Wow!.. a lot of reading here, and a subject which touched a raw nerve (I've been through my own "rebuild hell" this summer with my AOD).
Here's my story:
Transmission lost 3rd/4th gears in March. Not a particular worry for me because it was OEM and my AOD has seen 180,000mi of somewhat hard use
I was looking forward to a performance rebuild when it cacked.
Take it to a local "performance" shop where they promised me the world (upgraded parts, shift kit, etc.,). Get it back and it lasted mere hours before it stopped shifting period. Take it back... they repair it 3 more times. Get it back, same result... stops shifting altogether after a couple of hours. I suddenly realize these guys know dick about what is causing this and I have no hope of them being able to fix it properly. The only good thing to come out of this is I now have newer 4R70W gear set components.
During the first few hours (when it would shift somewhat) the symptoms were the same as many of you describe... late/erratic shifting, bogging the engine when coming to a stop, etc,.
After doing a lot of research and talking with Len from Lentech, we both agreed it was either the governor or valvebody causing the shift problems (the 2 components that control shifting). *NOTE* At this point the assumption is the gear set components were installed correctly.
I then purchased a Lentech "street terminator" valvebody and governor and had them installed by my local dealership (The AOD requires a
different weighted governor when installing the wide-ratio gear set, which the first shop didn't have a clue about... if the OEM one is used, the 1~2 & 2~3 shift RPMs will be too high).
Well damn!.. wouldn't you know it? after a couple of hours the SAME thing happened... the tranny stopped shifting altogether. Talk about frustrated... at this point I've spent $3k and I still don't have a working tranny. Worse yet, I still don't know what's causing the problem!
More research, more consultation with experts, more talk with Len, and slowly the concensus started pointing towards fluid contamination. I pulled a small amount of tranny fluid out and discovered a fine silt in the fluid... confirming the assumption of contamination.
After finally finding someone else to attempt yet another teardown/rebuild (thanks to club member Greg C. for pointing me to John Hart), I now have a working AOD!
The problems...
When the first shop installed the new gear set, they made several mistakes. They installed too many clutch plates in the 3rd gear "direct" clutch pack. They also didn't line up the pump housing correctly (which prevented fluid flow to certain circuits), and they somehow installed the 2" OD band incorrectly, which caused it to be partially engaged all the time. Add to that a ballooned TQ converter from overreving and you end up with a mess!
What was happening is (and I'm going from the explanation given to me) the 3rd gear clutch pack and the OD band were constantly engaged all the time to some degree and this was the source of the fluid contamination (clutch material). The contaminated fluid circulated throughout the tranny and gummed up the valvebody and governor, which quickly resulted in the "no shifting" situation. After 300 kms the 3rd gear direct clutch and OD band were completely worn out!
For all the money and grief I went through, I could have just bought a complete Lentech from the start. Hindsight is easy, I know...
AODs can be built to last if the
right person/shop is doing the work... unfortunately there are too many others who just
think they know what they're doing.
I love the way my AOD performs now, and the wide ratio gearset is a nice improvement, but I still don't like the part-throttle 2~3 shift. It's a little too firm for my taste (mainly due to the fact that 3rd gear is fully locked up in the AODs, and there is no fluid pressure cut-back during the shift like the stock AOD has). Next year I'm going to a non-lockup TQ converter which will soften this shift some.