Rebuilt this 4l60e last week... test drove it around the neighborhood for about 20 mins, everything was good... peppy, shift up thru all gears, locks up and everything is cool... the next day, i drove it around for a little bit... maybe about 40 mins... at some point it stopped going to 4th gear... i leave it alone for a couple days, go thru the forums and research some stuff... pointing to servo... i got a corvette servo, whole deal, came with the pin and the pistons and a red cover... all set up, plug and play basically... i lubed it up and installed... didnt really much look at it apparently, cuz the 4th gear piston was installed backward... flipped it around and took it back out for a test drive, and it seemed to be ok... good strong shifts for another 20 mins or so, then no 4th gear again... it locks up at low speeds, 30 or so, when im in the neighborhood... but if i go above 40, its the same as a 3 speed... my question is this... does this sound like im not getting enough apply pressure from this servo, or does this sound like possibly a check ball is blown through and the pressure is bleeding off? The whole reason i rebuilt is because after putting a new pump and converter, my reverse was doing the same thing... now my reverse works all the time it seems, but my 4th gear is bleeding off... 🤷‍♂️🤔 ​​​​​​​i used some of those valve body repair deals (fitzall vb101) but theres only 5 in the pack... what i think is i drilled a hole that i then didnt have a detent for, and its causing me to have intermittent issues... any input from someone who knows this trans would be cool... im not a "trans guy" i just really went to town on this one and i want it to be fixed finally...

 

Ive only put 40 or so miles on this thing since the rebuild... all test drive miles... and like i said, when i set out (cold) it has all the gears and locks up (stays locked up until brake or hard accel) but then after a little bit it goes 3spd on me

 

Just to follow up, since nobody wanted to put any info up... i had an issue with one of my checkballs blowing thru the separator plate... new separator plate and it was fine... i did throw a new valve body with a couple shift kits in it... now it hits like a ton of bricks... firm 2nd shift, chirps on the shift if u stay on the gas... pretty bad ***... if ur in chicago, see justin at total transmissions chicago, in bellwood... guy hooked me up hard