Buick Dynaflow was a good transmission

 

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.

 

Inside the Buick Dynaflow

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.

 

 

Automotive History: The Legendary Buick Nailhead V8

By

Paul Niedermeyer

– Posted on January 6, 2021

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(first posted 3/20/2011. Updated 1/5/2021)    Nailhead: what did Buick do to deserve that less than flattering name for its legendary V8 engine from the mid-fifties to the mid sixties? Hemi-head; even flathead are much more lyrical. For those not familiar with Buick’s unusual valve arrangement, we’ll do a primer on that, as well as touch on its brief glory days on the drag strip. But for those already enlightened on the subject, I offer something more: the source and likely explanation of its unusual valve arrangement.

Buick came late to the OHV V8 game, Cadillac and Olds both having introduced their superb engines in 1949. Buick’s venerable straight eight from the thirties at least had overhead valves, unlike the previous Cadillac and Olds flathead engines. That allowed it to stay in the post war game a bit longer with higher compression and multiple carburation. But it was heavy, and not at all suitable for the horsepower war of the fifties that was quickly developing.

In 1953, Buick brought out their new V8, with a very large 4″ bore and quite short 3.2″ stroke, the most oversquare engine on the market at that time. It displaced 322 cubic inches (5.3 L), and  came in 164 to 188 hp variants. In 1954, a small-bore version with 264 CID (4.3 L) reserved for the low end Special arrived.

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The new Buick V8 was relatively light and compact for its time, weighing some 625 lbs. It was built with high quality components, and quickly caught the eye of hot rodders, this being a few years before the Chevy small block came on the market. Its unusual head and valve arrangement made it a narrow engine, increasing its appeal to engine swappers, like this one replacing the six in an old Chevy. But it was precisely that narrow head that also presented serious challenges.

Here’s a nice cutaway of the Buick nailhead engine. What instantly stands out is the unusual arrangement of the valves and valve train, in that they hang vertically in a pent-head or almost hemi-head combustion chamber. We’ll discuss the origins of this later, but note how tortured the exhaust port is, having to make an almost 180 degree bend right behind its valve.

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Just for comparison sake, here’s a cross section of the Cadillac V8 that preceded the Buick by two years. The bigger valves have a mild angle in relation to the head, creating a more typical wedge head combustion chamber. The ports are bigger and smoother, especially the exhaust. Perhaps the most obvious thing about the Buick nailhead is that its arrangement demands very small valves, which seems antithetical to the whole concept of the modern V8 in the first place.

Small they were, hence the “nail head” moniker. The early engines had a 1.75″ intake and a 1.25″ exhaust valve, puny even for the mid fifties. Even the legendary Wildcat 401 from the mid sixties had only a 1.875″ intake and a 1.5″ exhaust; both substantially smaller than the much smaller Chevy V8 engine.

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The explanation generally given is that Buick was focusing on torque rather than maximum breathing at high rpm. And the Buick engines delivered that in spades, typically with more than one ft. lb. per cubic inch, a very respectable output indeed. In the sixties, Buick labeled and advertised their engines on their torque output, not the horsepower, which can be confusing. This Wildcat 445 is a 401 from a 1966 Skylark GS with 325 hp.

But Buick had to use very aggressive camshafts in order to make the nailhead work. By opening the little valves early, and very quickly, much of their limitations were overcome, up to a point. Already the first 322 nailhead had a camshaft that was the equivalent of a “super race cam” at the time; one that would be typically installed from an aftermarket supplier. The intake duration was 282 degrees, and the exhaust 292 degrees, with a 67 degree overlap, along with very steep ramps for extra rapid valve opening.

The camshaft in the 401s were even more aggressive, and those engines were known for their lumpy idle. Not exactly the image Buick typically was trying to convey at the times, with a banker’s Electra 225.

 

Hot rodders found out early that the Buick’s breathing limitations could be overcome by creative solutions. Intake manifolds with every possible combination of carburetors known to man were fabricated.

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Supercharging was an obvious route, by forcing more air through the small ports. Here’s an excellent reprint of a 1954 Hot Rod Magazine article detailing perhaps the first blown nailhead (above), with gobs of technical info on the then new Buick engine.

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Hot rodders were drawn to the Buick nonetheless, at least for a few years before the Chevy V8 and Chrysler hemi established their supremacy. Undoubtedly the most creative and bizarre of all (above) reversed the valve arrangement totally, using a front crank-driven blower to force air through the tiny tortured exhausts, allowing the larger and smooth intakes to now function as exhausts. Take a close look: unbelievable!

The biggest racing fan of the nailhead was TV Tommy Ivo, who started with one in his very successful rail, added a second, and eventually built this legendary quad-nailhead four wheel drive monster. Here’s more nailhead racing history. It’s important to point out that Ivo did not race competitively; he toured the country with his superbly finished machines and ran them in demonstration/show “races” against a local or other circuit racer, which he typically “won”, given the vast superiority of his machines. Ivo retired from drag racing when it became seriously competitive.

The nailhead eventually grew to 425 cubic inches in 1963 for its final three years. In 1967, a whole new Buick generation of V8s appeared, with a very conventional head indeed. I suspect that that the Buick’s pent head was notoriously dirty, and Buick saw the writing on the wall in terms of the coming emission regulations. It’s a curious contrast to the Oldsmobile V8, whose combustion chamber was the exact opposite: it had a very shallow valve angle, and the basic Olds combustion head design survived as one of the last of its breed; in fact the Olds 307 was the last V8 to meet emission regs with a carburetor in 1990.

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So now to my theory about the origins of the nailhead’s unusual design. In 1951, Harley Earl’s famous LeSabre concept appeared, with a radically advanced 3.5 liter (216 CID) aluminum V8 that ran on both gas and methanol. It was supercharged and was rated at 339 hp. Years ago, as a kid, I stumbled on a cross section of the LeSabre engine, and was struck by a certain specific similarity to the nailhead.

The little Buick engine had hemispherical/pent roofed heads, with its valves in the classic formation allowing for large valve diameters. If you look at the intakes on this, one can see that the nailhead used the same unusual arrangement, but for both its valves. The LeSabre/XP 300 engine’s exhaust push rods had a wild arrangement, and were designed to fit into the block between each cylinder.

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It’s quite obvious from this first OHV engine by Buick showed strong interest in the hemi/pent roof head, and that almost certainly Buick had it in mind that their new production engine would also be a genuine hemi, using the same basic configuration as the experimental 215. Given the impact Chrysler’s hemi (above) made in 1951, it’s highly logical and likely.

But almost certainly the expense of building it turned out to be prohibitive. Hence the “half-hemi” nailhead. Buick may also have been planning to offer a high-performance full hemi version of the new engine along with the nailhead, but decided against that.

High cost is precisely the reason Chrysler started offering a simpler and cheaper “poly” head, and dropped its hemis altogether after only seven years, and switched to a wedge shape combustion chamber in their new B-Series engines in 1958.

We’ll likely never know for sure, but the evidence certainly points to this scenario. In any case, it rather backed Buick into a corner, with little valves and a combustion chamber that in the longer run was not so ideal. Half a hemi.

The way to really look at the nailhead is this: it’s similar to a typical four-valve per cylinder pent-roof head of today, but with two of the four valves missing. That’s negating the whole advantage of the hemi/pent head: room for more and/or bigger valves. Buick took a curious half step, one that has left us scratching our heads, but also one that left an enduring legacy nevertheless.