cromulius

There is a grail truck close by for cheap and was wondering about just removing the front shaft and t case on it to gain mpgs. Im spoiled with the great mpgs on my truck and dont need the 4x4 to get the boat out of the water. How much drag would remain on the front axle and cost mpgs? I assume you would have to change the trans or tail. Any thoughts? I would love the extra couple of inches on the 4x4 truck for jobsites with heavy loads on the truck.

Purplezr2

I doubt you would gain much, the only rotation mass that is added are the driveshaft inside the tubes. I would just run in 2 all the time and not worry about it.

Dr. Evil

I cant imagine why you would want to do this

cromulius

Thanks for that great input Dr Evil.

Dr. Evil

Lets be a big boy here - if you ask for peoples thoughts you are going to get them. Grow up.

cromulius

I'm hitting over 23 mpg around town mixed driving now in my 4x2. I'm wondering why 4x4's get such worse mpg.
1. Front drive shaft?
2. Transfer case?
3. Front axle drag?
I have mainly owned 4x4's non 12 valve in the past and rarely used the front wheels. In the southern states there is not much need except a muddy deer lease once in a while or job site. The added fuel cost is much better invested in the market if you ask me. I'm debating the grail truck for the rear doors and the nice price.

cromulius

Constructive comments only. Dr. Evil please move on to another thread.

Tate

The t-case does not turn outside of the input/output shaft. Chain does not spin, front output does not spin. So other than the minor frictional losses, thats not costing you. Front driveshaft does not spin outside of 4wd engagement. None of the gears in the diff (excluding the spiders) spin in 2wd. So those are not costing you. Your axle shafts are turning full time. Amount of energy wasted to turn those would be negligible. I converted to manual hubs, never saw a mileage change. The big reason for the lower MPG of 4wd trucks would be aerodynamics and tire size. Put smaller, narrower tires on, and lower it. That will help you pick up some mileage.

infidel

Only reason a 4wd would get poorer mileage is the added weight of the t-case, differential and other components.
Negligible and not even worth thinking about but if you want to balance it out never fill up over half a tank to reduce the weight.

9812vram

Ya, what Tate and Infidel said.

Added weight of the 4X components but mainly it's the height. 4X4 is almost always taller which increases drag like crazy. The less air you have blowing underneath the vehicle grabbing on all the parts hanging down the better mileage you'll get. My mileage dropped just from adding 2.5" leveling blocks to the front Coils.
Removing the front drive shaft will gain 0 in terms of mpg.

Recipe for fuel mileage:
Lowering Kit
Small Narrow Tires
Tall Gears
Good Proper Pump Tuning
Add Egg Between Foot and Go Pedal

cromulius

Very informative thanks y'all.