From Dsmwiki
Information
The second generation non-turbo Eclipse/Talon not only introduced a Chrysler engine to the mix 1995, but with also included two different Chrysler transaxles as well. The automatic transaxle will be discussed here.
The automatic transaxle found in 2gnt's is referred to by Chrysler as the 41TE or A604, and by Mitsubishi as the F4AC1.
The term "transaxle" is used to for cars with a transversely mounted engine where the transmission incorporates a differential inside the transmission to make this vehicle front engine and front wheel drive.
The 41TE transaxle used in 95-99 Eclipse/Talon vehicles has been in use since at least the early 90's. The higher line Chrysler minivans as well as Dodge Dynasty/New Yorkers also ran this trans.
The transaxle uses ATF+3 (superceded by ATF+4) transmission fluid, RTV or re-usable gasket for the transmission pan, plastic filter with filter element inside, a transmission oil cooler located in one of the end tanks of the coolant radiator, an input speed sensor, an output speed sensor, transaxle solenoid pack, a torque convertor, and a group of clutches.
The torque converter employed by Chrysler is 9.5", (241mm) electronically locking, and has a 2.65 stall ratio.
Common mistakes made on these type of transaxles may include the use of Dexron III or other automatic transmission fluids that are not recommended, lack of fluid and filter change (every 20,000 miles at least), and electronic component failure being misdiagnosed as internal transmission failure.
The transmission gearing is electronically controlled by the transmission control module (TCM or TCU)) located behind the radio. The TCM and powertrain Control Module (PCM or ECU) work together to analyzing engine load, throttle position, RPM, vehicle speed, and several other factors to determine which gear to put the transmission in to. The transmission solenoid pack, located underneath the oil cooler lines on the transmission, is responsible for controlling the flow of transmission fluid to various passages. Each passage builds and drops pressure inside the transmission to upshift, downshift and maintain vehicle speed. Vehicle speed is calculated by information fed to the computers from the input and output speed sensors. The Input speed sensor is located underneath the oil cooler lines and just above the transmission solenoid pack. The output speed sensor is located closer to the left front wheel area of the transmission. Both input and output speed sensors (VSS) look identical until removed, where one has a tip on the end while the other is flat.
The output speed sensor is responsible for indicating vehicle speed which the TCM monitors, as well as the driver with speed information being displayed by the speedometer.
The TCM has a safe mode that it goes in to when it detects a fault in the system. This mode is referred to as "Limp In". Basically, anytime there is a transmission related fault code the computer commands the computer to stay in second gear only. The gearing for second is such that it will allow the driver to accelerate from a stop without bogging out as well as maintain speeds up to around 45 mph. This enables the driver to drive the car until out of harms way as well as possibly make it to a repair shop. In order to remove the TCM from "Limp In", the DTCs (Diagnostic Trouble Codes) have to be erased. This can be done by removing the fuse labelled "Engine" in the power distribution center (PDC) which is the fuse and relay block next to the battery. Otherwise, the DTC's have to be removed with the use of a scan tool. Some generic scan tools are not capable of reading any TCM information or TCM specific codes. If there are any TCM DTCs, the PCM will have code P0700 TCM DTCs Present.
As with many transmission there are after-market components that can be installed to enhance performance. There are shift kits, torque converters, and a final drive (side gear) modification available. Extreme care should be taken when introducing these components in to this transmission. Observe valve body torque specs, transmission fluid volume and type specs, and do not perform any upgrades on a transmission that is already having problems.
The final drive modification uses pieces from the Chrysler parts bin. It is quick, cheap and easy to do. The end result is a slightly quicker launch with minimal loss of top speed.
These transmissions, with proper maintenance and wise modification selection can make it worth keeping in the car for a while. It is cheaper to maintain it then it is to swap or replace it.
One last note on transmission fluids. In the last two or three years Chyrsler introduced another "ATF+" fluid. This fluid is ATF+4. It's characteristics are similar to +3 and +4 can be used in the 41TE however, once the fluid use is upgraded to +4, you should not go back to using +3. However, it is referred to as a "fill for life" fluid. It is more expensive and synthetic. The lifespan of this fluid is, according to Chrysler, supposed to last the life of the vehicle. Please note that the transmission filter will still require replacing at scheduled intervals, and thus the fluid as well.
How It Works
The transmission has multiple clutches in it. Low-Reverse share a clutch pack, 2-4 share one, there's underdrive, and there's overdrive. That's four different sets of clutchs inside the transmission. Each clutch is designed to have a certain amount of clutch material on it. These clutches are covered in transmission fluid. The amount of transmission fluid needed to fill up each clutch pack is referred to as it's CVI (Clutch Volume Index). As the clutches wear out the amount of fluid needed to compensate for clutch wear increases.
Essentially, there is a computer that measures clutch thickness (based of volume needed to fill a void) as well as one that can compensate for clutch wear. This is good because as a transmission is driven, wear is a normal result of use. A transmission that does not compensate for this wear means harsher and harsher shifts, trembling when going in to gear, and poor engagement in to gears.
The down side of this would be that once the transmission starts exhibiting these harsh shifts, trembling when shifting or going in to lockup or lac of acceleration, the clutches are near the end of their life and the problem should be dealt with right away. The wear is at a max and continuing to drive the car will only result in damaging other components that otherwise could be salvaged during a rebuild.
Change the transmission fluid and filter every 15-20,000. Have the CVI's checked by the dealer to make sure they're within tolerance, and if they're out of spec, baby the car and save up some money for a rebuild, or possibly a 5-speed manual swap.
Original tech article by Doug99RS.
--Locke 02:49, 30 December 2007 (EST)
DSMwiki Index
