My truck is an 2006 XLT SCAB 2wd with the 5.4L. It currently has a limited slip rear end spinning 3.55:1 gears on stock wheels and tires. (255 65R17) I am considering moving to 4.10:1 gears. While the loss in fuel millage will not be a show stopper, I would like to know how much of a hit I can expect to take at the pump. My motor is stock and the only engine mods I am ever going to do are a 3" cat back for sure, and maybe have it chipped and tuned when the warranty runs out. Any info will be appreciated.

If this is a double post I apologize. I am having some funny issues with my computer this evening.

 

I'm ordering 4.10 Motive Gears when the sun rises (tomorrow). I can't wait... 3.55's stink... but not as much as 3.08's or 3.31's... lol

How much of a gas difference... I dunno. I've got the 4.2l V6 with a 5 spd. But I've been keeping track of my gas mileage with my 3.55's... so I will find out.

Why am I doing this? Not really for performance... but rather 4 good reasons:

1. When working around the yard, I like dropping the truck in 1st and driving slowly without giving it gas and 4.10's will allow me to do with well.
2. Towing. I tow lots of stuff... yah, kick me, I didn't get a v8... but Ford didn't offer a stick in a v8.
3. Less wear and tear on the friction material on the clutch and flywheel.
4. Better city driving... less down gearing. Stay in 4th and forget about it unless stopping for a light... but even then, it makes skipping gears a lot easier. (might save some gas.)

 

it sounds like you have a plan. let me know what your mileage difference is.
thanks
Ron

 

My 5.4 regular cab GAINED mpg when i did 3.55's to 4.11's. Yes the odometer was recalibrated.

One of the best mods you can do IMO.

 

My MPG was unchanged, went from 3.31 to 4.10.

Towing MPG improved a bit.

All-around performance improved noticeably.