straight-eight Buick was prized for its luxurious quiet and smoothness.
With the Dynaflow, Kelley and his staff solved the problem by
eliminating mechanical upshifts altogether. While the Hydra-Matic used a
simple 1:1 fluid coupling and planetary gearsets to provide the torque
multiplication for acceleration, the Dynaflow employed a five-element,
dual-stator torque converter with an effective mechanical advantage of
3:1. (The engineering was based in part on the Torqmatic, a transmission
developed by GM’s Detroit Transmission division for the M-18 Hellcat
tank destroyer in WWII.) As the Dynaflow-equipped vehicle took off from a
dead stop and accelerated to highway speed, the driver never felt any
perceptible upshifts, because there weren’t any. All the work was done
by the torque converter.
The original Dynaflow did include a planetary gearset section to
provide a mechanical 1.8:1 first gear and a reverse, but the
transmission was incapable of engaging them automatically—they had to be
manually selected by the driver via the column-mounted lever. (The
selector pattern was PNDLR.) In this property the Dynaflow was similar
to the Chevrolet Powerglide that appeared a few years later. (Read our
Powerglide feature here.)
And just as the Powerglide won the cruel nickname “Slip-and-slide,” the
Dynaflow became known as the “Dynaslush,” or even worse, “Dynaflush.”
While it’s true that the Dynaflow suffered more slippage than
conventional automatics, what the driver felt was an odd disconnect
between flywheel and road wheels, engine speed and road speed. Gliding
along at highway speed it was hardly perceptible, but when the pilot
mashed down on the throttle for full acceleration, the sensation was
blatantly evident. But fortunately, most Buick drivers didn’t typically
drive that way.
Over its 16-year production life the Dynaflow was continually
updated. Shown above is Mrs. Thelma Hill, a secretary at the Buick
Dynaflow plant in Flint, with a 1946 prototype (left) and the new and
improved 1956 version. In 1953 came the Twin Turbine Dynaflow, which
employed a single stator with a dedicated planetary gearset, and in 1956
an additional stator was added to make the transmission feel more like a
conventional automatic. A more sophisticated variant called the Flight
Pitch Dynaflow (optional at extra cost and later renamed the Triple
Turbine) was introduced in 1958, but it was fraught with bugs and
dropped after ’59.
Throughout its life, the Dynaflow was a Buick exclusive at General
Motors with one brief exception. In August of 1953, the giant new GM
Hydra-Matic plant on Plymouth Road in Livonia, just west of Detroit,
burned to the ground. (At the time, it was the largest industrial fire
in history.) As GM scrambled to keep the production lines running for
all its passenger car brands, several hundred Oldsmobiles and around
28,000 Cadillacs that year were equipped with Buick Dynaflow
transmissions.
While the Dynaflow name was dropped after 1958, the transmission
itself lived on (often called “Turbine Drive”) at Buick through 1963,
when the Turbo-Hydramatic transmissions arrived. If there is one word
that could sum up the Dynaflow today, it’s probably misunderstood. While
the “Dynaslush” won its share of derision in its day, that came mainly
from people who wouldn’t have purchased Buicks anyway. Among traditional
Buick owners, Dynaflow was well regarded. Manual transmissions were
available on many Buick models throughout the Dynaflow era, but buyers
were relatively rare. For Buick cars and Buick drivers, the Dynaflow was
the right transmission for the time.
Original version
The Dynaflow was an automatic transmission used in various forms in Buick cars by the General Motors Corporation from 1947 until 1963. The transmission initially used a five-element torque converter, with two turbines and two stators, as well as a planetary gearset
that provided two forward speeds plus reverse. In normal driving,
Dynaflow started in high gear (direct drive), relying on the converter's
3.1:1 torque multiplication, Ref. 1963 Buick Service Manual to
accelerate the vehicle. Low gear, obtained via the planetary gearset,
could be manually engaged and held up to approximately 60 mph (97 km/h),
improving acceleration.[1]
The transmission was incapable of automatic shifting, requiring
the driver to move the shift lever from low to drive to cause an
upshift. Buicks equipped with the Dynaflow transmissions were unique
among American automobiles of the time in that the driver or their
passengers would not detect the tell-tale interruption in acceleration
that resulted when other automatic transmissions of the time shifted
through their gears. Acceleration through a Dynaflow was one smooth (if
inefficient and slow[1]) experience. It was because of this slow acceleration that the Dynaflow transmission was nicknamed "Dynaslush."[3]
The Dynaflow was an inherently inefficient design due to its sole
reliance on the torque converter in normal driving. Exacerbating the
situation was the dual stator arrangement, which wasted more power than
the simpler three element converters used with other automatic
transmissions, such as Chrysler's TorqueFlite. The multiple stators increased turbulence in the converter, even when operating in the coupling phase.
