trans kicking back?

[03f250stroke]

hey whats up guys? Im having this problem. Well I have had it happen 2 times. First time like a month ago and 2nd time was about 30 mins ago. I went out for a cruise meet up with some friends. We all left and my buddy has a 01 cummins so as usual we both took off. When I got off the throttle though, kind of like just left go of the pedal/let it out quick my Trans kicked back like really hard. My other buddies were still at the place that we hang out at and called me and ask if my trans fell out! It sounded like it hurt you know what I mean. It was loud and hard. I thought for sure my trans was gone. It drove totally fine on my way home so IDK what is going on or what happened?! The first time that it did happen was after I lifted my truck and I didnt have my driveshalf shims in yet. So I figured that it was because of that but since it just happened again I am totally stumped. I dont know how I can fix it or what is causing it. It really feel like there is more power/air in the motor and it just barks out but since Im not on the pedal the trans takes the abuse. If anyone else is dealing with something like or has ever had it happen please let me know what it is. I cant seem to figure it out. If its cause of the lift and the shims? or maybe my trans is going out, but then again I dont deal with any kinda of odd shifting out anything just firmer shifts especially when its cold from my SCT. Thanks alot guys hopefully someone can help me out!

[03f250stroke]

anyone out there...hello anybody

[DryHeatDude03]

What do you mean when you say it kicked back? I doubt its from the lift.

[sureshot8907]

i have a similar problem, though mine "kicks back" at the 1st to 2nd upshift. sounded like it fell out. recent rebuild on the tranny, and doesn't do it when it's cold? Maybe cheap fluid breaking down?

[03f250stroke]

kicking back, This is what we kinda came up with. Im driving the truck hard, Im running the RPMs up and then I just get off of it. But the computer telling the trans to shift but there is no pedal there so it just hits hard, like its shifting or something but really hard/firm. I dont think its from the lift either..and cheap fluid? maybe, could that be a problem?