Pulsating transmission

[Easye124]

Hello, i have a 2019 classic 1500 3.6L that has a pulsation between 0-2 mph. A slow roll like in traffic almost will spill your drink. The weird thing is that if I bring the rpm up to say 1k, it doesn't do it. I swapped the transmission out to another unit from a wrecking yard with similar (70k) mileage and it's doing the same exact thing. it feels the same as warped brake rotors do, and it stops as soon as I put it in neutral. Thoughts?

 

[Easye124]

Side note: no check engine light or codes. I have brought it to two independent transmission shops AND a local Chrysler dealer, they all shrugged and said we don't know.

 

[banditsc]

Sounds more like a rotating part, like the torque converter or flex plate if neutral stops it.

 

[Easye124]

That's what i was thinking when i replaced the tranny. is it typical for an accident to damage the torque converter? is there a procedure to check the tc?

 

[Rick3478]

What do you mean by pulsating? Engine speed changing? Truck speed changing? Frame/body/acoustic vibration?

 

[banditsc]

If it was in a hard enough accident you could have broken a balance weight off the torque converter or flex plate, or cracked the flex plate. Also check for any issue with the engine and tranny mounts since it was in a crash.

 

[Easye124]

What do you mean by pulsating? Engine speed changing? Truck speed changing? Frame/body/acoustic vibration?

Engine speed stays the same, the truck moves back and forth like it has a big cam in it. If I give it a little gas, it doesn't do it, like going uphill. Like maybe I have to build up line pressure?

 

[Rick3478]

I'm not sure what speed the lockup clutch kicks in. Maybe it can't make up its mind?

 

[Easye124]

If it was in a hard enough accident you could have broken a balance weight off the torque converter or flex plate, or cracked the flex plate. Also check for any issue with the engine and tranny mounts since it was in a crash.

it wasn't bad enough to pop the airbags, was enough to replace the radiator, cooler, etc. though. Question though, wouldn't i feel a vibration above 2mph if the weight came loose? It stops at 2-3 mph. weird.