I just noticed this the last couple of days. I have 18,000 miles on my 5.4 2WD Screw. I did a full throttle run from a standing start (entering a highway with no ramp). The first to second shift had a slight pause and then a hard thunk. I didn't watch the tach, but there was plenty of torque being transmiitted with the thunk (a real kick in the butt).
I wonder if the transmission is letting the engine "wind up" between shifts a little too much. I wouldn't want to break anything. I also had my windows closed and the A/C on, so I didn't notice if I "chirped" the tires in second gear.

 

hehe, doubt you chirped but, it sounds like you're just like the rest of us on the infamous....

1------2------shift


It's never been a smooth shift and is definately on the top of the list of several folks.

RP

 

I actually had that happen on a mountain incline also... shifting from 3rd to OD.... long pause going uphill....

 

Mine sure doesn't shift hard. Even at WOT, the 1-2 shift feels like a wet noodle stretching out and seems like it takes about 3 seconds to happen. I really need a chip!

 

Go over to the Transmission Forum and look at the transmission posts about sloppy shifting. Seems to be a topic that has been mulled over greatly. I've got 40,000 on a 2000 F150 ext cab 4X4 with the 5.4
Had some sloppy, hanging shifting problems and a guy suggested that Seafoam Trans Med. Put in a bottle yesterday morning and ran down to Tucson and back (about 300 miles) and it seems to have cleaned up the tranny and the shifting.....SO FAR, as I drove it around after I got back, knowing it was plenty hot. This was after having the tranny flushed last weekend......so I know things are clean. Good Luck.......

 

SuperChip and shift kit good solid shifts
normal driving and chirp the tires shifts
at wot.

 

My truck didn't shift hard, but it didn't go when you stomped on it or towed a trailer. It would only go 30mph from a dead stop when you floored it. If I gave it a lot of time, it would get up there in mph.
The dealer hooked it up to the computer and said it was staying in 2nd gear because the computer codes had somehow been erased. They reprogramed the computer and now its like driving a different vehicle. It never made the thunk people are talking about, except while towing.

 

Ever since I put my chip in, it has made a huge diffrence. I always have a nice firm shift in all gears.

I don't know how much more firmness a shift kit adds, but what I would worry about it damaging the transmission by having it shift too fast and hard?

Again maybe a shift kit is totally cool, and won't cause any additional wear on the transmission but I don't know how true that is.