The inner workings of the A-727 Torqueflite transmissions
Chrysler's A-727 Torqueflite transmissions are an automatic three speed transmission.
Chrysler's Torqueflite's are a one piece aluminum case.Simpson Type planetary gears set, also a gerotor style pump.
Cast in one piece is the case and bell housing, with a variety of bell housing configurations to except the three engines. (A, B/RB, and six cylinder).
The 727 Automatic transmission operates on basic hydraulic and mechanical principles. When tackling the rebuild of a 727 automatic transmission, one needs to be well-versed on the inner workings and basic principles of a transmission.
The Chrysler A-727 Torqueflite Clutches
The front clutch has Three, Four, or Five friction clutches and three steels.
When the low and reverse band is applied at the same time it will provide reverse.
When applied simultaneously with the rear clutch it will then provide you High Gear.
The rear clutch has four friction clutches and three steels.
The rear clutch is applied whenever the vehicle is moving forward.
When applied at the same time with the low and reverse band provides manual low.
When applied simultaneously with the kick down band, it provides second gear, when applied simultaneously
with the front clutch it provides high range, when applied simultaneously with the rear
overrunning clutch it will provide breakaway low.
Chrysler's A-727 Torqueflite transmission components
Kick down Band:
The Front band in the transmission is the Kickdown band.
Low & Reverse Band
The rear-most band in the transmission are the low & reverse band. The low and reverse band is applied when the gear selector is placed in reverse or manual low.
When applied it holds the low and reverse drum motionless.
The Overrunning Clutch of A-727 Torqueflite
The overrunning clutch will be located at the rear of the case.
The overrunning clutch will be applied when the gear selector is placed in drive, and the car is sitting still. it will stay applied in the breakaway low, it is also applied when the trans downshifts automatically from second to low.
If the gear selector is in park, there will be no friction elements engaged.
A rod connected to the manual valve assembly on the valve body engages a pawl that in turn engages a notch on the outside of a flange that is splined to the output shaft.
This will lock the flange to the transmission case, holding the vehicle still.
If the gear selector is in Neutral, no friction components are in use.
Low ( Manual )
If the gear selector is placed in "low" the rear clutch & the low/reverse band are applied. The rear clutch rotates the front annulus gear and front planetary gears clockwise. This turns the sun gear counterclockwise.
The low reverse bands hold the low reverse drum motionless.
If the gear selector is placed in "second" the rear clutch and kick down (front) band are applied. The rear clutch applied causes the front annulus gear, and front planetary gears to rotate clockwise.
The formula to calculate the second gear ratio is the following:
Second Gear Ratio 1 + Teeth on Sun Gear/Teeth on Ring Gear
= 1 + 28/62
= 1 + .45
DRIVE ( High ):
If the gear selector is placed in "Drive", high gear, the front clutch and rear clutch are applied. If both clutch packs are applied, the front planetary gears will not rotate.
This will cause the front planetary cage to turn the output shaft at input shaft speed providing high gear.
If the gear selector is placed in reverse, the front clutch and low/reverse band is applied.
Applying the front clutch causes the sun shell and, therefore, the sun gear to rotate clockwise.
The formula, for determining the reverse gear ratio is:
Reverse gear Ratio= Teeth on Ring, Gear/teeth on Sun Gear