A604/41TE Chrysler FWD 4-speed Automatic Transaxle Information
Many times, a transaxle that the dealer or transmission shop says is "not repairable" can be fixed with the simple steps outlined here. Don't give up hope just because a mechanic or two says your transaxle needs to be replaced. Many transaxle problems can be cured by changing the fluid and retraining the computer.
When you change your transmission fluid, always use the recommended fluid. For 1995-1999 models, it's ATF+3. For 2000 and newer models, it's ATF+4. Don't mix and match - the fluids don't play well together.
Don't just assume your mechanic or dealer knows what fluid to use - ask and make sure it's the right one. If they do not or cannot provide the correct fluid, then go somewhere else that does.
Several companies now sell "universal" fluids, often using a synthetic base, which they say will work with just about all vehicles. If they note that they are compatible with ATF+3 and +4 - and most do - they may work well, especially for those unsure of which fluid to use. Valvoline MaxLife appears to be a suitable alternative to factory ATF+3.
If you suspect that Dexron has been put into your A604/41TE, invest the $40 or so to have it replaced immediately Dextron is a "grabbier" fluid - the A604/41TE is designed to slip a bit during shifts - and ultimately it'll cause the transaxle to fail.
Ask your dealer about updated firmware for the transaxle control module (TCM) - changes are made from time to time that can eliminate or reduce problems such as "bump-shifts" or a shuddering torque converter. Some dealers are better at this that others - some may do it for free - others may charge for it. Call around.
Common failure points include the speed sensors - both input and output - and the solenoid packs. The solenoid packs can become clogged - especially if the wrong fluid is used. Failure of the speed sensors can trigger "limp mode" which causes the transmission to only use first and second as a very visible sign that something is wrong. You should be checking the computer for error codes at this point.
Information provided by Steve "SANDMAN" Martinez of Exile Racing Technologies ...
This should help you understand some of the problems and inner workings of this slushbox. We (ERT) have been testing them to see what they can actually handle and are still in the first stages of these tests. I'll do another writeup on that later. I don't want to get too in depth with this because frankly with would be a novel.
The A604 is the Achilles heel of these cars and everyone knows it. They break under stock conditions, and they break under moderate engine mods. In some cases they explode, and it has less to do with power and more to do with design. When properly built, the trans can handle a decent amount of power input, but it is important to keep up with maintenance and get the build done by a reputable shop. We'll outline some of the major problems in dealing with the A604 and the ways to counteract or alleviate those problems all together.
The first and most frequent killer of ANY transmission is heat. When you are putting power to the transmission, clutches create a ton of heat. This in turn breaks down the transmission fluid causing accelerated wear on the clutches, seals burn out, and you're in for a big bill. Transmission fluid generally starts to break down at about 240F degrees that is when the fluid starts to get thick and varnishes. This clogs and sticks in passages or clutches and prevents parts like the solenoid pack from doing a good job of shifting gears. At around 265F degrees or so, you get to the threshold of the seals. They can only take so much heat and at this temp they start to get rigid thus creating internal leaks. Internal leaks cause loss of line pressure, and when you have poor line pressure holding a gear is harder. The clutches aren't pressed to the steel plates hard enough and they wear faster; you'll notice your fluid turning brown or potentially black if it's severe. At 300F degrees your fluid is so bad; the clutches start to slip more often. This refuse can cause clogged filters, and clogged ports on the shift solenoid. Heat starts to build even more and once you hit 315F degrees your seals burn out, clutches are burned out, and you build up a nice concentration of carbon filled gritty fluid. How do you prevent this? You probably already know the answer to this, but it with an aftermarket inline cooler. The stock system has a cooler built into the radiator, but it is small and is highly inefficient. Most people pick up the popular line of B&M Super Coolers. They work great and you can run them in tandem with the stock cooler for even more efficiency. Truth is any 6-pass cooler will work, and do the job perfect. There is such a thing as TOO BIG when it comes to trans coolers though. If you run say a 10-pass cooler in tandem with a stock cooler and leave for work on a cold morning. You'll notice your car is holding second gear a lot longer than it usually does. This is the trans going through a warm up mode trying to get the fluid to optimum temps for operation. It's not bad for the trans per say, but it's annoying if you hit the gas and it sticks in gear and then pounds into third gear. The temps you want to stay around are 185-200 degrees, those are optimal temps for good life of the trans and better power transfer.
The second most frequent problem is the differential idler shaft. I myself have been victim to this little chunk of hatred, and it almost cost me a car. The idler shaft is a round chunk of metal a little over ½ inches in thickness. This shaft sits inside the idler gears which in turn rotate the spider gears in the differential. This shaft is held in by a pin which from the factory is pressed in, and then the surrounding differential carrier material is pinched over it to attempt a lock on the pin. The shaft itself does exactly as it says and remains idle holding the gears in alignment in the carrier. There are many ways for this part to fail, a lot has to do with oiling and leads us back to the cooling. The shaft sits static, while the spider gears turn the idler gears which rest on this shaft. The speed as you can imagine is high and if no oiling is poor the heat builds and those gears weld themselves to this shaft. This causes catastrophic failure and generally leads to the shaft snapping and going through the case of the transmission. Heat is probably a part of nearly all the failures in the transmission. Doing one wheel burnouts in parking lots causes' heat and also forces the gears and shaft into an uneven balance. When you are spinning that one wheel, the gears can come out of their alignment and start to bend and grind on that shaft. This creates shrapnel and in turn goes parading through your trans clogging and cutting seals as it goes. If this doesn't kill the differential, the retaining pin will. This little piece of metal is responsible for hold that shaft from going out of carrier, and from rotating with the idler shaft. If this pin were to come out, you guessed it. If the shaft seizes on the idler gears, it will tear that pin off and then the party begins. How do you fix ALL of this? There is no bulletproof way to do it in the A604. Companies like Quaife or Kaaz manufacture differentials that are nearly indestructible and if they do blow they'll replace it. I myself have never seen one fail, so if you have that available in your model trans I envy you. Now, for us poor A604 owners with no Quaife option, there are a few alternatives.
Now we get into the internal parts of the transmission, the guts. Say your trans is going or you plan on putting some decent power through there and want to be safe. Time to rebuild with some beefy parts you say, but don't know where to start or what to look for. I'll lay out the parts I look for in a performance build, and also explain why I chose these parts.
Now that you have your new trans, you have to take care of it. Maintaining a built trans is the same as maintaining your stock trans. Only use Mopar 7176 trans fluid or approved ATF+3. You can switch to +4, but the cost is higher and finding +4 anywhere but a dealer is a chore. (Cars built in 2000 and newer use ATF+4 direct from the factory.) Change your filter every 30-40K and make sure to get the correct year and model for your car. I use the dealer for this because the OEM replacement works best. While you are there ask for Mopar Anti-Foam. This little bottle gets poured into your transmission and prevents foaming of the fluid. Bubbles compress and you have bad line pressure; this eliminates bubbles. Caring for your transmission takes only a few minutes each time and saves you money in the long run. If you take care of it, it'll take care of you.
Steve "SANDMAN" Martinez