General Information
31TH TRANSAXLENOTE: Safety goggles should be worn at all times when working on these transaxles.
This transaxle combines torque converter, three speed transmission, final drive gearing, and differential into a front wheel drive system. The identification markings and usage of the transaxle are charted in Diagnosis and Tests.
NOTE: Transaxle operation requirements are different for each vehicle and engine combination. Some internal parts will be different to provide for this. Therefore, when replacing parts, refer to the seven digit part number stamped on rear of the transaxle oil pan flange.
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.
4. Center distances between the main rotating parts in these three areas are held precise to maintain a low noise level.
5. 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.
6. 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.
7. The transaxle fluid is filtered by an internal filter attached to the lower side of the valve body assembly.
8. Engine torque is transmitted to the torque converter then, through the input shaft to multiple-disc clutches in the transaxle. The power flow depends on the application of the clutches and bands.
9. 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 drive 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 of the 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. The final drive gearing is completed with one of two gear ratios of 2.98 or 3.19 depending on model and application.
FLUID LEVEL AND CONDITION
NOTE: The transmission and differential sump have a common oil sump with a communicating opening between the two.
The torque converter fills in both the P Park and N Neutral positions. Place the selector lever in P Park to be sure that the fluid level check is accurate. The engine should be running at idle speed for at least one minute, with the vehicle on level ground. This will assure complete oil level stabilization between differential and transmission. The fluid should be at normal operating temperature (approximately 82°C or 180°F). The fluid level is correct if it is in the HOT region (crosshatched area) on the dipstick.
Low fluid level can cause a variety of conditions because it allows the pump to take in air along with the fluid. As in any hydraulic system, air bubbles make the fluid spongy, therefore, pressures will be low and build up slowly.
Improper filling can also raise the fluid level too high. When the transaxle has too much fluid, the gears churn up foam and cause the same conditions which occur with a low fluid level.
In either case, the air bubbles can cause overheating, fluid oxidation, and varnishing. This can interfere with normal valve, clutch, and servo operation. Foaming can also result in fluid escaping from the transaxle dipstick where it may be mistaken for a leak.
Along with fluid level, it is important to check the condition of the fluid. When the fluid smells burned, and is contaminated with metal or friction material particles, a complete transaxle overhaul is needed. Be sure to examine the fluid on the dipstick closely. If there is any doubt about its condition, drain out a sample for a double check.
SELECTION OF LUBRICANT
It is important that the proper lubricant be used in these transmissions. MOPAR ATF+4 (Automatic Transmission Fluid- type 9602) should be used to aid in ensuring optimum transmission performance. It is important that the transmission fluid be maintained at the prescribed level using the recommended fluids.
SPECIAL ADDITIVES
Chrysler Corporation does not recommend the addition of any fluids to the transmission, other than fluid listed above. An exception to this policy is the use of special dyes to aid in detecting fluid leaks. The use of transmission sealers should be avoided, since they may adversely affect seals.