Here is whats going on. I have a built 4L60E trans (shift kit,racing clutchs/kollen steels, upgraded sprag, beast sunshell, Billet accumulator piston, corvette servo,3-4 wide clutch band) with a 3200 FTI stall. I have put around 800miles on the trans. I went to the track recently and when the car shifts from 2nd-3rd gear under WOT it hits the rev limiter for a split second before catching 3rd gear. I tried it on the street and it does the same thing. I am wondering if anyone else has experienced this and could help out. The car is a basic bolt on car with a built 10bolt w/3:73 gears. Thanks in advance for the help.

 

The 2-3 shift is the slowest on a 4L60E so just set the shift 100rpm sooner or raise the limiter a tad

 

Thanks flame! Thats what i figured and i was just making sure thats what the issue was. Thanks again!

 

It can be tune related and it can also be a mechanical calibration in the transmission.
The transmission applies third and releases second during the 2-3 shift.
Several things can cause what you said is happening. Servo travel, 3-4 clutch clearance, third apply feed hole size compared to the band release feed hole size which is altered with the shift kit.