Originally Posted by RockyClymer
Could it be a loose band in OD? An adjustment or visit to an auto tranny shop might help diagnosis....
No bands in the 42RLE.
Originally Posted by JIMBOX
Do you have larger tires and no diff. regearing ??
Could possibly be engine load at 1800/1900 rpm and the MIGHTY 3.8l engine is "straining"-vibration-long before downshift
This is a very good possibility. It's the main reason I keep the O/D off if I'm not on the highway, even if I'm at a speed limit of 55 mph with lots of long hills.
On the highway at 65+ mph, with O/D on, I will turn O/D off at the beginning of a hill because I know the computer waits too long to come out of O/D. This delay will lug the engine, then it's too late. The transmission will have to drop 2 gears in an effort to maintain speed on the hill. Taking it out of O/D at the beginning of the hill puts the transmission in 3rd gear, which gives the engine plenty of rpm to get to the top.
Another possibility is the torque converter clutch. There were issues with it a few years ago. It had to do with it not fully locking. Partial lock is achieved by modulating the pressure to the clutch. Sometimes it modulates at inappropriate times, creating a vibration. There was a flash for it, and if that didn't fix it, it required torque converter replacement.