i have 3.55's in it but I dont have a tach so I dont know rpm's, he|| I would like to know too what rpms I am running at 70 with the 3.55's

 

how much did your gas mileage increase around town?

 

hey guys, I've been reading this post, and it seems everyone is happy with this mod, and forgive my ignorance, but can you tell me what the actual improvements are? I would assume the improvement would be one or two things, or both. Better fuel economy, or better performance, or a cobination of both. I'm mainly looking for better fuel economy, and I have basically a stock 2007 Screw. I am planning on getting an Xcal2 and CAI, but also wanted to look at other mods that would help with fuel economy.

 

the gears will help alot with low end torq and getting started off the line, the truck will be more responsive and some better towing aswell. As for gas milage it probably wont help much depending on what gears you have now. You will be running at a higher rpm on the freeway with the gears.

 

thanks for the info. This sounds like a good mod, but I don't know if it would be a great benefit for me. I don't want to sacrifice fuel economy to go faster. Sometimes I miss my old dodge dakota (withV8), but this truck more than makes up for it with comfort and style.

 

i have 3.73s and say im pretty heavy on the throttle to get going faster on the line. if i got 4.10s would that lower my RPMs from the get-go around town?? and would that result in better gas mileage around town??
i dont know much about regearing please help me out
thanks

 

A. Lower gears will raise your RPM, relative to how large of a gearing change you make.

B. With same-size tires and a reasonable ratio, MPG may decrease slightly, or remain about the same...while providing more perfromance due to torque multiplication. A large jump may cause a more-noticeable MPG drop of a few percent (or more), as well as greater torque multiplication.

C. If you have super-large tires (35-inches or larger) and stock gearing, re-gearing to a shorter ratio often increases MPG by a few percent (or more) & will restore a lot of your lost power.

D. Typically, a two-step drop in ratio will provide about the same MPG, and significant performance increases, on stock-sized tires. Anything more than a two-step drop will likley cause a drop in MPG...unless you are running larger tires, in which case you may want to consider more than a two-step ratio drop in ratio (see C, above)

If you are just looking for MPG, aren't looking for performance, and are running stock tires, then re-gearing may not be for you.

 

ok thanks alot man. perfect answer

 

Keep in mind that a one-step change in ratio (from 3.55 to 3.73) isn't usually worth the expense, as the change is minimal.

Here's are typical Ford ratios for these trucks, to give you all an idea of the steps I'm talking about,

3.31
3.55
3.73
4.10
4.56
4.88
5.13

 

I plan to get some 20's on my truck, would 4.10s bring me back close to stock or would 3.73 better suite my needs (keep in mind I always have about 100-200 pounds of shyst in my bed).

 

What size tires on those 20s?

 

I put 275/55/20 (31.9") tires and wheels on my truck, and compared to stock the truck is just gutless. I have an '06 with a 4.2, 3.55 gears and a 5 speed manual. I used to be able to chirp the tires into second without trying, and now I can barely chirp the tires in first when trying. My mpg dropped around town but I guess it might have helped on the flat highway, but I don't drive on the highway, and I mostly drive on rural 55mph roads or 45mph city streets. Im going with a 4.10 to get back my power and city mpg, and the only time Im on the freeway is when Im going up the mountains .

The best gear ratio depends on how you drive, where you drive, what you want, and tire size.

 

'06STX,
I don't think you're going to notice a difference in highway MPG.

I didn't - went from 3.31 to 4.10, on 285/60-18 tires (about the same diameter as yours).

Most other folks don't report any change in MPG, either, when they go to 4.10s on stock-ish sized tires.

 

Not sure yet what size tire im going with, I know I dont want a real low profile tire cause they ride like butt. not sure how big I can fit in there without rubbing. I lowered the rear via shackles 2 inches to make it level.

 

Did you have an improvement in the city. I find myself having to rev the motor up higher to accelerate as fast as the other cars in the city. My v6 makes its power higher and it's to high geared to pull hard enough down low. I figured it would really improve my city driving.