Wah! Off the line shudder with new trans

[davepl]

Well, the 4L80E is in and everything is jiggy... almost.

When you take off from a stop, if you use about 1/4 throttle at least, once you roll out maybe a truck length a "shudder" develops that lasts through about half of first gear.

The only way I can get it to "sustain" that effect is up a hill. Like up a 15% grade or so it'll shudder the whole way if you find that combination of load and speed.

It's like the driveshaft is winding up and releasing almost, or (more likely but I hope not) something amiss in the transmission itself.

The posi is very tight, and around corners you can feel it, but this is in a straight line.

On the highway, around town, no other symptoms of it. Fine at speed, no vibrations or noise of any kind.

I -think- I tried a second gear start (the TCU allows for that) and that it was still there, but I don't remember for certain at the moment, will re-check that on Monday.

Anyone know enough about transmissions to make a guess? I'd like to have a few theories for the tech to chase on Monday. He did the install and now he's going to chase this issue...