Transmission shifting badly

[Lrob4]

Hey all, this is my first time posting here so apologies if I’m posting in the wrong place. I have a 2019 Ram 2500 6.4 Hemi with the 8hp75 trans. It’s got 78k miles at the moment. Recently I’ve noticed it is shifting a little harder at cold and operating temps, and every so often mainly around 100 degrees trans temp, when I step on the gas as to get out in traffic, it will downshift, rev up and act like it wants to go, then clunk and fall to 2k rpms with no acceleration. This lasts about 1-2 seconds and then revs up and goes. It’s a little concerning. I have not had the service done on the trans yet. Any help appreciated. I have a video of it happening but I do not know how to link one.

 

[Gondul]

Hey all, this is my first time posting here so apologies if I’m posting in the wrong place. I have a 2019 Ram 2500 6.4 Hemi with the 8hp75 trans. It’s got 78k miles at the moment. Recently I’ve noticed it is shifting a little harder at cold and operating temps, and every so often mainly around 100 degrees trans temp, when I step on the gas as to get out in traffic, it will downshift, rev up and act like it wants to go, then clunk and fall to 2k rpms with no acceleration. This lasts about 1-2 seconds and then revs up and goes. It’s a little concerning. I have not had the service done on the trans yet. Any help appreciated. I have a video of it happening but I do not know how to link one.

ZF recommends filter/fluid change ever 80-120K kilometers (50-75K -ish miles)
I'd start by getting that done first... I just did mine.
As I'm out of warranty, I'm just going with AMSoil Signature Series Fuel-Efficient Synthetic ATF.

No need to level the transmission case per the email I received from ZF... just make sure the truck is level.
The green sheet lays out the steps a bit easier and there's plenty of time to top off the fluid before it hits temp... just try to do the change on a cooler day.

Thread 'ZF Fluid change on 2019 2500 6.4'

Oct 30, 2025

Changed the transmission fluid @ 72K miles.
Minimal towing of the TT so I was ok with waiting this long.

Picked up a MOPAR filter as it came with new hardware (also had 4 magnets) and I couldn't really find a solid/consistent review on the Dorman (which apparently can have only 2 magents), wasn't interested in a metal/bigger pan.
Used AMSoil Signature Series Fuel-Efficient Synthetic ATF vs Lifeguard.
Original pan did indeed have a drain plug... dumped the old fluid and removed/installed the pan while it was cold and on the ground.
The Lifeguard smelled fine, though it was a bit of a...

• Gondul
• Replies: 33
• Forum: 6.4 Hemi V8

• 

 

[Lrob4]

Fluid level?

Haven’t checked yet, there’s no dipstick correct?

 

[Lrob4]

ZF recommends filter/fluid change ever 80-120K kilometers (50-75K -ish miles)
I'd start by getting that done first... I just did mine.
As I'm out of warranty, I'm just going with AMSoil Signature Series Fuel-Efficient Synthetic ATF.

No need to level the transmission case per the email I received from ZF... just make sure the truck is level.
The green sheet lays out the steps a bit easier and there's plenty of time to top off the fluid before it hits temp... just try to do the change on a cooler day.

Thread 'ZF Fluid change on 2019 2500 6.4'

Oct 30, 2025

Changed the transmission fluid @ 72K miles.
Minimal towing of the TT so I was ok with waiting this long.

Picked up a MOPAR filter as it came with new hardware (also had 4 magnets) and I couldn't really find a solid/consistent review on the Dorman (which apparently can have only 2 magents), wasn't interested in a metal/bigger pan.
Used AMSoil Signature Series Fuel-Efficient Synthetic ATF vs Lifeguard.
Original pan did indeed have a drain plug... dumped the old fluid and removed/installed the pan while it was cold and on the ground.
The Lifeguard smelled fine, though it was a bit of a...

• Gondul
• Replies: 33
• Forum: 6.4 Hemi V8

• 

Yeah that’s what I was gonna go with… or lifeguard 8, not sure yet. A buddy of mine who’s a dodge tech suggested a relearn as well.

 

[Gondul]

Yeah that’s what I was gonna go with… or lifeguard 8, not sure yet. A buddy of mine who’s a dodge tech suggested a relearn as well.

Not sure what a relearn will get you... you're overdue for a fluid replacement.
IMO, I'd do that first... best of luck.