As all of you know, the 4T65E transmissions are notorious for dying in our cars, especially behind the 300+ horsepower 5.3L LS4 V8 (why in the world GM decided to put this transmission behind this motor is absolutely beyond me). I'm not a transmission expert by any means, however I usually do my own work on cars and have gained some knowledge over time from working on cars in general as well as general research. Below I have listed some things that I've personally found to be useful in helping our transmissions run a little better.
1. Consistent Maintenance
Obviously this one is kind of common sense. Better maintained parts tend to last longer. Changing transmission fluid and filter regularly is generally going to better the life of your transmission.
2. Upgrade Those Magnets!
From TSB: 08-07-30-040B. Many 4T65E transmissions were shipped with oil pan magnets comparable to nothing but your typical refrigerator magnet. These magnets become saturated very quickly and eventually will not even further catch and maintain metal shavings. When this happens, metal shavings cycling through the transmission will go to the PCS solenoid which is magnetic. This will throw off line pressure readings. Too low of line pressure will obviously cause slipping and/or delayed engagement (AKA slip and catch). The TSB for this service calls for the installation of TWO new, much stronger donut shaped magnets (part number 29535617). One magnet will be placed in the factory location on the oil pan and the other on the bottom side of the oil filter near the back of it.
3. Turn Up Line Pressure
The line pressure on the 4T65E transmission is set relatively low, for that smooth "luxury" shift. Lower line pressure results in more slipping and a "smoother" shift; higher line pressure results in less slipping and a firmer shift. Slipping is bad obviously, so if you want to extend the life of your transmission you need to eliminate as much slipping as possible. Line pressure on these transmissions is unfortunately controlled entirely by electronics, so you will need to buy a tuner or visit a tuning shop to turn up the line pressure on your transmission. Be careful though, too much line pressure can also do damage to your transmission.
4. Shift Kit
Shift kits are awesome!They firm up your shifts and make for a much sportier feel of the transmission. A shift kit can really bring a transmission alive! They help speed up and firm up shifts which results in less heat and more clutch life. Most of these kits can be installed by the average Joe with a couple of hours of free time on hand and can be bought for less than $100!
5. Change Your Converter Relief Valve
The converter relief valve has the job of bleeding off pressure so you don't engage the TCC with too much harshness. The factory converter relief valve is flawed in design in the sense that it bleeds off at too high of pressure. This results in faster wear and fail of the TCC which can show up later on as other problems.
6. TAPshift (If Applicable)
This goes in hand with turning up line pressure. TAPShift does more than just give you control of what gear you're in. TAPShift changes a lot of characteristics of the operation of your transmission when in use. One of these characteristics is line pressure. When using TAPShift, you will notice that your shifts seem firmer. That's because they are firmer! Line pressure is increased when TAPShift is in use and, as already explained, higher line pressure in generally a good thing for transmission life (within reason, obviously). I personally use TAPShift whenever I drive and I find that my transmission performs much better when using TAPShift rather than Drive.
7. Lucas Stop Slip (For Transmissions with Existing Problems)
I'm not typically a fan of the ole' "mechanic in a bottle" stuff that you see sitting on the shelves in AutoZone. Lucas Stop Slip on the other hand does have a proven track record of actually working, especially in our transmissions. If all else fails, try a bottle of this. A $10 bottle is cheaper than a $2000 rebuild and, hey if it buys you time to save up for a rebuild or new transmission then what else could you ask for?
If you have anything else to add to this thread. Feel free to do so! This is just a very minuscule amount of information out there on our transmissions and I just thought I'd share some of the knowledge I've gained through my research with y'all! Good luck to everyon
8. Aux. Transmission Cooler
Anybody who's switched their info display to show the transmission fluid temperature, especially in traffic or in the summer, may grow a little queasy watching those temps climb far past 200*F! Heat is the enemy! Any additional cooling help you can provide your transmission will be beneficial in its life length.
