Well, I have a 2000 F250 ext short V10 lifted 6.5 in on 36's and the gas mileage sucks.. To make it worse I'm adding 5" hangars and putting on 39's. Has anyone taken their front drive shaft off to try and increase gas mileage. I've heard of people doing it, and I rarely off-road. If so, how hard is it to take off and put back on in case I wanted to go offroad for a weekend?.?

BTW, new to the board, been lurkin a little... Other mods include a Flowmaster 50, superchips reprogrammer, K&N intake, billit front grill, exchanged the smaller mirrors for the Telescoping one's, pioneer 6500 deck, exhanged all the stock speakers for pioneer, Pro-Box sub w/2 JL 10w0's running off a Rockford Punch 900 mono 2ohm stable, Limo tent all around, and westin step bars.

 

Welcome to the V10 obsession

Gas milage sucks because of the aero effects of these trucks sucks. Lifting them makes it worse. The 4x4 front axel is not a drag in 2wheel mode unless your hubs are engaged. The only drag the 4x4 system causes in 2 wheel mode is dur to the weight of the entire front end. No need to drop the front drive shaft as yu will not gain one bit of extra MPG.

Your tire diameter increases need to be compensated with appropriate reductions in gear ratios so you are right at 1900-2100 rpm in OD for the best fuel milage. Your 39"s would probably need a set of 4.88:1 gears to get near this figure.

 

I'm in the same boat as you, have about the same setup running 3.73 gears (I know, I know, need to change 'em out). I have a 38gal. tank and only get about 300 miles out of tank.

I didn't buy the truck for the gas mileage though, I knew it would be crappy from the start (stock).

 

Yeah, same here, it was always the truck I wanted, and I never complain about the gas mileage to other people, only to people that have the same truck! I'm just trying to conserve as much as I can, and seeing as I have the smaller gas tank, about 25 gallons I think..

 

A little perspective so you can stop worring about the MPG and get back to modding and enjoying your SuperV10Duty!

10,000 miles / 9.0mpg X $1.83 is $2033
10,000 miles / 11.0mpg X $1.83 is $1663
10,000 miles / 14.2mpg X $1.83 is $1288

so even if you got all the way up to max reported MPG you would only save $745 per 10,000 miles. Heck you got that much tired up in the 6.5 lift! and the 39s are going to be pricey too!

If you have 3.73s you will not like the preformance of the 39s and I assure you the cost of 4.88:1 in BOTH differentials will cost some serious pesos!

 

If you go under you can spin the front drive shaft by hand so it is not hooked to anything when in 2 wheel drive so removing it would do nothing.

 

Maybe this is a dumb question, but from me, it wouldn't be the first time. Are you calculating the mileage based on the odometer reading divided by the number of gallons at fill up? Have you had your speedo recalibrated since adding the tall tires? If not, remember you've actually travelled more miles on that tank of gas than your odometer is displaying. For example, let's say you had 33's on before, and you were getting 250 miles on your 25-gallon tank, for 10mpg. They are going to rotate 611.17 times per mile ((5280 ft/mile * 12 in/ft)/(pi * 33)). Now you throw on the 36's and they only rotate 560.24 times per mile. You drive through a tank of gas and the odometer only shows 229.17 miles. You incorrectly calculate your new mpg as 229.17/25=9.17mpg. Problem here is your tires rotated 560.24 times per mile while your odometer thought they were rotating 611.17 times per mile. You actually travelled 611.17*229.17*113.094(in/rotation)/12(in/ft)*5280(ft/mile)=250 miles. So you travelled 250 miles on the 36's for 10mpg even though the odometer shows you went 229.17 miles on them for 9.17 mpg. In the real world, of course, you would see a dip in mileage due to wind resistance, etc.

 

I guess I really never did the math, but that doesn't seem to bad actually... To bad I drive 30,000/yr...

How much does it cost for the 4.88:1's? And roughly, I know all shops are different, but if any of ya'll have had it done, how much did it run ya?

Yes, I had to buy a speed recalibrator...

 

You really need to find a axel shop in your area NOT Ford dealer as they are NOT experts. Prices on these boards are ALL over the place from a low of around $1400 up to over $5K depending on "extras" like electric or air locking front and rear diffs.

Observation/idea... I love my V10 but realized that daily commuting was going to be very expensive with it. Found a $700 beater VW deise Rabbit that gets 40+mpg and use it for the simple running around and occasional commute but still I mostly take the truck to work cuz you never know when you need stuff at Lowes etc. You would be amazed at how BS trips eat up the milage on a vehicle. I reduced my truck milage over 30% this way. Amazing how a cheap loud stereo and good AC can make the "beater" acceptable for errand chasing.

 

I've thought about doing that, I also have a 2003 Honda CBR600RR that I use about twice a week to go to work.. My stepfather is retired and runs a little garage for old VW's... Maybe I'll just have to buy one off him.. Thats going to put me at waaaay to many toys...

2000 F250,
2003 Malibu Wakesetter
2003 Honda CBR600RR
2005 Honda CR450F

And maybe another beater car.... Thats already waaay too many registration forms I have to do.. If anyone wants to buy the CBR let me know!