Last year I reported symptoms of a shuddering tranny (felt and sounded like I was going off the side of the road where they break up the pavement to waken a tiring driver) but it was happening upon acceleration from a stop. This started 1 week after servicing the transmission (changed fluid and filter) and engine tune-up was done the prior year. It happened intermittently after starting from a stop and just about the time I'm through an intersection. It was happening at either top RMP in first gear or when shifting from 1st to second (somewhere around 28 MPH). My wife reported it mainly acted up when the engine was warm.

It gradually improved over the course of several months and now (about 1 year later) there'* no more noise or symptoms at all. Mileage is now around 115K on an '00 SSEI. I have no idea what the problem was and didn't do anything else to try fixing it. Thought I'd share if anyone else has gone through this dilemma. I like problems that "fix themselves". Now if I can just get the car to fix it'* other problems...like that'* going to happen.

If I can just get that A/C fixed (just reported) I'll be down to just one nagging problem left in the car (my portable indoor pool, for which I'm considering drilling a drain hole).

It'* possible that some of your internal parts were varnished up, and it took a while for the new fluid to remove some of that. It'* just a guess, however. You may want to try something like yearly transmission fluid changes to help extend the life of your transmission. The next change, try a can of SeaFoam'* TransTune just before your change to help clean things out.

Thanks again. I just noticed SeaFoam'* TransTune mentioned earlier this month. So that'* a cleaner (added prior to a flush) rather than a conditioner (added with new fluid)? It was so uncanny that the severe shuddering noise started almost right after changing the tranny fluid/filter (which was done to clear up a thud when initially putting the car into Drive). Dealer mechanics weren't able to troubleshoot either (said I needed a new/reman tranny costing at $1,800-$2,800). I wasn't about to fork over that kind of dough as that'* not far from the car'* value.

Yes, it'* a cleaner. It'* supposed to help get rid of the varnish buildup, amongst other things. I'm not a usual fan of the "mechanic in a can" fix, but this is one that I've had good luck with.