Shuddering ruff vibration between 40-50mph at 1500 rpm and under. What is it?

[2007HummerH2]

sounds like the torque convertor is slipping/searching when it goes into overdrive at 40mph. These transmissions are notorious for doing that. Watch the rpm gauge and if it jumps 100-300 rpms while shuddering, then it probably is the torque convertor.

 

[GreyGhost]

Update… the engine light finally came on. I read the code and it's the torque converter selenoid. After the light came on it hasn't shuddered anymore, but the rpm's stay a lil higher now and it's drinkn more gas. Anyone know if the selenoid can be changed without going to a tranny shop?

 

[Mb30sdl]

HMBP got solenoid code, but it slips when shifts 3/4. we decided to rebuild trany even that it was done a week before I bough it. With almost 260k on it, I desided to do comelette overhaul with all possible upgrades. -unbrekable, just the way I like it

 

[GreyGhost]

I'm not getting any slippage it shifts great. That's why I'm wondering if that selenoid is external so I can change it myself to see if that fixes it?

 

[Mb30sdl]

I think it's in valve body assy., you have to drop pan to remove it. You may double check that.