So I've got about 1000 miles on my 4l60 in my turbo 03ecsb z71. I just rebuilt my trans about 1k ago and it was shifting excellent and I took off from a light the other day and when it shifted into second it was a really soft more of a slip into second. It had previously been very firm. Third is fine and obviously with lack of second there is no fourth. I'm wondering about the second gear accumulator or spring, any other ideas

 

The band might of burnt up. I had a similar issue just didn't have 4th. And it was the band I believe

 

Check servo apply pin. Pry on servo cover with pry bar and socket and watch how much cover pushes in before it stops. Should be approximately half inch. This may tell you if your band is applying or maybe it broke off locator pin. If it gradually went into 2nd as you described vs. firm I'm wondering more so if it just went right into third cause trans saw it wasn't making 2nd gear ratio. And then that would help explain also no 4th.

Oh and also check the 1-2 accumulator too. Make sure that plastic piston didn't crack. Let me know what you find with these and I'll help you with more.

 

I have a metal accumulator piston its fibe the band broke off where the servo pin pushes on it. I've hot pics but not sure how to post

 

What brand/kind of servo do u have in it?

 

Good find. It's rare to see bands break there but I have seen it even in stock form vehicles.

 

I havea billet super servo