Thread: 4T65E Hard Shift-Solution

Originally Posted by jhs3eva

I am now 2,000 miles in. The van has been through plenty of all kinds of driving from around town to highway/rural highway 300 mile road trips. Much of this has been in very hot 90+ degree weather. After having the transmission act up almost every single time I drove it, it hasn't had any problem at all since installing the shift kit.

The time to install the cooler still eludes me. I just don't want to hurry it and do a hack job but I will be doing it. IMO the 2-3 shift is still a little weird sometimes, but only when hot and apparently not weird enough to trigger the code. The next time I drop the pan I'm going to put in the Transgo large 2-3 spring in place of the stock.

I'm really happy with all of this and am convinced that this is just poor GM design of this accumulator (though others might have the EPC solenoid problem).

Pretty hot up here in NE now and with the two 18,000 GVW coolers everything has been perfect on my tranny. When I put in the ZZP shift kit, I did not use the 3/4 inch spacer for the 2-3 piston as recommended but put in the 1/2 inch spacer like in the 1-2 piston. I too occassionally get a little strange shift on the 2-3 shift when the fluid is hot but only when the A/C is not on and the fans are not operating, pulling air over the 2 coolers. With the A/C running and the fans pulling air over the coolers continuously in very hot weather, zero issues and no harsh shift at all since the installation of the shift kit and coolers. I couldn't be happier with this fix!

I intend to install the 3/4 inch spacer on the 2-3 piston at the next fluid change to speed up the shifts on this piston a little more.

I would install the cooler as soon as possible and you should be good to go.