Thread: 4T65E Hard Shift-Solution

Originally Posted by frugal

Hard shift update Finally!
Upon reading jmamonte"s post, i concluded that I was willing to give this a try. I ordered the kit from ZZ Performance, then became bogged down with other life's issues, I finally installed the kit and have no more Hard-shift. It does shudder shift 1-2 when hot, but this is usually when the hard shifting would start. I had previously installed a small stacked plate cooler and am contemplating buying a larger one with a fan. I wish I knew how to over ride the cooling fans to turn on earlier, I think they are programmed to turn on at 230'F. ( any Ideas?) Maybe I'll just do a full overrideso their always on. So those trannys run HOT!!! And the hard shift issue only occurs when hot! I know that I am only buying myself some time before a rebuild. I had recently done a service and am using transynd ATF fluid (Good stuff thanks Allison!) Thanks Jmamonte your posts just bought me some valuable time. I was actually contemplating getting my wife a Toyota Sienna ( yuck). I'will give future updates as the ol Montana van is a real work horse, 232000 kms (145000miles) so we'll see how long this goes.

I installed 2 double stack 18,000 GVW tranny coolers one on each side under the bumper that do not run the transmission line through the radiator, the coolers do all the cooling. I choose that route since the radiator cooler will never get the trans fluid temperature lower than the coolant temperature which runs between 185-210 on my car on the gauge. I have not had a hard shift problem since the installation of the ZZP shift kit with the coolers since the fans run very often in the hotter weather with the A/C on and pull air over the cooler in the warmer weather. Obviously, winter driving is not a problem with the trans fluid running cool enough. I mounted the coolers in the grille above the lower bumper intakes and below the dual snorkel intakes up higher so you cannot see the cooler from the front of the car. I chose this location to protect the coolers from road debris and to lessen the cooling effect slightly in the extreme winter since they would not be exposed to direct cold air while the car was moving in the winter. The fans pull the air through the coolers in the summer with the A/C on. No issues in 6,000 miles of driving so far and the tranny shifts perfectly normal but my trans with 100,000 miles was not abused and the fluid was changed with filter 4X over its life. In my case with my setup and based on the condition of the tranny in general, I expect this setup will allow the transmission to run ten of thousands more miles with no problem from the hard shift issue as long as no other issues develop. Total cost for 2 Long double stack 18,000 GVW coolers and the ZZP shift kit was about $150. The coolers will also greatly extend the life of the tranny. I use Dexron VI and change the fluid every 20,000 miles or 3 years. Less is better!Hope that helps!