Favorite Car with semi-automatic

["John G. Napoli" <john@xxxxxxxxx>]

There is also a difference between a fluid drive and one of the gyromatics/prestomatics we've been discussing.

 

A 'fluid drive' transmission is where you have a fluid coupling backed by a conventional clutch and a conventional three speed transmission.  My 49 Dodges have these trannys.  You need the clutch to shift gears.  You can come to a stop in any gear without declutching.  But, if you leave it in third, acceleration away from a stop is very, very slow.  Usually, you start out in second and use the clutch to shift to high.  First is rarely needed.

 

The Prestomatic/Gyromatic/Whatever-matics (semi-automatics) had the same fluid coupling and conventional clutch backed by a four-speed manual transmission with two ranges - low and high.  Each range could be shifted up or down one gear by a solenoid.  For normal driving, you put the lever in high range and release the clutch.  The car starts in third and when you release the accelerator you are in high.  Smae thing for first and second.  It is not possible to go thru all four gears without a lot of acrobatics (low range, start in ffirst, tranny shifts to second, use clutch to get high range but you're in high gear so must give full throttle and wait for kickdown to grab third, and then release gas pedal for fourth).  Whew!

 

It is incorrect to call the semi-automatic cars 'fluid drive'.

 

John

John:  Yes, but Plymouth's Hy-Drive bore no relationship to the semi-automatics.  It was a simple torque converter attached to a heavy-duty truck 3-speed transmission.  It also used a common oil pan between the engine and transmission.  Think of it as the old Fluid Drive with more "oomph."

Bob

 John Harvey <harvey5691@xxxxxxx> wrote: