Gearing and MPG on AWD

[kblackav8or]

My 2000 Mounty has 3.73's in it. 5.0 and AWD. I have read lots of threads on bad MPG and ours is a pretty steady 14 in the city. What I wonder is if anyone has switched to 3.55's. Can you? What about disabling the AWD for the summertime. Can this be done? What about part time conversions? Even if you did something like add locking hubs it might tend to save a little on MPG. I am not as familiar with the transfer case and front drive on this truck as I would like to be. I ordered my PSD with manual tranny, transfer and hubs so I would be in control. No such options with the Mounty.
So the question is gearing and AWD issues and affects on MPG?
Kevin

 

[aldive]

Its a common misconception that going to higher ( lower number ) gear ratio will result in increased gas mileage. For maximum mileage, the motor needs to run in the most efficient rpm range. I also have the 3.73 gears and get over 30 MPG ( highway ).

 

[kblackav8or]

It isn't a misconception at all. It may not be true all the time but most of the time it certainly has an impact. My PSD gets 2-3 MPG better running 3.73's then it did when I had 4.10's. Granted not an Explorer but it is an example. Tire height also plays into this as well. I am interested if there is a more optimum ratio for MPG then I currently have. It would seem to me 3.55's for a mostly street driven vehicle are certainly worthy of a discussion. It is all a compromise.

 

[Robb]

What I wonder is if anyone has switched to 3.55's. Can you?

Yes, it can be done, but I don't believe anyone has actually done it for two reasons 1) you aren't going to see much change at all going from 3.73 to 3.55 and 2) at somewhere around $1000 for regearing both ends, it isn't a cheap proposition.

What about disabling the AWD for the summertime. Can this be done? What about part time conversions?

The only way you can make your AWD tcase not drive both ends, is to physically remove the front shaft.

Even if you did something like add locking hubs it might tend to save a little on MPG.

There is no such way of installing lockouts on the front of a '95+ Explorers. They are live axles.

 

[kblackav8or]

I am thinking maybe a carefull selection of taller tires and possibly a wheel change might have the desired affect. A few hundred rpm can make a noticable difference. Pretty sad that my 7800 lb dually diesel pickup gets better MPG in all but pure highway driving. The mounty then matches the big truck but only barely. Anyone tweeced their 5.0's with a tweecer? I think the smog calibration has alot to do with the crumby milage. When a 12 yo 351 powered F-150 supercab (my dad's) gets better gas milage (4x4 auto as well) all around there is more to it. Calibration has to be playing into this as well.