So this tranny (700r4) just got rebuilt about 3 months ago. 1st thru 3rd is strong and fine...shifts a bit early but it is good. When I get to about 33mph at half throttle or less, the tranny shifts into 4th and then immediatley goes into lock up. Well at that low of speed, the car shakes a bit and def shakes alot more when I push on the gas....has a kind of under powered feeling. The car snaps out of the vibration thing once it gets to about 45mph. My assumption is that the tranny is going into either 4th or lock up too soon. Yes I know about the switch option but I don't want to go that route because the car is not supposed to do that in the first place plus I don't want to modify this car too much....not why I bought it. Any ideas?

 

Old thread, but I'm having roughly the same problem. Anyone care to chime in?