My 2006 TJ with the 4.0 motor, 42rle trans and 3.73 gears was having hard shifts only when I first drove it. Then it would calm down and shift smoothly. I checked and made sure the trans fluid was full, clear and pink with no burn smell. Still did the hard shift in the morning. Then I found how many others with 2005-2006s withthe (I don't like it ) 42rle had the same issue. Finally on Saturday morning I disconnected the battery negative terminal and let it sit that way for about 1 and 1/2 hour. Hooked it up and he problem was gone. Shifted perfectly smooth, no hard shift at all. So it's been only two days, but still working like it should. So many other were correct, it isn't the trans, it's the stupid computer control things telling the Trans to stay in gear too long and then shift hard. I read that some others did the same thing I did and it lasted them about a week before theirs went back to hard shifts again. I can't afford to go hunting for a different PCM, nor would I know what I was doing. I'll see by the end of this week if it still works good or goes back to the nasty shifting. Strange I've had this Jeep for about two year now and it never had this problem until I switched from 15" rim withabout 29 or 30" tires to the Rubicon factory 16" wheels with 31" tires and got in the habit of turning off the Overdrive before I took off. Anyone think there may be a connection there? Maybe I spazzed out the computer? I would love to know what others think and did.