I have a 2001 F-150 Super Crew 5.4L 4x4, at times when I am towing my boat or camper and the transmission downshifts while going up a hill when I reach the crest of the hill and it shifts back into OD I get a vibration. The vibration is similar to the one you would feel when you run over the little rumble strips on side of interstate. If anyone has had this problem and can help me pinpoint it I would greatly appreciate. This only happen while I am towing, when I am not towing I have never had this happen. Thanks

 

From your discription it sounds like the Over Drive Band is slipping/chattering or it's accumulator is not holding the band tight to it's drum.
What fluid maintainance has been done.
Check the fluid level and for smell or being burnt.
When the trans is out of OD, it's not in lockup. This generates a lot more fluid heat that may be a factor.
If yes, you need transmission service yet to be determined by a good shop.
Good luck.

 

I would suggest not towing in OD. There are cases that its okay, but generally its best not to.

 

Fluid level is full, the fluid and filter were changed 45,000 miles ago, and fluid has no burnt smell. I have been towing my boat (2500 lbs) for 3 yrs and I just purchased my camper(4000 lbs) two months ago. I started feeling this vibration about 1 month ago. Also my truck is equiped with factory tow package which includes trans cooler. Thanks for your help.

 

which fluid did you use? The feeling you describe was exactly what I was getting in my old '95 F150 w/ a 4r70w. I kept describing it as rolling over rumble strips for a second or two. Mine wasn't related to towing though. It was just intermittent. I got all kinds of theories. Then someone mentioned completely draining trans and TC fluid and replacing w/Mercon V. I did this and all was cured.

 

Now that I think about it, while I had the pan down I followed a recommendation to replace a piston w/a redesigned one. Not sure what that piston was called, but I could probably find the thread where it was recommended if you're interested. Not sure if it was the fluid change or the new style piston that cured the rumble.

 

The fluid and filter change was actually done by a Ford dealership, I had the truck in for a recall and they offered to do it for about $30.00 more than the filter and fluid was gonna cost me, so I figured it wasnt worth my time to do it myself. It only happens to me while I am towing and it is also random, not happening everytime it shifts into OD. I would be interested in reading the thread if its not too much trouble. Any help is appreciated, thanks.

 

I can't seem to find that thread. It was about 4 years ago when I did this. But I believe it was called the "bypass clutch control valve". I'll keep checking, and if I find it I'll get back to you. I'm pretty sure it was in the 1987-1996 folder.

 

Found the Ford part # F7AZ-7F251-AA