8L90E Harsh Clunk Into Reverse

[BernTheMars]

I have a 2016 Silverado Z71 with the 8l90e trans. Ever since i got it, there has been a little bit of clunk going into gear from park. No biggie. However, I recently installed a SuperLift 3.5" kit and had the battery disconnected for about 8 days. When i turned on the truck finally, i noticed that the temperature was wrong and the compass needed calibration so i drove it and it sorted itself out. Truck rides great. No vibration and no weird noises EXCEPT for the fact that i now get hard clunks going into reverse 8 times out of 10. I have narrowed it down to either the transfer case or the transmission itself. Could the transmission programming have been altered? Its had a dead battery before but have not experienced this issue before. Like i said before there are no vibrations, clunks, or noises while driving at all, just when shifting from park. Anyone have any idea what could be going on?

[Ltz4 me?]

I've had mine into dealership and have been told "that's just how these transmission shift" no matter what issue I have with it, that's there answer to me...( Last week he said I should just traded mine in on a new one b/c they have no issues!)

I told him I paid for a extended warranty to cover my ass incase tranny fails and I'm never buying another chevy again.

He really showed no sign of any kind of a reaction or care( what they don't realize is how many people aren't happy b/c he went on further to tell me) " we really don't replace many of the m5u tranny's here or have any problem s with them" B.S!!!

I wish gm would replace them with a better tranny b/c it's a great truck otherwise ( I'm in talks now with blackbear tuning for a hope on my part they can make this truck drivable and smooth it out)sucks I'll need to spend so much on it to do this but dealership won't do anything unless something is throwing a code or literally broke/ not moving anymore.

Other thing I thought of doing is trying a different dealership to see if they will do anything with these tranny's that are known to have deflect s(m5u)...