13FX150

Ok so i have a 2006 F150 Screw with a 7" FabTec lift on 35's. I have already added a posi rear with 4.56 gears and 4.56 gears in front. i have good power with a procomp programmer but it seams if i had more than an 3 speed W/overdrive i could do better on fuel on the highway. Has any one on here ever upgraded there tranny to say a 6 speed auto like the newer trucks run? Would this help offset my gearing at higher speeds? Mine does great on fuel intown and off road but sucks fuel when i an running 75-80 which most highways here in Texas are 70-75 posted..

techrep

iTrader: (1)

Did not know Fabtech made a 7" lift

13FX150

its a 6" with adjustable coil overs adjusted up to a total of 7" over factory height and add the tires and i am sitting 8.5" over stock.

bourgeois1269

Nice truck 13FX150 !!!

techrep

iTrader: (1)

so it’s not a 7” Fab Tech lift ?

redknight1

ok, so here are the reasons why a trans swap from a newer f150 will not work. Especially if you wanna go from a 4 to 6 speed.
1. mounting most likely not the same and will require welding and fabbing.
2. No idea if the bolt holes will line up. I know on chevy cobalts that the ss transmission was entirely different than the base model manuals and couldn't be swapped cause the bolt pattern inside on the fly wheel were different
3. The wiring, dear god the freaking wiring will be beyond insane. You'll need an expert programmer who can recode your current engine to tell it that it has an entirely different transmission, redline, gearing, shifts, shift firmness, all of that is gonna be different. Who knows if any of the wiring you have going to it will now will even just plug in. In that case, you'll have a lot of soldering and repinning wires to do. You'll need some in depth manuals for sure.
4. Size, if the trans isn't exactly the same size you'll need to modify the front axles, driveshaft, etc. Who knows where the new trans shifter will want to come through on your truck. If it's off by even a few inches...yeah.

Mod (Ret.)

And you have now discovered why you can't have both great highway mileage and the gearing you have installed to assist with the 35's.


My son complains all the time that his mileage sucks at highway speeds. As I stand next to his truck (also equipped with 35's) along with his high gearing that he "just had to have" to pull his truck at lower speeds through the trails, I simply shake my head in total puzzlement and wonder why he too can't have both?

13FX150

Well it was a nice dream to put a 6 speed in as that would have salved the problem (i think) but i figured it would not be easy..lol guess you just have to Pay to play!!

13FX150

It is a 6" Fab Tec with upgraded 8" 4.0 Coil overs that can adjust up to 8" mine is set at 7" so no not technically a 7" really a 8" with it set to 7".

chayes627

There was someone on here that had looked into it before. The final gear ratio was almost identical to ours so there would be no change in highway mileage. The new 6 speeds have a computer that is dedicated to transmission only.