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The Chrysler-Plymouth-Dodge-DeSoto Powerflite automatic transmission

powerflite automatic

Chrysler wrote in 1954: “PowerFlite, which requires no clutch pedal, combines a torque converter and a two-speed planetary gearbox in a smooth-flowing driving operation. It is 100 poounds lighter than the heaviest competitive unit, and contains 110 fewer parts than the most complicated of these. Dodge engineers claim it will deliver more accelerating power more smoothly than any other transmission. Neutral and drive are on one lovel of the selector level. Reverse and low gears, on a higher level, are selected by a slight lifting of the lever and sliding left or right. This makes it possible to select a driving range by feel. Also, because reverse is next to neutral, it eliminates the dangerous practice of switching directly from drive to reverse.”

1960 automatic transmission tuning TorqueFlite (V8) TorqueFlite (I-6) PowerFlite
Light throttle 1-2 shifts starting from... 10 mph 9 mph 11 mph
Light throttle 2-3 shifts starting from... 15 mph 14 mph No 3rd gear
Heavy throttle 1-2 shifts 40 mph 23 mph 55 mph
Heavy throttle 2-3 shifts 75 mph 60 mph No 3rd gear
Kickdown, 2-1, if speed is less than: 25 mph 22 mph 50 mph
Kickdown, 3-2, if speed is less than: 65 mph 60 mph  
Low gear button operates at (maximum): 25 mph 22 mph 50 mph

Though long in coming, the Powerflite, introduced in 1954, is an obvious example of the famed Chrysler engineering. The engineers had done their homework well in creating this two-speed planetary "gearbox" with a torque converter. It started in low, unlike some Fordomatics, shifting into high at eleven miles per hour. It could also be manually held in low, and the car could be push started without any damage to the transmission.

Its one negative drawback was the lack of a Park position or a lock-up in Reverse. This made an effectively operating parking brake a necessity. Consequently, the latter was changed to an internal-expanding unit mounted on the transmission tail shaft as was the external-contracting brake on the manual gear box.

powerflite

The quality of the Powerflite design is well attested to by the fine, long-lived reputation of its three-speed successor, the famous Torqueflite, arguably the best automatic transmission to come out of Detroit, if not the world.

This section contributed by Curtis Redgap. Click here to read more of his articles.

Not much credit is given to the Powerflite transmission. Probably because it was overshadowed by the absolute best automatic transmission ever built, the Chrysler Torqueflite. Yet, the Powerflite soldiered on even after the introduction of Torqueflite into the 1961 model year. A seven year run. It was a simple transmission built around a planetary gear set, not unlike the early Model T Ford; it was also very strong, handling any engine that Chrysler built, and it was simple, with far fewer parts than its competition from Ford, GM, Studebaker, or Packard.

Powerflite automatic transmissionIn one of its strangest applications, the Los Angeles Police equipped its 1960 Plymouth Savoy fleet (330 units) with a 318 cubic inch V-8 and the Powerflite transmission. It was unusual because the vastly superior Torqueflite had been around for three full years, and was king of the fleet buyer's specifications — but the LAPD specified that the transmission had to share the oil with the engine!

It was an odd demand that lasted several years. Only Chrysler was able to meet the specifiication, and virtually without any changes to the transmission itself. Chevrolet's Powerglide could not make it, nor could Ford's 2 speed Fordamatic. Both of those destroyed themselves within a few hundred miles with 20 weight engine grade oil. The Powerflite and later Torqueflite soldiered on like nothing happened.

LA also purchased 303 1961 Dodge Darts equipped the same way as the 1960 Plymouths. No reported extensive transmission problems occured.

The Powerflite was discontinued after 1961 (the Hy-Drive only had about one year).

pushbutton transmission controls

Other notes

In 1955, the Powerflite automatic was given an unusual dash-mounted lever. In 1956, the pushbutton automatic was introduced with the Torqueflite automatic, continuing experimentation with new ways to change gears. At least one owner complained about the gear ratios with the Powerflite, which reduced acceleration considerably compared with the manual gearbox.

powerflite

Mike Peterson wrote in the Walter P. Chrysler Club magazine:

The 6 cylinder and V8 transmissions in 1955 were all the same except the clutches. These transmissions have a tailshaft parking brake which simplifies the rear brakes. 1955 was the only year for the automatic transmission lever mounted on the dash, although Corvair used that location for awhile.

The PowerFlite transmission is air-cooled, as is the torque converter. The absence of a vacuum modulator enhances the simplicity of this unit. On the V8 car a full throttle upshift occurs at about 60 mph. Kick-down will occur all the way up to 50 mph.

pushbuttons

One of the idiosyncracies of the design is a very high (260 lb/sq.in.) fluid pressure when the transmission is in reverse. The life of the PowerFlite can be extended by first shifting to drive (foot on the brake) to cut the engine idle speed and then go into reverse. I have been doing that since my rear band broke and it seems to work great. During a rebuild, transmission life will also be extended by installing the kick-down cushion spring in the trash can, not in the PowerFlite. This spring softens the shift by momentarily holding the transmission in low and drive during kick-down, and really puts a strain on the internal components.

One of the nice things about the PowerFlite is that it comes with the four pinion rear axle. The four pinion unit is the stronger of the two offered in 1955 and, when coupled to the PowerFlite, will last forever and a day. In 1956 the four pinion axles were high performance options. 3.54 is a standard rear gear with the PowerFlite, 3.73 is an optional ratio. Manual transmission sixes got 3.9, 4.3 with overdrive; the V8 counterparts received 3.73, 4.1 with overdrive. These are the two pinion units and do not appear to be as strong as the four pinion units.

Chrysler wrote about the Powerflite in 1957:

PowerFlite no-clutch automatic transmission has a unique record for delivering care-free service. The design has been right, and right from the start. PowerFlite also has the advantage of push-button control...within easy reach of the driver, but away from any other hands (particularly from young fingers) ... To start, press button N (Neutral), turn the ignition key, press button D (Drive), step on the accelerator to go - touch the brake to stop - gears will change silently, automatically, to meet the driving need. ... The L button holds the transmission in lower gear if you want the safety of engine braking for a long, steep grade. The pushbuttons are illuminated for night driving. Automatic lockout is a safeguard in case you accidentally pressed the Reverse button when the car is moving forward above 10 mph. (Thanks, Brendan Lepschi)

In 1960, Chrysler wrote that, for safety, the car had to be started in Neutral; and if the car was moving at 10 mph or more, Reverse would drop the car into Neutral as a safety feature. Likewise, the low gear or 1 button would be ignored if the speed was already too high.

Click here for the main transmissions page

Click here for a page on the Hy-Drive transmission.

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