The transmission itself is not "weak" nor does the fluid overheat in the traditional sense. The main problem with this transmission is that the pump is weak, especially after it has miles on it and line pressure is too low to properly hold the high clutch together. It is most prononuced in the SVX model because of a combination of the deep final drive, weight of the car, and high torque of the engine. It has been hypothesized by some of us who have spent a lot of time with the 4EAT that relatively low vehicle speeds and low load, the high clutch is slipping due to this low pressure. This is further aggrivated by the logic in the TCU that reduces line pressure during 3-4 shift to make it smooth.
This is the only problem that could not be solved with the numerous updates to the transmission, and it is my opinion that a combination of A high performance transmission pump and a modified valve body will help keep the high clutch from slipping, and this is one of the major key areas adressed when this transmission is rebuilt by members here or by a reputable transmission shop. Another step which should be coming soon is a change to the transmission control unit so that it does not reduce pressure at this critical time.
Cooler selection must be done carefully because of the way the cooler circuit is arranged internally in this transmission. A cooler that is too restrictive will cause a partial bypass of the circuit inside the transmission. All of the popular hayden models that people are putting in front of the radiator are too restrictive, some are not much better than the radiator cooler itself. A cooler restriction can cause major damages to the transmission hard parts.
The best choice for a cooler is the high flow unit I have installed on my vehicle as it is not restrictive at all and contains a thermostatic fan which fights to keep the pan temperature at a close to ideal 150-160f. This should be installed in place of the stock unit which is best left unused, especially if it is one of the older cars that still has the original radiator, which contains a screen to promote heat exchange that becomes clogged due to the desentegration of the torque converter clutch found on early models.
See
http://www.subaru-svx.net/forum/show...mission+cooler for info on the cooler.
P.S. I love having pre written posts stored in my email
