My next mod will be 4.56 gears and a tuner. I expect that to change the feel of the truck (although as mentioned in an earlier post, the truck did not feel that different with the new, taller tires). Before the F150, I had a Tundra SR5 4WD TRD, which had less HP, but much more aggressive throttle tip in and was probably much lighter. That truck was very quick off the line. So much so that it was too prone to spin its tires in low traction situations, like in the snow or off-road. It was pretty tough to keep from spinning the tires on the road. I expect with gears and a tuner the F150 will be more aggressive but not as aggressive as my old Tundra.
You might be surprised. Throttle tip in is awesome now, the back end certainly kicks loose very easily. The first time I take it somewhere new for a service, I get comments from the tech that it just wants to jump off the line and they usually bark the 35s accidentally. Remember it's electronic so it depends on the tuning. It could be tuned to go WOT as soon as you touch it if someone wanted to. With my Detroit locker (lots of backlash) I could even deal with mine being a bit less sensitive now.
What does moving up to 4.56's do to the overall mpg and highway feel (rpm at highway speed)?
I've got 35's on my FX4 SCREW (leveled), and it's killed my mileage. I'm getting 12.9 everywhere, and it will not break 13. Of course, I suppose my trip meter may now be somewhat inaccurate like my speedo is now, but doubt it's that big a difference.
What are you getting on a tuned/geared F150 w/ 35's?
I wouldn't mind a little more pep myself. The truck has always seemed too sluggish....
The 4.56 gears helped a lot. When I first picked it up with new gears I almost thought I should have gone with 4.88s. Just because it didn't feel
significantly different driving it around the neighborhood at first. But now I think it's perfect. The trans is not working nearly as hard to get moving from a start. It doesn't have to downshift constantly on hills, holds overdrive much better, etc. It drives a lot nicer and strains a lot less, but it doesn't feel over geared.
As for freeway driving, at 70mph the RPMs are about 225 higher than stock gearing and stock tires. I'm turning just a hair over 2100RPM at 70mph and it's very comfortable to me. I am getting rid of my A.R.E. cap and getting a small slide-in camper, so I also wanted to be geared lower than stock for that reason as well.
My mileage with 3.73 gears and 35s was around 13mpg average. After 4.56 gears, about 13mpg average. On strictly highway/freeway trips it is around 14mpg. So I didn't really gain or lose any mileage, and that was not the goal anyway. I gained performance and drivability.
4.10 gears would be numerically closer to stock, but that doesn't take into account larger heavier tires, more drag, more weight, etc. Mileage with 4.10s may be
slightly better but it would be minimal.
I do have one friend with a nearly identical truck to mine with the same tires and 3.73 gears, and with the way his is tuned, he says he gets 14-15mpg most of the time. I'm sure if I had mine tuned differently and didn't have to deal with the world's worst drivers around here I could easily make those numbers most of the time too.