Was digging through these forums and found:
"The AOD incorporates a somewhat rudimentary overdrive design featuring two input shafts. The inner shaft, which is driven directly from the front cover of the torque converter bolted to the flywheel, provides direct drive in Third gear and bypasses the hydraulically driven components of the torque converter entirely; the hollow outer shaft is driven hydraulically by the converter and drives First, Second, and Reverse gears. This is commonly referred to as a split torque path, and it allows 40 percent of the engine's torque to be transmitted via fluid coupling (through the torque converter) and 60 percent to be transmitted mechanically while the transmission is in Third gear. In Fourth gear, 100 percent of the torque is transmitted mechanically - similar to the direct-drive of a manual trans."
Does this mean the AOD inner shaft fits into a splined hub that's welded to the TC front cover? So there's no TC friction disc or some kind of "damper" (i've heard referenced) that achieves the direct drive???
So therefore friction additive "shudder stop" would do nothing to the torque converter?
And the 60% in 3rd is controlled by AOD, and also the 100% in 4th gear is the TC through the inner shaft directly to the planetary?
I've got a bad shudder when in 3rd or 4th at lower rpms.

Thx for any insight.

 

You essentially have everything correct.

3rd and 4th are mechanically locked to the engine by the inner shaft. The inner shaft splines into the front of the torque converter as you said above. There is no torque converter slip in 3rd or 4th. The torque path is split in 3rd, but it is mechanically locked to the flex plate through the inner shaft.

if you have a shudder in 3rd or 4th, it is not caused by slipping clutches in the torque converter.

With the mechanical link between the engine and transmission having no buffer, it is very likely that an engine misfire will be perceived as a transmission shudder by the driver.

it is also possible that a misadjusted TV cable could cause the transmission to shudder by not applying enough pressure to the clutches. It’s also possible that this can no longer be fixed without a rebuild if it is a symptom of a long term problem of TV cable being out of adjustment.

As a test, id consider adjusting the TV cable such that it bottoms out at WOT. This will apply more pressure to the clutches at all throttle positions. It will also result in much later and noticeably harsher up shifts and earlier and harsher downshifts, which you may or may not like.

 

Thank you for the detailed answer!