The Fordomatic automatic transmission used in the Ford Falcon XK combines a hydraulic torque converter with a planetary gear system to provide smooth automatic operation. This design allows the transmission to deliver two forward driving speeds and one reverse gear while automatically selecting the appropriate gear based on vehicle speed and throttle position.
The planetary gear system functions as a compound gear set. One clutch and two bands provide the two forward gear ratios and reverse operation. Hydraulic control within the transmission determines gear changes and ensures smooth engagement during acceleration and deceleration.
Selector Lever Positions
The transmission selector dial provides five operating positions:
P – Park
R – Reverse
N – Neutral
D – Drive
L – Low
The engine must be started with the selector lever in either the Park (P) or Neutral (N) position.
When the selector lever is moved from Neutral or Park into the Drive (D) position, the transmission engages first gear and the vehicle begins to move forward.
Automatic Gear Changes
In the Drive position the vehicle always starts in first gear. The transmission automatically shifts from first gear to second gear depending on vehicle speed and throttle position.
The first-to-second gear shift normally occurs between approximately 10 and 48 miles per hour, depending on accelerator pedal position and engine load.
When the vehicle slows during deceleration, the transmission will automatically downshift back into first gear at approximately 9 miles per hour.
Forced Downshift (Kickdown)
A forced downshift from second gear to first gear, often referred to as kickdown, can occur when the accelerator pedal is pressed rapidly while driving at lower speeds.
This forced downshift is possible at vehicle speeds below approximately 47 miles per hour and provides increased engine power for acceleration.
Low Gear Operation
When the selector lever is placed in the Low (L) position, the transmission remains in first gear regardless of vehicle speed or throttle position.
This position is typically used when additional engine braking or maximum pulling power is required.
To prevent excessive engine speed, the transmission should not be shifted into Low at speeds exceeding the normal automatic shift point.
A gate-type stop is installed between the Drive (D) and Low (L) positions to prevent accidental shifting into Low gear. To move the selector past this stop, the shift lever must first be lifted toward the steering wheel and then moved downward into position.
Reverse Gear Operation
Reverse gear is selected by moving the selector lever to the Reverse (R) position.
A similar stop mechanism prevents accidental engagement of reverse while driving. The transmission does not include an automatic inhibitor for the Reverse or Low positions, meaning these positions can be selected at any speed. For safety and to prevent transmission damage, reverse gear should only be engaged after the vehicle has come to a complete stop.
Park Position
When the selector lever is placed in the Park (P) position, a mechanical pawl locks the transmission output shaft to the transmission case.
With the output shaft locked, the rear wheels are prevented from rotating, effectively securing the vehicle when parked.
Torque Converter Operation
The torque converter is responsible for transmitting engine power to the transmission while allowing the engine to continue running when the vehicle is stationary.
The converter consists primarily of an impeller, turbine and stator assembly contained within the converter housing.
Engine rotation drives the impeller, which circulates transmission fluid against the turbine blades. The moving fluid causes the turbine to rotate, transmitting power to the transmission input shaft.
The stator redirects fluid flow to increase torque multiplication during acceleration, improving vehicle performance when starting from rest.
Planetary Gear System
The planetary gear system provides the mechanical gear ratios required for vehicle movement.
This gear system consists of a sun gear, planetary pinions and ring gear. Through the controlled application of clutches and bands, the planetary gear set provides the different gear ratios required for forward and reverse operation.
The combination of the torque converter and planetary gear assembly allows the Fordomatic transmission to shift automatically without driver intervention.
Transmission Identification
Each Fordomatic transmission is individually identified by a stamped number located on the right-hand side of the transmission case above the filler tube fitting.
This identification consists of a serial prefix followed by a serial number and engine application designation. The prefix identifies the transmission model, while the serial number sequence begins at 10,001.
The number stamped below the serial prefix indicates the engine displacement for which the transmission is calibrated.
Fordomatic Automatic Shift Speeds
Approximate automatic shift speeds for vehicles equipped with a 3.56:1 rear axle ratio are as follows:
First to second shift at minimum throttle occurs between approximately 10 and 16 miles per hour.
With increased throttle and through detent operation, the shift may occur between approximately 44 and 48 miles per hour.
During deceleration, the transmission will shift from second back to first gear between approximately 40 and 47 miles per hour, with closed throttle downshifts occurring between approximately 7 and 12 miles per hour.
These values may vary slightly depending on vehicle condition, throttle position and load.
Safety, Copyright and Source Notice
Safety Disclaimer
Working on motor vehicles involves mechanical, electrical and chemical hazards. Always ensure the vehicle is safely supported, the engine is switched off when appropriate, and suitable safety equipment such as gloves and eye protection is used. If you are unsure about any repair or maintenance procedure, consult a qualified mechanic before attempting the work.
Source
Information compiled from period factory shop manual.
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