Fluid Drive was a fluid coupling between the engine and the clutch. The
starter ring gear was attached to the Fluid Drive unit. It was first
introduced on the 1939 Chrysler Cutom Imperial in 1939, the rest of the
Chrysler line in 1940, Dodge and DeSoto in 1941. It was kast used in 1953 .
Fluid Torque Drive was introduced for 1951 on the new hemi Chryslers. It
replaced the fluid coupling with a true torque converter with the oil pump
located just to the rear of the converter. DeSoto adopted it for 1952 and
Dodge in 1953. The 1953 versions used the engine oil as the source for the
oil and pressure for the torque converter.
Plymouth introduced Hy-Drive in mid-1953. It was basically Fluid Torque
Drive with another name.
Note that Fluid Drive, Fluid Torque Drive and Hy-Drive are not
transmissions.
Hydramatic was a true automatic with a fluid coupling instead of a torque
converter introduced in 1940. It was built by General Motors, not Chrysler.
The 1939 Chrysler Custom Imperial mated the Fluid Drive unit to a 3-speed
transmission. This permitted a driver to start off in any gear from a dead
stop and stop the car without using the clutch or changing gears.
In 1941 Chrysler introduced its 4-speed semi-automatic transmission. It had
two forward ranges with low and high gear in each range. You needed the
clutch to shift between low, high and reverse. To shift from the low gear
to high gear in each range, once speed reached about 7 mph in low range or
12 mph in high range, the driver would lift his/her foot off the
accelerator. After a few seconds, a 'clunk' would be heard (Chrysler called
it a 'click', but it was definitely a 'clunk') and the car was in high gear.
The driver then resumed speed. The unit would automatically downshift when
coming to a stop.
It was called Vacamatic by Chrysler in the U.S. 1941-42, Simplimatic by
DeSoto (1941-42) and Chrysler (CDN) 1941-42.
After the war the vacuum controls were replaced electric and hydraulic
controls and became Prestomatic by Chrysler (Fluid Matic in 1951) and
Tip-Toe-Hydraulic Shift by DeSoto. Dodge introduced its version in 1949 as
Gyromatic.
These three sem-automatics were also used with Fluid Torque Drive.
Hy-Drive came only with a 3-speed manual transmission, just as the basic
Fluid Drive did.
Chrysler's 2-speed Powerflite was introduced mid-year 1953 on the Chrysler
Imperials and on the rest of the Chryslers and the DeSoto by years end.
With Dodge adopting Powerflite for 1954, the end of the road was reached for
Fluid Drive, Fluid Torque Drive and the 4-speed semi-automatic, Powerflite
was introduced on the Plymouth in mid-1954 and Hy-Drive was dropped by the
end the year.
And that was why your grandmother's 1951 Dodge with Fluid Drive and a
3-speed transmission was so easy to shift. The Fluid Drive prevented the
car from stalling even if the car was in gear when you came to a stop and
also made the shifts between gears smoother as well. The car was also more
sluggish due to the fluid coupling, mind you..
Bill
Vancouver, BC
----- Original Message -----
From: tom taylor
To: L-FORWARDLOOK@xxxxxxxxxxxxx
Sent: Sunday, July 30, 2006 3:38 AM
Subject: [FWDLK] fluid-drive hydro-matic three speed transmission
I had an easy time as a early teen learning to drive a "straight stick"
because my grand mother had a 1951 Dodge with the above tranny and clutch
configuration. I did not know this at the time. When she bought a 1960
Valiant, her first purchase of a new car, I then learned about really
clutches and shifting.
I never really understood this particular transmission configuration and
would appreciate one of the list experts throwing some light on it.
Thanks.
Tom Taylor
1955 Coronet (powerflite so no issue with shifting)
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