31TH

AUTOMATIC - 31TH
DESCRIPTION
This transaxle combines torque converter, three speed transmission, final drive gearing, and differential into a front wheel drive system.
Within this transaxle, there are three primary areas:
1. Main center line plus valve body.
2. Transfer shaft center line (includes governor and parking spray).
3. Differential center line.
Center distances between the main rotating parts in these three areas are held precise to maintain a low noise level.
The torque converter, transaxle area, and differential are housed in an integral aluminum die casting. The differential oil sump is common with the transaxle sump. Separate filling of the differential is NOT necessary.
The torque converter is attached to the crankshaft through a flexible driving plate. Cooling of the converter is accomplished by circulating the transaxle fluid through a remote cooler. There are two types of coolers used. An oil-to-water type cooler located in the radiator side tank and/or an oil-to-air heat exchanger. The torque converter assembly is a sealed unit that cannot be disassembled.
The transaxle fluid is filtered by an internal filter attached to the lower side of the valve body assembly. Engine torque is transmitted to the torque converter and then through the input shaft to multiple disc clutches in the transaxle. The power flow depends on the application of the clutches and bands. Refer to Elements in Use Chart in Diagnosis and Tests.
The transaxle consists of:
- Two multiple-disc clutches
- An overrunning clutch
- Two servos
- A hydraulic accumulator
- Two bands
- Two planetary gear sets
This provides three forward ratios and a reverse ratio. The common sun gear of the planetary gear sets is connected to the front clutch by a driving shell. The driving shell is splined to the sun gear and front clutch retainer. The hydraulic system consists of an oil pump and a single valve body, which contains all of the valves except the governor valves. The transaxle sump and differential sump are both vented through the dipstick. Output torque from the main center line is delivered through helical gears to the transfer shaft. This gear set is a factor in the transaxle final drive (axle) ratio. The shaft also carries the governor and parking spray. An integral helical gear on the transfer shaft drives the differential ring gear.





31TH AUTOMATIC TRANSAXLE

OPERATION
Transmission output is directed to an integral differential by a transfer gear system in the following input-to-output ratios:

GEAR RATIO
FIRST 2.69:1
SECOND 1.55:1
THIRD 1.00:1
REVERSE 2.10:1