Hi all,

I have a 2001 F-150 RC/SB 4wd with 5.4 that I've been towing our travel trailer with. I am running an SCT tuner with a custom VMP 93 octane towing tune. I had to back off the timing a smidge due to light pinging under heavy load, but otherwise it has been doing good. I have also set the transmission shift points and pressures that work very well too. My question is, while cruising at highway speed with the travel trailer (about 65-68 mph) I find that the transmission will not downshift as fast as I think it should. For instance, while at highway speed, I approach an incline that causes me to lose speed. I press the gas a little further, at this point it would be nice to have a downshift before losing too much speed, but it won't downshift until I've lost about 10 mph and then when it does downshift, it hits hard. What can I adjust to change the 4-3 downshift point? I'm looking for a sweeter (quicker) down shift point between 4-3, one that isn't as harsh and keeps the engine more into it's powerband. Any advice would be great! Thanks.

 

tow/haul button (overdrive off/on) button on gear selector........and I wouldn't have changed the shift points or pressure in the tune.

 

I always tow with OD off. The transmission shifts great with the exception of the 4-3 downshift. It just waits too long to downshift, IMO.

 

If OD is off, then it never will get into 4th gear........

 

Yep, you're right. I stand corrected. I'm referring to the 3-2 shift.

 

Just grab manual 2nd with the shifter.

 

No, don't do that. No need for manual shifting. I believe you are wanting the JMOD. Jerry Wroblewski designed the 4R70W and released specs on a modified valve body. I did the JMOD, along with other things when I rebuilt my transmission. My transmission shifts incredibly fast now.

Anything you'd ever want to know about the Ford AODE/4R70W/4R75W transmissions can be found here: http://www.tccoa.com/articles/tranny...on/index.shtml

I'm no pro, but I am pretty knowledgeable of the 4R70w. I have rebuilt 2 now. I can try to help with any questions you have.

 

If you go to the link I posted above, chapter 6 explains the mechanical or how/why it works the way it does.
Then go to page 13 to modify it.

If you are going to do the modification, I recommend a few preventative upgrades. Get the new accumulator valve as shown and get the SHIFT SuperTuff separator plate. Follow the guide for opening the holes on the separator plate to allow for higher line pressures and faster accumulator actuation.

 

I almost forgot, The Transmission Bench. This guy is extremely thorough, very articulate. He is an old guy, talks a little slow. Sometimes you'll need some patience to stay with the videos, but he does a great job. His videos are here on his website, and also on youtube.
The Transmission Bench

 

Put the pedal to the floor, and it'll downshift..