Design rationale
During
the Dynaflow era, many of Buick's unique engineering features ranked
smoothness above most other design and marketing objectives. Dynaflow's
non-shifting design was demonstrably smoother than the rough shifting
automatics then available. Moreover, Buick's torque tube "live axle" rear suspension design, which incorporated a rigid drive shaft with just one single universal joint
("U-joint") at the front end of the driveshaft, was said to amplify the
harshness of contemporary automatic shifting transmissions. Dynaflow's
non-shifting design addressed this characteristic of Buick's driveline. Torque tube rear suspension was a simple design that enabled Buick to use soft coil springs while its competitors, including its corporate cousins, used harsher, firmer leaf spring, Hotchkiss drive rear suspension.
Dynaflow's smooth but inefficient five element torque converter which fed power through a non-shifting direct drive (plus one manually selectable "Low gear" of 1.8:1) was the conceptual polar opposite from the Hydra-Matic used by its sister GM divisions Oldsmobile, Cadillac and then Pontiac.
The contemporary Hydra-Matic, the world's first large scale successful
automatic transmission, used a simple two element fluid coupling — a
more efficient device than a torque converter but which provided no
torque multiplication — to feed power to its fully automatic four
speed planetary gearbox. Hydra-Matic's high number of gear ratios for
the day compensated lack of a torque converter by including an
exceptionally low first gear of 4:1. Other contemporary automatics
followed the middle ground by using two or three automatic shifting gear
ratios along with a relatively simple three element torque converter.
Three element torque converters continue to be the norm — albeit
"tighter", more efficient and less torque multiplying torque converters —
even as the number of discrete gear ratios in modern 21st Century
automatics continues to increase to as many as ten.
The Dynaflow's gearbox section was derived from Chevrolet’s Powerglide, a two speed fully automatic planetary
transmission incorporating a conventional three element torque
converter. Two speed automatics with three element torque converters
were common for lower priced cars of the day and in the Chrysler PowerFlite as used in the entire Chrysler Corporation lineup through 1956.
Performance
Dynaflow’s
inefficiency earned Buick a reputation as a “gas hog” even when
compared to heavy, powerful luxury cars of the 1950s and early 1960s.
But at the time, gasoline was cheap and Buicks were upscale cars, so the
"gas hog" reputation was not a serious sales deterrent.
Manually "downshifting" from the direct drive “Drive range” to
the 1.8:1 “Low range” enabled Buick's “torque monster” engines to
provide very good acceleration, though frequent “downshifting” took a
serious toll on transmission reliability. Arguably, a Buick “family car”
wouldn't fare well during the teenage son's weekly “date night Friday”
outings.
Engine RPM
seemed to be more a function of accelerator pedal position than of
actual road speed. "Flooring" the accelerator pedal would cause the
engine speed to flare (even though there is no automatic downshift and
no torque converter lockup to disengage). As the car would accelerate,
RPM would further climb, but by a disproportionately smaller amount.
Even more strangely, manually downshifting (see above) with the gas
pedal already "floored" would not increase RPM in proportion to the
1.8:1 drop in gear ratio. The Dynaflow aural experience was similar to that of a Continuously Variable Transmission
(CVT) (though modern electronically controlled CVT's address this
throttle position dependent engine speed (and sound) characteristic by
artificially inserting stepwise ratio changes instead of a truly continuous or constant rate change in order to simulate more driver-satisfying genuine shifts).
1953 redesign
In 1953, Buick redesigned the Dynaflow, calling it the "Twin Turbine Dynaflow".
