Low speed clunking. Say 20mph stop and go traffic.

[Moledigger2019]

Any one have clunking at low speed acceleration and deceleration. Had my pinion seal replaced a while back. 

[Fowler]

Yes I did I also had a vibration on and off on the highway and turns out there a TBN out on the oil used in the 8 speed tranmission paired with the 5.3 v8 they did a transmission flush yesterday and seems to be ok now 

[Norman Dalisay]

I do! So the tranny flush cleared the noise?

[redwngr]

5.3L 10 speed?

Possibly related? 

 

https://gm-techlink.com/?p=15387

Shudder Condition When Coasting to a Stop

September 30, 2021

Some 2021 Silverado 1500 and Sierra 1500 trucks equipped with the 5.3L V8 (RPO L84) and 10L80 10-speed automatic transmission (RPO MQB), excluding models with RPO YK9, may have a shudder condition when coasting to a stop between 15—13 mph (24—21 km/h). (Fig. 10) The shudder may feel similar to driving over rumble strips on the pavement when the vehicle is coming to a stop.

 

Fig. 10

 

During diagnosis, the shudder condition will be easily duplicated every time the vehicle coasts at the affected speeds. The shudder may be due to the reduction in the number of cylinders firing during deceleration, which may lead to structure-borne noise, vibration and harshness (NVH) on some vehicles when coasting to a stop between 15—13 mph (24—21 km/h).

If the shudder condition at the affected speeds is confirmed, reprogram the Engine Control Module (ECM) with the latest calibration available. Do not replace any parts for this condition.

It will also be necessary to perform the Crankshaft Position Variation Learn procedure covered in the appropriate Service Information once the ECM has been updated. The crankshaft position sensor variation is used to calculate reference period errors caused by slight tolerance variations in the crankshaft and crankshaft positon sensor, which allows the ECM to accurately compensate for reference period variations and detect misfire events over a wider range of engine speed and load. If the Crankshaft Position Variation Learn procedure is not completed, the ECM calibration will not provide the desired results.

TIP: Always verify that the VIN displayed in the left-side drop-down menu in Techline Connect and the top-center window match the VIN plate of the vehicle to be programmed prior to using Service Programming System 2 (SPS2) for programming or reprogramming a module. (Fig. 11)

 

Fig. 11

 

Refer to Bulletin #21-NA-207 for additional information.

 

 

 

[M1ck3y]

Put heavier tires on.

[Phantom 4D]

Just saw this thread. I've had issues with a slight vibration on the highway. I could feel it in the floorboard and steering wheel. Hard downshift from second to first coming to a stop. Some hard up shifts. I have the eight speed. Yesterday, took it in for oil service. Told the service writer what was going on. We took it on the road, and of course it wouldn't duplicate. Pulled in to the service lane and it did do the hard downshift. After explaining how that transmission works, he said it needed a fluid change. 

I asked if that was supposed to have been done on all 2019s prior to sale. He said he would have it done anyway.

After service and on the way home, at 1.5 hour drive, it did seem to eliminate the vibration. But not the hard downshift coming to a stop. Called him when I got home. He again said it was the transmission design that causes the hard shift. Anyone else?