2021 3500 HO DRW transmission grinding from 3rd to 2nd

[wartowne]

i just turned 20k miles and about 5k miles ago, I started noticing that the aisin trans will make a grinding sound when coming to a stop. At times it’s so bad that you would think the truck is about to stall out. Tow/ haul modes guarantees it will do it every time. Normal drive mode is only occasionally. Tow haul plus the exhaust brake and you would think the tranny is fixing to drop onto the road. It does it loaded up with 2k pounds in the bed or empty. Load does not matter. Acceleration shifting is tight and fantastic. This anomaly ONLY happens when coming to a stop.
Anybody?

 

[elephantrider]

what did the dealer say?

 

[wartowne]

Dealer first blew me off and said they “couldn’t replicate customer concern“ which was funny since it did it on the way out of their parking lot. I have an appointment on Feb 28 for the shop foreman to ride along. I’ll make sure he gets his money’s worth. Lol

 

[dslbrnr]

Following

 

[wartowne]

Dropped it off at Huffines in Lewisville, TX after a ride along with the Transmission guy. We weee able to replicate the issue no problem. He thinks it may be a resonance in the drive line somewhere. We shall see… fingers crossed. I do love this truck!

 

[wartowne]

The transmission tech at Huffines found a loose bolt in my passenger side Carli lower control arm drop bracket. Not sure how that would have come loose since those bolts are torqued to 200 ft/lbs. I will have to keep an eye on those going forward. It still is making the sound but at this point we are all pretty confident it’s not the transmission and is more likely a resonance between 3rd and 2nd in the drive train. I wish we could have hooked up a computer to watch the hydraulic pressure while shifting and diagnosing the issue, but that didn’t happen. It feels like they may have reset my transmission as the shift pattern was different driving home. Bottom line I’m going to keep running it and monitor the situation. I feel confident one way or the other that if something happens they will square it away. Let the truck “excess weight reduction” commence!

 

[Bigwalnuthoney]

'21 3500 HO- I get what might be a similar noise. I notice it most when I've been slowing with exhaust brake engaged then lightly get back on the throttle. It reminds me of a lugging powerstroke. Haven't had it to the dealer.

 

[wartowne]

'21 3500 HO- I get what might be a similar noise. I notice it most when I've been slowing with exhaust brake engaged then lightly get back on the throttle. It reminds me of a lugging powerstroke. Haven't had it to the dealer.

I will say that after a strategic “excess weight removal” last night and driving 200 miles today trying to get the truck to do it, it did NOT! I’m so happy
It must be some kind of resonance in the HO exhaust system. I kinda had a feeling that’s what it was after the ride along with the dealership.

 

[dslbrnr]

I had a heat shield around the DPF exhaust that was contacting the cab. It was real thin metal and just bent it down slightly. I also tapped around underneath with my fist and found the def tank cover had a rattle. I removed the two bolts holding the cover and applied a couple pieces of thin weather strip between which stopped the vibration/rattle.
The other day I closed my rear door and heard another rattle underneath which turned out to be the shield around the fuel tank. Applied another small piece of weather strip which stopped that rattle