The converter now incorporated two turbines and a planetary gear set,
with a single stator. The first turbine was linked to the ring gear and
the second to the planets, which gave a 2.5:1 torque multiplication
which was now partly mechanical. This resulted in better efficiency,
especially at highway speeds, and a higher level of performance and no
penalty regarding the trademark smoothness. Buick also incorporated a
variable-pitch stator in 1955 for greater flexibility. While these
changes improved the transmission's overall performance and efficiency,
the Dynaflow still was no match for other designs that utilized three
element converters with automatic shifting.
1956 Redesign
In
1956 a second stator was designed into the torque converter at the
outer diameter of the turbines. This provided a Stall Ratio of 3.5:1
making the performance comparable to other automatic transmissions of
the time. This design continued until the end of production of the Twin
Turbine Drive in 1963. However, the Triple Turbine ended production in
the end of the 1959 model year, leaving the original Dynaflow Twin
Turbine the only automatic available in full-size Buicks.
1958 redesign
A
final version appeared in 1958 incorporating three turbines that Buick
named the Flight Pitch Dynaflow. Buick made this transmission standard
on its top-of-the-line Roadmaster 75 and Limited models and optional on
all others. This version was further refined for 1959 and renamed the
Triple Turbine but was offered only as an option on all models (Buick
dropped the "Dynaflow" name after 1958). This unit was similar to the
Twin Turbine, but had a variable pitch stator that increased converter's
torque multiplication to 3:1.
The stator element of the torque converter has two blade
positions, controlled by the driver via the accelerator pedal to offer a
'passing gear' and extra response at any speed from heavy throttle
application. In normal driving the stator blades are arranged at
'cruise' angle, with improved efficiency and response at light throttle.
Opening the throttle changes the angle of the stator vanes
hydraulically to 'performance angle', which permits the converter to
achieve stall about 1000 rpm higher than in 'cruise'. In this situation
oil is redirected to strike the next-lowest drive turbine, which
effectively lowers the drive ratio, and allows engine speed to flare to a
speed where output is greatest.
A few identifying features: the older Twin Turbine model was
fitted with a rear pump, which meant the vehicle could be push-started
(considered desirable at the time). Also, the Twin Turbine would allow
engagement of low gear up to 40 mph (64 km/h), and had a shift quadrant
that read P-N-D-L-R. In contrast, the Triple Turbine unit did not have a
rear pump, and could not be push started. It would allow engagement of
low gear up to 45 mph (72 km/h), and had a shift quadrant that read
P-R-N-D-G (where "G" stood for "grade retard"). The grade retard
feature was not designed as a low or forward acceleration gear and was
meant to be used only on long declines to generate a degree of engine
braking. The Triple Turbine was cancelled after 1959 due to technical
problems and poor sales with only the Twin Turbine being produced until
1963.
In the late 1950s the Buick division of GM collaborated with Darby Buick of Sarasota, Florida to investigate potential marine uses of the Dynaflow transmission. The test boat was a 21-foot Correct Craft.
The engine was a 364 CID Buick with a four barrel Rochester carburetor
of nominal 300 gross hp. The boat could attain a speed of about 60 mph
(96 km/h), which was considerable for the time, but the transmission
suffered from two problems. First, the torque in reverse was excessive,
although this could have been alleviated with different gear ratios.
Second, the state of "Park" in a car necessitated a stopped drivetrain.
Without the locked-in-place tires of a car, it was difficult to put the
transmission into the equivalent of "Park."
Termination
In 1964, the Dynaflow was discontinued in favor of the more efficient
Super Turbine 300 two-speed and
Super Turbine 400 three-speed transmissions, Super Turbine 400 being Buick's trade name for the
Turbo-Hydramatic.
One feature of the Dynaflow, the variable-pitch torque converter
stator, colloquially the "Switch-Pitch", lived on in versions of the
Turbo-Hydramatic (Super Turbine 400) fitted to full-size Buicks,
full-size
Oldsmobiles and
Cadillacs built from 1965–1967, as well as the Buick Super Turbine 300 and Oldsmobile Jetaway from 1964–1967.