Hello guys

My friends and I installed a new valve body because it was starting off in 3rd,
after the install it shifts so horribly into the next gear. What did I do wrong or what can I do to fix this?

 

Have you seen the manual for the Jatco 5AT? It's hundreds and hundreds of pages long. The mechanical programming of the transmission is so complicated I'll be shocked if anybody can help you figure that out that doesn't have professional experience with transmissions. Maybe a couple people here but not many and you'd probably need to be able to hook up pressure sensors to it like a transmission shop would to figure out what's going on. Going to be a tough one. I gained a great appreciation for how complicated it is to make that thing work as well as it does when installing a shift kit. All sorts of things to go wrong when you monkey around inside. That manual might give you some ideas how to troubleshoot. I don't remember really as it was years ago that I did the shift kit. Search around as it was available for free but I forget where I found it. If you can't find it, I'll dig around and see if I can find it in my files.