Shudder at idle speeds and clunk when changing gears

[thefrey]

2013 Denali XL w/ 204k

I have noticed if I’m stopped and let my foot off the brake, there’s a shudder. It’s definitely not brake related. Sometimes if it’s shuddering a decent amount I will notice a fluctuation in RPMs by 100-200. Sometimes my gas pedal seems like an on/off switch at idle too. After that, there’s no shuddering at all in any of the gears and the transmission doesn’t “slip” at all.

I am also getting a clunk when I “unload/reload” the drive train. For instance, if I am cruising and let off the gas and press the gas again, I feel a slight clunk. Definitely not the motor mounts and it will clunk with even the smallest amount of gas. There is sometimes a clunk going drive to reverse or vise versa.

I’m assuming the shudder is torque converter and the clunk is something else. Not sure if they are related. Any thoughts? Thank you for the help.

 

[alvocado]

Is the torque converter original? If so, it’s very likely that’s your shudder issue. 200k is running on borrowed time with the original TC. Mine blew up at 219k.

The clunk you describe sounds like typical slack in the driveshaft which I’ve experienced since new.

 

[thefrey]

Is the torque converter original? If so, it’s very likely that’s your shudder issue. 200k is running on borrowed time with the original TC. Mine blew up at 219k.

The clunk you describe sounds like typical slack in the driveshaft which I’ve experienced since new.

Dunno if it’s original. I would probably assume so since I bought it with 197k on the clock.

Interesting that you’ve experienced the driveline slack since new. Must be a certified GM feature lol

 

[Joseph Garcia]

@NickTransmissions is our resident transmission expert, and he will chime in with his thoughts and perspectives.

The clunk could be coming from anywhere, including the transmission. Another source of clunking are the supports/bushings for the front differential.